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day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core


->interceptorclj/s

(->interceptor & {:as m :keys [id before after]})

A utility function for creating interceptors.

Accepts three optional, named arguments:

  • :id - an id for the interceptor (decorative only)
  • :before - the interceptor's before function
  • :after - the interceptor's after function

Example use:

#!clj
(def my-interceptor
  (->interceptor
   :id     :my-interceptor
   :before (fn [context]
             ... modifies and returns `context`)
   :after  (fn [context]
             ... modifies and returns `context`)))

Notes:

  • :before functions modify and return their context argument. Sometimes they only side effect, in which case, they'll perform the side effect and return context unchanged.
  • :before functions often modify the :coeffects map within context and, if they do, then they should use the utility functions get-coeffect and assoc-coeffect.
  • :after functions modify and return their context argument. Sometimes they only side effect, in which case, they'll perform the side effect and return context unchanged.
  • :after functions often modify the :effects map within context and, if they do, then they should use the utility functions get-effect and assoc-effect
A utility function for creating interceptors.

Accepts three optional, named arguments:

   - `:id` - an id for the interceptor (decorative only)
   - `:before` - the interceptor's before function
   - `:after`  - the interceptor's after function

Example use:

    #!clj
    (def my-interceptor
      (->interceptor
       :id     :my-interceptor
       :before (fn [context]
                 ... modifies and returns `context`)
       :after  (fn [context]
                 ... modifies and returns `context`)))

Notes:

  - `:before` functions modify and return their `context` argument. Sometimes they
    only side effect, in which case, they'll perform the side effect and return
    `context` unchanged.
  - `:before` functions often modify the `:coeffects` map within `context` and,
    if they do, then they should use the utility functions `get-coeffect` and
    `assoc-coeffect`.
  - `:after` functions modify and return their `context` argument. Sometimes they
    only side effect, in which case, they'll perform the side effect and return
    `context` unchanged.
  - `:after` functions often modify the `:effects` map within `context` and,
    if they do, then they should use the utility functions `get-effect`
    and `assoc-effect`
sourceraw docstring

add-post-event-callbackclj/s

(add-post-event-callback f)
(add-post-event-callback id f)

Registers the given function f to be called after each event is processed.

f will be called with two arguments:

  • event: a vector. The event just processed.
  • queue: a PersistentQueue, possibly empty, of events yet to be processed.

This facility is useful in advanced cases like:

  • you are implementing a complex bootstrap pipeline
  • you want to create your own handling infrastructure, with perhaps multiple handlers for the one event, etc. Hook in here.
  • libraries providing 'isomorphic javascript' rendering on Nodejs or Nashorn.

id is typically a keyword. If it supplied when an f is added, it can be subsequently be used to identify it for removal. See remove-post-event-callback.

Registers the given function `f` to be called after each event is processed.

 `f` will be called with two arguments:

  - `event`: a vector. The event just processed.
  - `queue`: a PersistentQueue, possibly empty, of events yet to be processed.

 This facility is useful in advanced cases like:

   - you are implementing a complex bootstrap pipeline
   - you want to create your own handling infrastructure, with perhaps multiple
     handlers for the one event, etc.  Hook in here.
   - libraries providing 'isomorphic javascript' rendering on  Nodejs or Nashorn.

`id` is typically a keyword. If it supplied when an `f` is added, it can be
subsequently be used to identify it for removal. See `remove-post-event-callback`.
sourceraw docstring

afterclj/s

(after f)

Returns an interceptor which runs the given function f in the :after position, presumably for side effects.

f is called with two arguments: the :effects value for :db (or the :coeffect value of :db if no :db effect is returned) and the event. Its return value is ignored, so f can only side-effect.

An example of use can be seen in the re-frame github repo in /examples/todomvc/events.cljs:

  • f runs schema validation (reporting any errors found).
  • f writes to localstorage.
Returns an interceptor which runs the given function `f` in the `:after`
position, presumably for side effects.

`f` is called with two arguments: the `:effects` value for `:db`
(or the `:coeffect` value of `:db` if no `:db` effect is returned) and the event.
Its return value is ignored, so `f` can only side-effect.

An example of use can be seen in the re-frame github repo in `/examples/todomvc/events.cljs`:

   - `f` runs schema validation (reporting any errors found).
   - `f` writes to localstorage.
sourceraw docstring

assoc-coeffectclj/s

(assoc-coeffect context key value)

A utility function, typically used when writing an interceptor's :before function.

Adds or updates a key/value pair in the :coeffects map within context.

A utility function, typically used when writing an interceptor's `:before` function.

Adds or updates a key/value pair in the `:coeffects` map within `context`. 
sourceraw docstring

assoc-effectclj/s

(assoc-effect context key value)

A utility function, typically used when writing an interceptor's :after function.

Adds or updates a key/value pair in the :effects map within context.

A utility function, typically used when writing an interceptor's `:after` function.

Adds or updates a key/value pair in the `:effects` map within `context`. 
sourceraw docstring

clear-cofxclj/s

(clear-cofx)
(clear-cofx id)

Unregisters coeffect handlers (presumably registered previously via the use of reg-cofx).

When called with no args, it will unregister all currently registered coeffect handlers.

When given one arg, assumed to be the id of a previously registered coeffect handler, it will unregister the associated handler. Will produce a warning to console if it finds no matching registration.

Unregisters coeffect handlers (presumably registered previously via the use of `reg-cofx`).

When called with no args, it will unregister all currently registered coeffect handlers.

When given one arg, assumed to be the `id` of a previously registered
coeffect handler, it will unregister the associated handler. Will produce a warning to
console if it finds no matching registration.
sourceraw docstring

clear-eventclj/s

(clear-event)
(clear-event id)

Unregisters event handlers (presumably registered previously via the use of reg-event-db or reg-event-fx).

When called with no args, it will unregister all currently registered event handlers.

When given one arg, assumed to be the id of a previously registered event handler, it will unregister the associated handler. Will produce a warning to console if it finds no matching registration.

Unregisters event handlers (presumably registered previously via the use of `reg-event-db` or `reg-event-fx`).

When called with no args, it will unregister all currently registered event handlers.

When given one arg, assumed to be the `id` of a previously registered
event handler, it will unregister the associated handler. Will produce a warning to
console if it finds no matching registration.
sourceraw docstring

clear-fxclj/s

(clear-fx)
(clear-fx id)

Unregisters effect handlers (presumably registered previously via the use of reg-fx).

When called with no args, it will unregister all currently registered effect handlers.

When given one arg, assumed to be the id of a previously registered effect handler, it will unregister the associated handler. Will produce a warning to console if it finds no matching registration.

Unregisters effect handlers (presumably registered previously via the use of `reg-fx`).

When called with no args, it will unregister all currently registered effect handlers.

When given one arg, assumed to be the `id` of a previously registered
effect handler, it will unregister the associated handler. Will produce a warning to
console if it finds no matching registration.
sourceraw docstring

clear-global-interceptorclj/s

(clear-global-interceptor)
(clear-global-interceptor id)

Unregisters global interceptors (presumably registered previously via the use of reg-global-interceptor).

When called with no args, it will unregister all currently registered global interceptors.

When given one arg, assumed to be the id of a previously registered global interceptors, it will unregister the associated interceptor. Will produce a warning to console if it finds no matching registration.

Unregisters global interceptors (presumably registered previously via the use of `reg-global-interceptor`).

When called with no args, it will unregister all currently registered global interceptors.

When given one arg, assumed to be the `id` of a previously registered
global interceptors, it will unregister the associated interceptor. Will produce a warning to
console if it finds no matching registration.
sourceraw docstring

clear-subclj/s

(clear-sub)
(clear-sub query-id)

Unregisters subscription handlers (presumably registered previously via the use of reg-sub).

When called with no args, it will unregister all currently registered subscription handlers.

When given one arg, assumed to be the id of a previously registered subscription handler, it will unregister the associated handler. Will produce a warning to console if it finds no matching registration.

NOTE: Depending on the usecase, it may be necessary to call clear-subscription-cache! afterwards

Unregisters subscription handlers (presumably registered previously via the use of `reg-sub`).

When called with no args, it will unregister all currently registered subscription handlers.

When given one arg, assumed to be the `id` of a previously registered
subscription handler, it will unregister the associated handler. Will produce a warning to
console if it finds no matching registration.

NOTE: Depending on the usecase, it may be necessary to call `clear-subscription-cache!` afterwards
sourceraw docstring

clear-subscription-cache!clj/s

(clear-subscription-cache!)

Removes all subscriptions from the cache.

This function can be used at development time or test time. Useful when hot realoding namespaces containing subscription handlers. Also call it after a React/render exception, because React components won't have been cleaned up properly. And this, in turn, means the subscriptions within those components won't have been cleaned up correctly. So this forces the issue.

Removes all subscriptions from the cache.

This function can be used at development time or test time. Useful when hot realoding
namespaces containing subscription handlers. Also call it after a React/render exception,
because React components won't have been cleaned up properly. And this, in turn, means
the subscriptions within those components won't have been cleaned up correctly. So this
forces the issue.
sourceraw docstring

consoleclj/s

(console level & args)

A utility logging function which is used internally within re-frame to produce warnings and other output. It can also be used by libraries which extend re-frame, such as effect handlers.

By default, it will output the given args to js/console at the given log level. However, an application using re-frame can redirect console output via set-loggers!.

level can be one of :log, :error, :warn, :debug, :group or :groupEnd.

Example usage:

#!clj
(console :error "Sure enough it happened:" a-var "and" another)
(console :warn "Possible breach of containment wall at:" dt)
A utility logging function which is used internally within re-frame to produce
warnings and other output. It can also be used by libraries which
extend re-frame, such as effect handlers.

By default, it will output the given `args` to `js/console` at the given log `level`.
However, an application using re-frame can redirect `console` output via `set-loggers!`.

`level` can be one of `:log`, `:error`, `:warn`, `:debug`, `:group` or `:groupEnd`.

Example usage:

    #!clj
    (console :error "Sure enough it happened:" a-var "and" another)
    (console :warn "Possible breach of containment wall at:" dt)
sourceraw docstring

debugclj/s

An interceptor which logs/instruments an event handler's actions to js/console.debug. See examples/todomvc/src/events.cljs for use.

Output includes:

  1. the event vector
  2. a clojure.data/diff of db, before vs after, which shows the changes caused by the event handler. To understand the output, you should understand: <a href="https://clojuredocs.org/clojure.data/diff" target="_blank">https://clojuredocs.org/clojure.data/diff</a>.

You'd typically include this interceptor after (to the right of) any path interceptor.

Warning: calling clojure.data/diff on large, complex data structures can be slow. So, you won't want this interceptor present in production code. So, you should condition it out like this:

#!clj
(day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/reg-event-db
  :evt-id
  [(when ^boolean goog.DEBUG day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/debug)]  ;; <-- conditional
  (fn [db v]
     ...))

To make this code fragment work, you'll also have to set goog.DEBUG to false in your production builds. For an example, look in project.clj of /examples/todomvc.

An interceptor which logs/instruments an event handler's actions to
`js/console.debug`. See examples/todomvc/src/events.cljs for use.

Output includes:

  1. the event vector
  2. a `clojure.data/diff` of db, before vs after, which shows
     the changes caused by the event handler. To understand the output,
     you should understand:
     <a href="https://clojuredocs.org/clojure.data/diff" target="_blank">https://clojuredocs.org/clojure.data/diff</a>.

You'd typically include this interceptor after (to the right of) any
`path` interceptor.

Warning:  calling `clojure.data/diff` on large, complex data structures
can be slow. So, you won't want this interceptor present in production
code. So, you should condition it out like this:

    #!clj
    (day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/reg-event-db
      :evt-id
      [(when ^boolean goog.DEBUG day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/debug)]  ;; <-- conditional
      (fn [db v]
         ...))

To make this code fragment work, you'll also have to set `goog.DEBUG` to
`false` in your production builds. For an example, look in `project.clj` of /examples/todomvc.
sourceraw docstring

dispatchclj/s

(dispatch event)

Queue event for processing (handling).

event is a vector and the first element is typically a keyword which identifies the kind of event.

The event will be added to a FIFO processing queue, so event handling does not happen immediately. It will happen 'very soon' bit not now. And if the queue already contains events, they will be processed first.

Usage:

#!clj
(dispatch [:order "pizza" {:supreme 2 :meatlovers 1 :veg 1}])
Queue `event` for processing (handling).

`event` is a vector and the first element is typically a keyword
which identifies the kind of event.

The event will be added to a FIFO processing queue, so event
handling does not happen immediately. It will happen 'very soon'
bit not now. And if the queue already contains events, they
will be processed first.

Usage:

    #!clj
    (dispatch [:order "pizza" {:supreme 2 :meatlovers 1 :veg 1}])
sourceraw docstring

dispatch-syncclj/s

(dispatch-sync event)

Synchronously (immediately) process event. It does not queue the event for handling later as dispatch does.

event is a vector and the first element is typically a keyword which identifies the kind of event.

It is an error to use dispatch-sync within an event handler because you can't immediately process an new event when one is already part way through being processed.

Generally, avoid using this function, and instead, use dispatch. Only use it in the narrow set of cases where any delay in processing is a problem:

  1. the :on-change handler of a text field where we are expecting fast typing
  2. when initialising your app - see 'main' in examples/todomvc/src/core.cljs
  3. in a unit test where immediate, synchronous processing is useful

Usage:

#!clj
(dispatch-sync [:sing :falsetto "piano accordion"])
Synchronously (immediately) process `event`. It does **not** queue
the event for handling later as `dispatch` does.

`event` is a vector and the first element is typically a keyword
which identifies the kind of event.

It is an error to use `dispatch-sync` within an event handler because
you can't immediately process an new event when one is already
part way through being processed.

Generally, avoid using this function, and instead, use `dispatch`.
Only use it in the narrow set of cases where any delay in
processing is a problem:

  1. the `:on-change` handler of a text field where we are expecting fast typing
  2. when initialising your app - see 'main' in examples/todomvc/src/core.cljs
  3. in a unit test where immediate, synchronous processing is useful

Usage:

    #!clj
    (dispatch-sync [:sing :falsetto "piano accordion"])
sourceraw docstring

enqueueclj/s

(enqueue context interceptors)

A utility function, used when writing an interceptor's :before function.

Adds the given collection of interceptors to those already in context's execution :queue. It returns the updated context.

So, it provides a way for one Interceptor to add more interceptors to the currently executing interceptor chain.

A utility function, used when writing an interceptor's `:before` function.

Adds the given collection of `interceptors` to those already in `context's`
execution `:queue`. It returns the updated `context`.

So, it provides a way for one Interceptor to add more interceptors to the
currently executing interceptor chain.
sourceraw docstring

enrichclj/s

(enrich f)

Returns an Interceptor which will run the given function f in the :after position.

f is called with two arguments: db and v, and is expected to return a modified db.

Unlike the after interceptor which is only about side effects, enrich expects f to process and alter the given db coeffect in some useful way, contributing to the derived data, flowing vibe.

Example Use:

Imagine that todomvc needed to do duplicate detection - if any two todos had the same text, then highlight their background, and report them via a warning at the bottom of the panel.

Almost any user action (edit text, add new todo, remove a todo) requires a complete reassessment of duplication errors and warnings. Eg: that edit just made might have introduced a new duplicate, or removed one. Same with any todo removal. So we need to re-calculate warnings after any CRUD events associated with the todos list.

Unless we are careful, we might end up coding subtly different checks for each kind of CRUD operation. The duplicates check made after 'delete todo' event might be subtly different to that done after an editing operation. Nice and efficient, but fiddly. A bug generator approach.

So, instead, we create an f which recalculates ALL warnings from scratch every time there is ANY change. It will inspect all the todos, and reset ALL FLAGS every time (overwriting what was there previously) and fully recalculate the list of duplicates (displayed at the bottom?).

<a href="https://twitter.com/nathanmarz/status/879722740776939520" target="_blank">https://twitter.com/nathanmarz/status/879722740776939520</a>

By applying f in an :enrich interceptor, after every CRUD event, we keep the handlers simple and yet we ensure this important step (of getting warnings right) is not missed on any change.

We can test f easily - it is a pure function - independently of any CRUD operation.

This brings huge simplicity at the expense of some re-computation each time. This may be a very satisfactory trade-off in many cases.

Returns an Interceptor which will run the given function `f` in the `:after`
position.

`f` is called with two arguments: `db` and `v`, and is expected to
return a modified `db`.

Unlike the `after` interceptor which is only about side effects, `enrich`
expects `f` to process and alter the given `db` coeffect in some useful way,
contributing to the derived data, flowing vibe.

#### Example Use:

Imagine that todomvc needed to do duplicate detection - if any two todos had
the same text, then highlight their background, and report them via a warning
at the bottom of the panel.

Almost any user action (edit text, add new todo, remove a todo) requires a
complete reassessment of duplication errors and warnings. Eg: that edit
just made might have introduced a new duplicate, or removed one. Same with
any todo removal. So we need to re-calculate warnings after any CRUD events
associated with the todos list.

Unless we are careful, we might end up coding subtly different checks
for each kind of CRUD operation.  The duplicates check made after
'delete todo' event might be subtly different to that done after an
editing operation. Nice and efficient, but fiddly. A bug generator
approach.

So, instead, we create an `f` which recalculates ALL warnings from scratch
every time there is ANY change. It will inspect all the todos, and
reset ALL FLAGS every time (overwriting what was there previously)
and fully recalculate the list of duplicates (displayed at the bottom?).

<a href="https://twitter.com/nathanmarz/status/879722740776939520" target="_blank">https://twitter.com/nathanmarz/status/879722740776939520</a>

By applying `f` in an `:enrich` interceptor, after every CRUD event,
we keep the handlers simple and yet we ensure this important step
(of getting warnings right) is not missed on any change.

We can test `f` easily - it is a pure function - independently of
any CRUD operation.

This brings huge simplicity at the expense of some re-computation
each time. This may be a very satisfactory trade-off in many cases.
sourceraw docstring

get-coeffectclj/s

(get-coeffect context)
(get-coeffect context key)
(get-coeffect context key not-found)

A utility function, typically used when writing an interceptor's :before function.

When called with one argument, it returns the :coeffects map from with that context.

When called with two or three arguments, behaves like clojure.core/get and returns the value mapped to key in the :coeffects map within context, not-found or nil if key is not present.

A utility function, typically used when writing an interceptor's `:before` function.

When called with one argument, it returns the `:coeffects` map from with that `context`.

When called with two or three arguments, behaves like `clojure.core/get` and
returns the value mapped to `key` in the `:coeffects` map within `context`, `not-found` or
`nil` if `key` is not present.
sourceraw docstring

get-effectclj/s

(get-effect context)
(get-effect context key)
(get-effect context key not-found)

A utility function, used when writing interceptors, typically within an :after function.

When called with one argument, returns the :effects map from the context.

When called with two or three arguments, behaves like clojure.core/get and returns the value mapped to key in the effects map, not-found or nil if key is not present.

A utility function, used when writing interceptors, typically within an `:after` function.

When called with one argument, returns the `:effects` map from the `context`.

When called with two or three arguments, behaves like `clojure.core/get` and
returns the value mapped to `key` in the effects map, `not-found` or
`nil` if `key` is not present.
sourceraw docstring

inject-cofxclj/s

(inject-cofx id)
(inject-cofx id value)

Given an id, and an optional, arbitrary value, returns an interceptor whose :before adds to the :coeffects (map) by calling a pre-registered 'coeffect handler' identified by the id.

The previous association of a coeffect handler with an id will have happened via a call to day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/reg-cofx - generally on program startup.

Within the created interceptor, this 'looked up' coeffect handler will be called (within the :before) with two arguments:

  • the current value of :coeffects
  • optionally, the originally supplied arbitrary value

This coeffect handler is expected to modify and return its first, coeffects argument.

Example of inject-cofx and reg-cofx working together

First - Early in app startup, you register a coeffect handler for :datetime:

#!clj
(day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/reg-cofx
  :datetime                        ;; usage  (inject-cofx :datetime)
  (fn coeffect-handler
    [coeffect]
    (assoc coeffect :now (js/Date.))))   ;; modify and return first arg

Second - Later, add an interceptor to an -fx event handler, using inject-cofx:

#!clj
(day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/reg-event-fx            ;; when registering an event handler
  :event-id
  [ ... (inject-cofx :datetime) ... ]  ;; <-- create an injecting interceptor
  (fn event-handler
    [coeffect event]
      ;;... in here can access (:now coeffect) to obtain current datetime ...
    )))

Background

coeffects are the input resources required by an event handler to perform its job. The two most obvious ones are db and event. But sometimes an event handler might need other resources.

Perhaps an event handler needs a random number or a GUID or the current datetime. Perhaps it needs access to a DataScript database connection.

If an event handler directly accesses these resources, it stops being pure and, consequently, it becomes harder to test, etc. So we don't want that.

Instead, the interceptor created by this function is a way to 'inject' 'necessary resources' into the :coeffects (map) subsequently given to the event handler at call time.

See also reg-cofx

Given an `id`, and an optional, arbitrary `value`, returns an interceptor
whose `:before` adds to the `:coeffects` (map) by calling a pre-registered
'coeffect handler' identified by the `id`.

The previous association of a `coeffect handler` with an `id` will have
happened via a call to `day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/reg-cofx` - generally on program startup.

Within the created interceptor, this 'looked up' `coeffect handler` will
be called (within the `:before`) with two arguments:

- the current value of `:coeffects`
- optionally, the originally supplied arbitrary `value`

This `coeffect handler` is expected to modify and return its first, `coeffects` argument.

**Example of `inject-cofx` and `reg-cofx` working together**


First - Early in app startup, you register a `coeffect handler` for `:datetime`:

    #!clj
    (day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/reg-cofx
      :datetime                        ;; usage  (inject-cofx :datetime)
      (fn coeffect-handler
        [coeffect]
        (assoc coeffect :now (js/Date.))))   ;; modify and return first arg

Second - Later, add an interceptor to an -fx event handler, using `inject-cofx`:

    #!clj
    (day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/reg-event-fx            ;; when registering an event handler
      :event-id
      [ ... (inject-cofx :datetime) ... ]  ;; <-- create an injecting interceptor
      (fn event-handler
        [coeffect event]
          ;;... in here can access (:now coeffect) to obtain current datetime ...
        )))

**Background**

`coeffects` are the input resources required by an event handler
to perform its job. The two most obvious ones are `db` and `event`.
But sometimes an event handler might need other resources.

Perhaps an event handler needs a random number or a GUID or the current
datetime. Perhaps it needs access to a DataScript database connection.

If an event handler directly accesses these resources, it stops being
pure and, consequently, it becomes harder to test, etc. So we don't
want that.

Instead, the interceptor created by this function is a way to 'inject'
'necessary resources' into the `:coeffects` (map) subsequently given
to the event handler at call time.

See also `reg-cofx`
sourceraw docstring

make-restore-fnclj/s

(make-restore-fn)

This is a utility function, typically used in testing.

It checkpoints the current state of re-frame and returns a function which, when later called, will restore re-frame to the checkpointed state.

The checkpoint includes app-db, all registered handlers and all subscriptions.

This is a utility function, typically used in testing.

It checkpoints the current state of re-frame and returns a function which, when
later called, will restore re-frame to the checkpointed state.

The checkpoint includes `app-db`, all registered handlers and all subscriptions.
sourceraw docstring

on-changesclj/s

(on-changes f out-path & in-paths)

Returns an interceptor which will observe N paths within db, and if any of them test not identical? to their previous value (as a result of a event handler being run), then it will run f to compute a new value, which is then assoc-ed into the given out-path within db.

Example Usage:

#!clj
(defn my-f
  [a-val b-val]
  ... some computation on a and b in here)

;; use it
(def my-interceptor (on-changes my-f [:c] [:a] [:b]))

(reg-event-db
  :event-id
  [... my-interceptor ...]  ;; <-- ultimately used here
  (fn [db v]
     ...))

If you put this Interceptor on handlers which might change paths :a or :b, it will:

  • call f each time the value at path [:a] or [:b] changes
  • call f with the values extracted from [:a] [:b]
  • assoc the return value from f into the path [:c]
Returns an interceptor which will observe N paths within `db`, and if any of them
test not `identical?` to their previous value  (as a result of a event handler
being run), then it will run `f` to compute a new value, which is then assoc-ed
into the given `out-path` within `db`.

Example Usage:

    #!clj
    (defn my-f
      [a-val b-val]
      ... some computation on a and b in here)

    ;; use it
    (def my-interceptor (on-changes my-f [:c] [:a] [:b]))

    (reg-event-db
      :event-id
      [... my-interceptor ...]  ;; <-- ultimately used here
      (fn [db v]
         ...))


If you put this Interceptor on handlers which might change paths `:a` or `:b`,
it will:

  - call `f` each time the value at path `[:a]` or `[:b]` changes
  - call `f` with the values extracted from `[:a]` `[:b]`
  - assoc the return value from `f` into the path  `[:c]`
sourceraw docstring

pathclj/s

(path & args)

Returns an interceptor which acts somewhat like clojure.core/update-in, in the sense that the event handler is given a specific part of app-db to change, not all of app-db.

The interceptor has both a :before and :after functions. The :before replaces the :db key within coeffects with a sub-path within app-db. The :after reverses the process, and it grafts the handler's return value back into db, at the right path.

Examples:

#!clj
(path :some :path)
(path [:some :path])
(path [:some :path] :to :here)
(path [:some :path] [:to] :here)

Example Use:

#!clj
(reg-event-db
  :event-id
  (path [:a :b])  ;; <-- used here, in interceptor chain
  (fn [b v]       ;; 1st arg is not db. Is the value from path [:a :b] within db
    ... new-b))   ;; returns a new value for that path (not the entire db)

Notes:

  1. path may appear more than once in an interceptor chain. Progressive narrowing.
  2. if :effects contains no :db effect, can't graft a value back in.
Returns an interceptor which acts somewhat like `clojure.core/update-in`, in the sense that
the event handler is given a specific part of `app-db` to change, not all of `app-db`.

The interceptor has both a `:before` and `:after` functions. The `:before` replaces
the `:db` key within coeffects with a sub-path within `app-db`. The `:after` reverses the process,
and it grafts the handler's return value back into db, at the right path.

Examples:

    #!clj
    (path :some :path)
    (path [:some :path])
    (path [:some :path] :to :here)
    (path [:some :path] [:to] :here)

Example Use:

    #!clj
    (reg-event-db
      :event-id
      (path [:a :b])  ;; <-- used here, in interceptor chain
      (fn [b v]       ;; 1st arg is not db. Is the value from path [:a :b] within db
        ... new-b))   ;; returns a new value for that path (not the entire db)

Notes:

  1. `path` may appear more than once in an interceptor chain. Progressive narrowing.
  2. if `:effects` contains no `:db` effect, can't graft a value back in.
sourceraw docstring

purge-event-queueclj/s

(purge-event-queue)

Removes all events currently queued for processing

Removes all events currently queued for processing
sourceraw docstring

reg-cofxclj/s

(reg-cofx id handler)

Register the given coeffect handler for the given id, for later use within inject-cofx:

  • id is keyword, often namespaced.
  • handler is a function which takes either one or two arguements, the first of which is always coeffects and which returns an updated coeffects.

See also: inject-cofx

Register the given coeffect `handler` for the given `id`, for later use
within `inject-cofx`:

  - `id` is keyword, often namespaced.
  - `handler` is a function which takes either one or two arguements, the first of which is
     always `coeffects` and which returns an updated `coeffects`.

See also: `inject-cofx`
sourceraw docstring

reg-event-ctxclj/s

(reg-event-ctx id handler)
(reg-event-ctx id interceptors handler)

Register the given event handler (function) for the given id. Optionally, provide an interceptors chain:

  • id is typically a namespaced keyword (but can be anything)
  • handler is a function: context-map -> context-map

You can explore what is provided in context here.

Example Usage:

#!clj
(reg-event-ctx
  :event-id
  (fn [{:keys [coeffects] :as context}]
    (let [initial  {:db     (:db coeffects)
                    :event  (:event coeffects)
                    :fx     []}
          result   (-> initial
                     function1
                     function2
                     function3)
          effects  (selectkeys result [:db :fx])]
       (assoc context :effects effects))))
Register the given event `handler` (function) for the given `id`. Optionally, provide
an `interceptors` chain:

  - `id` is typically a namespaced keyword  (but can be anything)
  - `handler` is a function: context-map -> context-map

You can explore what is provided in `context` [here](https://day8.github.io/re-frame/Interceptors/#what-is-context).

Example Usage:

    #!clj
    (reg-event-ctx
      :event-id
      (fn [{:keys [coeffects] :as context}]
        (let [initial  {:db     (:db coeffects)
                        :event  (:event coeffects)
                        :fx     []}
              result   (-> initial
                         function1
                         function2
                         function3)
              effects  (selectkeys result [:db :fx])]
           (assoc context :effects effects))))
sourceraw docstring

reg-event-dbclj/s

(reg-event-db id handler)
(reg-event-db id interceptors handler)

Register the given event handler (function) for the given id. Optionally, provide an interceptors chain:

  • id is typically a namespaced keyword (but can be anything)
  • handler is a function: (db event) -> db
  • interceptors is a collection of interceptors. Will be flattened and nils removed.

Example Usage:

#!clj
(reg-event-db
  :token
  (fn [db event]
    (assoc db :some-key (get event 2)))  ;; return updated db

Or perhaps:

#!clj
(reg-event-db
  :namespaced/id           ;; <-- namespaced keywords are often used
  [one two three]          ;; <-- a seq of interceptors
  (fn [db [_ arg1 arg2]]   ;; <-- event vector is destructured
    (-> db
      (dissoc arg1)
      (update :key + arg2))))   ;; return updated db
Register the given event `handler` (function) for the given `id`. Optionally, provide
an `interceptors` chain:

  - `id` is typically a namespaced keyword  (but can be anything)
  - `handler` is a function: (db event) -> db
  - `interceptors` is a collection of interceptors. Will be flattened and nils removed.

Example Usage:

    #!clj
    (reg-event-db
      :token
      (fn [db event]
        (assoc db :some-key (get event 2)))  ;; return updated db

Or perhaps:

    #!clj
    (reg-event-db
      :namespaced/id           ;; <-- namespaced keywords are often used
      [one two three]          ;; <-- a seq of interceptors
      (fn [db [_ arg1 arg2]]   ;; <-- event vector is destructured
        (-> db
          (dissoc arg1)
          (update :key + arg2))))   ;; return updated db
sourceraw docstring

reg-event-fxclj/s

(reg-event-fx id handler)
(reg-event-fx id interceptors handler)

Register the given event handler (function) for the given id. Optionally, provide an interceptors chain:

  • id is typically a namespaced keyword (but can be anything)
  • handler is a function: (coeffects-map event-vector) -> effects-map
  • interceptors is a collection of interceptors. Will be flattened and nils removed.

Example Usage:

#!clj
(reg-event-fx
  :event-id
  (fn [cofx event]
    {:db (assoc (:db cofx) :some-key (get event 2))}))   ;; return a map of effects

Or perhaps:

#!clj
(reg-event-fx
  :namespaced/id           ;; <-- namespaced keywords are often used
  [one two three]          ;; <-- a seq of interceptors
  (fn [{:keys [db] :as cofx} [_ arg1 arg2]] ;; destructure both arguments
    {:db       (assoc db :some-key arg1)          ;; return a map of effects
     :dispatch [:some-event arg2]}))
Register the given event `handler` (function) for the given `id`. Optionally, provide
an `interceptors` chain:

  - `id` is typically a namespaced keyword  (but can be anything)
  - `handler` is a function: (coeffects-map event-vector) -> effects-map
  - `interceptors` is a collection of interceptors. Will be flattened and nils removed.


Example Usage:

    #!clj
    (reg-event-fx
      :event-id
      (fn [cofx event]
        {:db (assoc (:db cofx) :some-key (get event 2))}))   ;; return a map of effects


Or perhaps:

    #!clj
    (reg-event-fx
      :namespaced/id           ;; <-- namespaced keywords are often used
      [one two three]          ;; <-- a seq of interceptors
      (fn [{:keys [db] :as cofx} [_ arg1 arg2]] ;; destructure both arguments
        {:db       (assoc db :some-key arg1)          ;; return a map of effects
         :dispatch [:some-event arg2]}))
sourceraw docstring

reg-fxclj/s

(reg-fx id handler)

Register the given effect handler for the given id:

  • id is keyword, often namespaced.
  • handler is a side-effecting function which takes a single argument and whose return value is ignored.

To use, first, associate :effect2 with a handler:

#!clj
(reg-fx
   :effect2
   (fn [value]
      ... do something side-effect-y))

Then, later, if an event handler were to return this effects map:

#!clj
{:effect2  [1 2]}

then the handler fn we registered previously, using reg-fx, will be called with an argument of [1 2].

Register the given effect `handler` for the given `id`:

  - `id` is keyword, often namespaced.
  - `handler` is a side-effecting function which takes a single argument and whose return
    value is ignored.

To use, first, associate `:effect2` with a handler:

    #!clj
    (reg-fx
       :effect2
       (fn [value]
          ... do something side-effect-y))

Then, later, if an event handler were to return this effects map:

    #!clj
    {:effect2  [1 2]}

then the `handler` `fn` we registered previously, using `reg-fx`, will be
called with an argument of `[1 2]`.
sourceraw docstring

reg-global-interceptorclj/s

(reg-global-interceptor interceptor)

Registers the given interceptor as a global interceptor. Global interceptors are included in the processing chain of every event.

When you register an event handler, you have the option of supplying an interceptor chain. Any global interceptors you register are effectively prepending to this chain.

Global interceptors are run in the order that they are registered.

Registers the given `interceptor` as a global interceptor. Global interceptors are
included in the processing chain of every event.

When you register an event handler, you have the option of supplying an
interceptor chain. Any global interceptors you register are effectively
prepending to this chain.

Global interceptors are run in the order that they are registered.
sourceraw docstring

reg-subclj/s

(reg-sub query-id & args)

A call to reg-sub associates a query-id WITH two functions.

The two functions provide 'a mechanism' for creating a node in the Signal Graph. When a node of type query-id is needed, the two functions can be used to create it.

The three arguments are:

  • query-id - typically a namespaced keyword (later used in subscribe)
  • optionally, an input signals function which returns the input data flows required by this kind of node.
  • a computation function which computes the value (output) of the node (from the input data flows)

Later, during app execution, a call to (subscribe [:sub-id 3 :blue]), will trigger the need for a new :sub-id Signal Graph node (matching the query [:sub-id 3 :blue]). And, to create that node the two functions associated with :sub-id will be looked up and used.

Just to be clear: calling reg-sub does not immediately create a node. It only registers 'a mechanism' (the two functions) by which nodes can be created later, when a node is bought into existence by the use of subscribe in a View Function.

The computation function is expected to take two arguments:

  • input-values - the values which flow into this node (how is it wierd into the graph?)
  • query-vector - the vector given to subscribe

and it returns a computed value (which then becomes the output of the node)

When computation function is called, the 2nd query-vector argument will be that vector supplied to the subscribe. So, if the call was (subscribe [:sub-id 3 :blue]), then the query-vector supplied to the computaton function will be [:sub-id 3 :blue].

The argument(s) supplied to reg-sub between query-id and the computation-function can vary in 3 ways, but whatever is there defines the input signals part of the mechanism, specifying what input values "flow into" the computation function (as the 1st argument) when it is called.

So, reg-sub can be called in one of three ways, because there are three ways to define the input signals part. But note, the 2nd method, in which a signals function is explicitly supplied, is the most canonical and instructive. The other two are really just sugary variations.

First variation - no input signal function given:

#!clj
(reg-sub
  :query-id
  a-computation-fn)   ;; has signature:  (fn [db query-vec]  ... ret-value)

In the absence of an explicit signals function, the node's input signal defaults to app-db and, as a result, the value within app-db (a map) is is given as the 1st argument when a-computation-fn is called.

Second variation - a signal function is explicitly supplied:

#!clj
(reg-sub
  :query-id
  signal-fn     ;; <-- here
  computation-fn)

This is the most canonical and instructive of the three variations.

When a node is created from the template, the signal function will be called and it is expected to return the input signal(s) as either a singleton, if there is only one, or a sequence if there are many, or a map with the signals as the values.

The current values of the returned signals will be supplied as the 1st argument to the a-computation-fn when it is called - and subject to what this signal-fn returns, this value will be either a singleton, sequence or map of them (paralleling the structure returned by the signal function).

This example signal function returns a 2-vector of input signals.

#!clj
(fn [query-vec dynamic-vec]
   [(subscribe [:a-sub])
    (subscribe [:b-sub])])

The associated computation function must be written to expect a 2-vector of values for its first argument:

#!clj
(fn [[a b] query-vec]     ;; 1st argument is a seq of two values
  ....)

If, on the other hand, the signal function was simpler and returned a singleton, like this:

#!clj

(fn [query-vec dynamic-vec] (subscribe [:a-sub])) ;; <-- returning a singleton

then the associated computation function must be written to expect a single value as the 1st argument:

#!clj
(fn [a query-vec]       ;; 1st argument is a single value
   ...)

Further Note: variation #1 above, in which an input-fn was not supplied, like this:

#!clj
(reg-sub
  :query-id
  a-computation-fn)   ;; has signature:  (fn [db query-vec]  ... ret-value)

is the equivalent of using this 2nd variation and explicitly suppling a signal-fn which returns app-db:

#!clj
(reg-sub
  :query-id
  (fn [_ _]  re-frame/app-db)   ;; <--- explicit signal-fn
  a-computation-fn)             ;; has signature:  (fn [db query-vec]  ... ret-value)

Third variation - syntax Sugar

#!clj
(reg-sub
  :a-b-sub
  :<- [:a-sub]
  :<- [:b-sub]
  (fn [[a b] query-vec]    ;; 1st argument is a seq of two values
    {:a a :b b}))

This 3rd variation is just syntactic sugar for the 2nd. Instead of providing an signals-fn you provide one or more pairs of :<- and a subscription vector.

If you supply only one pair a singleton will be supplied to the computation function, as if you had supplied a signal-fn returning only a single value:

#!clj
(reg-sub
  :a-sub
  :<- [:a-sub]
  (fn [a query-vec]      ;; only one pair, so 1st argument is a single value
    ...))

For further understanding, read the tutorials, and look at the detailed comments in /examples/todomvc/src/subs.cljs.

See also: subscribe

A call to `reg-sub` associates a `query-id` WITH two functions.

The two functions provide 'a mechanism' for creating a node
in the Signal Graph. When a node of type `query-id` is needed,
the two functions can be used to create it.

The three arguments are:

- `query-id` - typically a namespaced keyword (later used in subscribe)
- optionally, an `input signals` function which returns the input data
  flows required by this kind of node.
- a `computation function` which computes the value (output) of the
  node (from the input data flows)

Later, during app execution, a call to `(subscribe [:sub-id 3 :blue])`,
will trigger the need for a new `:sub-id` Signal Graph node (matching the
query `[:sub-id 3 :blue]`). And, to create that node the two functions
associated with `:sub-id` will be looked up and used.

Just to be clear: calling `reg-sub` does not immediately create a node.
It only registers 'a mechanism' (the two functions) by which nodes
can be created later, when a node is bought into existence by the
use of `subscribe` in a `View Function`.

The `computation function` is expected to take two arguments:

  - `input-values` - the values which flow into this node (how is it wierd into the graph?)
  - `query-vector` - the vector given to `subscribe`

and it returns a computed value (which then becomes the output of the node)

When `computation function` is called, the 2nd `query-vector` argument will be that
vector supplied to the `subscribe`. So, if the call was `(subscribe [:sub-id 3 :blue])`,
then the `query-vector` supplied to the computaton function will be `[:sub-id 3 :blue]`.

The argument(s) supplied to `reg-sub` between `query-id` and the `computation-function`
can vary in 3 ways, but whatever is there defines the `input signals` part
of `the mechanism`, specifying what input values "flow into" the
`computation function` (as the 1st argument) when it is called.

So, `reg-sub` can be called in one of three ways, because there are three ways
to define the input signals part. But note, the 2nd method, in which a
`signals function` is explicitly supplied, is the most canonical and
instructive. The other two are really just sugary variations.

**First variation** - no input signal function given:

    #!clj
    (reg-sub
      :query-id
      a-computation-fn)   ;; has signature:  (fn [db query-vec]  ... ret-value)

   In the absence of an explicit `signals function`, the node's input signal defaults to `app-db`
   and, as a result, the value within `app-db` (a map) is
   is given as the 1st argument when `a-computation-fn` is called.


**Second variation** - a signal function is explicitly supplied:

    #!clj
    (reg-sub
      :query-id
      signal-fn     ;; <-- here
      computation-fn)

This is the most canonical and instructive of the three variations.

When a node is created from the template, the `signal function` will be called and it
is expected to return the input signal(s) as either a singleton, if there is only
one, or a sequence if there are many, or a map with the signals as the values.

The current values of the returned signals will be supplied as the 1st argument to
the `a-computation-fn` when it is called - and subject to what this `signal-fn` returns,
this value will be either a singleton, sequence or map of them (paralleling
the structure returned by the `signal function`).

This example `signal function` returns a 2-vector of input signals.

    #!clj
    (fn [query-vec dynamic-vec]
       [(subscribe [:a-sub])
        (subscribe [:b-sub])])

The associated computation function must be written
to expect a 2-vector of values for its first argument:

    #!clj
    (fn [[a b] query-vec]     ;; 1st argument is a seq of two values
      ....)

If, on the other hand, the signal function was simpler and returned a singleton, like this:

    #!clj
   (fn [query-vec dynamic-vec]
     (subscribe [:a-sub]))      ;; <-- returning a singleton

then the associated computation function must be written to expect a single value
as the 1st argument:

    #!clj
    (fn [a query-vec]       ;; 1st argument is a single value
       ...)

Further Note: variation #1 above, in which an `input-fn` was not supplied, like this:

    #!clj
    (reg-sub
      :query-id
      a-computation-fn)   ;; has signature:  (fn [db query-vec]  ... ret-value)

is the equivalent of using this
2nd variation and explicitly suppling a `signal-fn` which returns `app-db`:

    #!clj
    (reg-sub
      :query-id
      (fn [_ _]  re-frame/app-db)   ;; <--- explicit signal-fn
      a-computation-fn)             ;; has signature:  (fn [db query-vec]  ... ret-value)

**Third variation** - syntax Sugar

    #!clj
    (reg-sub
      :a-b-sub
      :<- [:a-sub]
      :<- [:b-sub]
      (fn [[a b] query-vec]    ;; 1st argument is a seq of two values
        {:a a :b b}))

This 3rd variation is just syntactic sugar for the 2nd.  Instead of providing an
`signals-fn` you provide one or more pairs of `:<-` and a subscription vector.

If you supply only one pair a singleton will be supplied to the computation function,
as if you had supplied a `signal-fn` returning only a single value:

    #!clj
    (reg-sub
      :a-sub
      :<- [:a-sub]
      (fn [a query-vec]      ;; only one pair, so 1st argument is a single value
        ...))

For further understanding, read the tutorials, and look at the detailed comments in
/examples/todomvc/src/subs.cljs.

See also: `subscribe`
sourceraw docstring

reg-sub-rawclj/s

(reg-sub-raw query-id handler-fn)

This is a low level, advanced function. You should probably be using reg-sub instead.

Some explanation is available in the docs at <a href="http://day8.github.io/re-frame/flow-mechanics/" target="_blank">http://day8.github.io/re-frame/flow-mechanics/</a>

This is a low level, advanced function.  You should probably be
using `reg-sub` instead.

Some explanation is available in the docs at
<a href="http://day8.github.io/re-frame/flow-mechanics/" target="_blank">http://day8.github.io/re-frame/flow-mechanics/</a>
sourceraw docstring

register-handlerclj/sdeprecated

(register-handler & args)

Deprecated. Use reg-event-db instead.

Deprecated. Use `reg-event-db` instead.
sourceraw docstring

register-subclj/sdeprecated

(register-sub & args)

Deprecated. Use reg-sub-raw instead.

Deprecated. Use `reg-sub-raw` instead.
sourceraw docstring

remove-post-event-callbackclj/s

(remove-post-event-callback id)

Unregisters a post event callback function, identified by id.

Such a function must have been previously registered via add-post-event-callback

Unregisters a post event callback function, identified by `id`.

Such a function must have been previously registered via `add-post-event-callback`
sourceraw docstring

set-loggers!clj/s

(set-loggers! new-loggers)

re-frame outputs warnings and errors via the API function console which, by default, delegates to js/console's default implementation for log, error, warn, debug, group and groupEnd. But, using this function, you can override that behaviour with your own functions.

The argument new-loggers should be a map containing a subset of they keys for the standard loggers, namely :log :error :warn :debug :group or :groupEnd.

Example Usage:

#!clj
(defn my-logger      ;; my alternative logging function
  [& args]
  (post-it-somewhere (apply str args)))

;; now install my alternative loggers
(day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/set-loggers!  {:warn my-logger :log my-logger})
re-frame outputs warnings and errors via the API function `console`
 which, by default, delegates to `js/console`'s default implementation for
`log`, `error`, `warn`, `debug`, `group` and `groupEnd`. But, using this function,
 you can override that behaviour with your own functions.

The argument `new-loggers` should be a map containing a subset of they keys
for the standard `loggers`, namely  `:log` `:error` `:warn` `:debug` `:group`
or `:groupEnd`.

Example Usage:

    #!clj
    (defn my-logger      ;; my alternative logging function
      [& args]
      (post-it-somewhere (apply str args)))

    ;; now install my alternative loggers
    (day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/set-loggers!  {:warn my-logger :log my-logger})
 
sourceraw docstring

subscribeclj/s

(subscribe query)
(subscribe query dynv)

Given a query vector, returns a Reagent reaction which will, over time, reactively deliver a stream of values. So, in FRP-ish terms, it returns a Signal.

To obtain the current value from the Signal, it must be dereferenced:

#!clj
(let [signal (subscribe [:items])
      value  (deref signal)]     ;; could be written as @signal
  ...)

which is typically written tersely as simple:

#!clj
(let [items  @(subscribe [:items])]
  ...)

query is a vector of at least one element. The first element is the query-id, typically a namespaced keyword. The rest of the vector's elements are optional, additional values which parameterise the query performed.

dynv is an optional 3rd argument, which is a vector of further input signals (atoms, reactions, etc), NOT values. This argument exists for historical reasons and is borderline deprecated these days.

Example Usage:

#!clj
(subscribe [:items])
(subscribe [:items "blue" :small])
(subscribe [:items {:colour "blue"  :size :small}])

Note: for any given call to subscribe there must have been a previous call to reg-sub, registering the query handler (functions) associated with query-id.

Hint

When used in a view function BE SURE to deref the returned value. In fact, to avoid any mistakes, some prefer to define:

#!clj
(def <sub  (comp deref day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/subscribe))

And then, within their views, they call (<sub [:items :small]) rather than using subscribe directly.

De-duplication

Two, or more, concurrent subscriptions for the same query will source reactive updates from the one executing handler.

See also: reg-sub

Given a `query` vector, returns a Reagent `reaction` which will, over
time, reactively deliver a stream of values. So, in FRP-ish terms,
it returns a `Signal`.

To obtain the current value from the Signal, it must be dereferenced:

    #!clj
    (let [signal (subscribe [:items])
          value  (deref signal)]     ;; could be written as @signal
      ...)

 which is typically written tersely as simple:

    #!clj
    (let [items  @(subscribe [:items])]
      ...)


`query` is a vector of at least one element. The first element is the
`query-id`, typically a namespaced keyword. The rest of the vector's
elements are optional, additional values which parameterise the query
performed.

`dynv` is an optional 3rd argument, which is a vector of further input
signals (atoms, reactions, etc), NOT values. This argument exists for
historical reasons and is borderline deprecated these days.

**Example Usage**:

    #!clj
    (subscribe [:items])
    (subscribe [:items "blue" :small])
    (subscribe [:items {:colour "blue"  :size :small}])

Note: for any given call to `subscribe` there must have been a previous call
to `reg-sub`, registering the query handler (functions) associated with
`query-id`.

**Hint**

When used in a view function BE SURE to `deref` the returned value.
In fact, to avoid any mistakes, some prefer to define:

    #!clj
    (def <sub  (comp deref day8.re-frame-10x.inlined-deps.re-frame.v1v1v2.re-frame.core/subscribe))

And then, within their views, they call  `(<sub [:items :small])` rather
than using `subscribe` directly.

**De-duplication**

Two, or more, concurrent subscriptions for the same query will
source reactive updates from the one executing handler.

See also: `reg-sub`
sourceraw docstring

trim-vclj/s

An interceptor which removes the first element of the event vector, before it is supplied to the event handler, allowing you to write more aesthetically pleasing event handlers. No leading underscore on the event-v!

Should you want the full original event, it can be found in coeffects under the key :original-event.

Your event handlers will look like this:

#!clj
(reg-event-db
  :event-id
  [... trim-v ...]    ;; <-- added to the interceptors
  (fn [db [x y z]]    ;; <-- instead of [_ x y z]
    ...)
An interceptor which removes the first element of the event vector,
before it is supplied to the event handler, allowing you to write more
 aesthetically pleasing event handlers. No leading underscore on the event-v!

Should you want the full original event, it can be found in `coeffects` under
the key `:original-event`.

Your event handlers will look like this:

    #!clj
    (reg-event-db
      :event-id
      [... trim-v ...]    ;; <-- added to the interceptors
      (fn [db [x y z]]    ;; <-- instead of [_ x y z]
        ...)
  
sourceraw docstring

unwrapclj/s

New in v1.2.0

An interceptor which decreases the amount of destructuring necessary in an event handler where the event is structured as a 2-vector of [event-id payload-map].

It promotes the payload-map part to be the event ultimately given to the event handler. Should you want the full original event, it can be found in coeffects under the key :original-event.

If a dispatch looked like this:

#!clj (dispatch [:event-id {:x 1 :y 2 :z 3}])

Your event handlers can look like this:

#!clj (reg-event-fx :event-id [... unwrap ...] ;; <-- added to the interceptors (fn [{:keys [db]} {:keys [x y z]}] ;; <-- instead of [_ {:keys [x y z]}] ...)

> New in v1.2.0

An interceptor which decreases the amount of destructuring necessary in an
event handler where the event is structured as a 2-vector of
[event-id payload-map].

It promotes the `payload-map` part to be the event ultimately given to the
event handler. Should you want the full original event, it can be found in
`coeffects` under the key `:original-event`.

If a dispatch looked like this:

   #!clj
    (dispatch [:event-id {:x 1 :y 2 :z 3}])

Your event handlers can look like this:

   #!clj
    (reg-event-fx
      :event-id
      [... unwrap ...]                    ;; <-- added to the interceptors
      (fn [{:keys [db]} {:keys [x y z]}]  ;; <-- instead of [_ {:keys [x y z]}]
        ...)
sourceraw docstring

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