EP 003 - View Registration

Status: Placeholder. Only scribbles. Don't read yet.

Abstract

Broadbrush:

• views will be registered via a new re-frame.core/def-view function
• like other re-frame registration functions, def-view associates a keyword with a (reagent) render function
• the registered view keyword (eg: :my-view) can be used in hiccup to identify the renderer. eg: [:my-view "Hello world"]
• def-view allows various values to be injected as args into the view render
• see https://github.com/reagent-project/reagent/issues/362

Why:

• removing (render) functions from hiccup will make hiccup even more data oriented. Symptoms include helping with various state machine ideas.
• injection of dispatch and subscribe will help view functions to be slightly more pure. dispatch still kinda a problem.
• ijection of context which will help with "multiple re-frame apps on the one page" problem

What might need to be injected (as args) into a view:

• subscribe and dispatch
• a frame supplied via context (subscribe and dispatch obtained from frame)
• other context: data from higher in the DOM tree
• annimation? CSS ?

XXX searches up the DOM heirarchy looking for a frame context then extracts dispatch and subscribe. Sounds inefficient.

Code Doodle #1

Associate the keyword :my-view-id with a renderer using def-view:

(def-view 
   :my-view-id 
   
   ;; indicate what `context` is required
   [:dispatch :subscribe :context XXX] 
          
   ;; the renderer
   ;; last argument `context` is a map of:
   ;;    - `:subs` - a vector of subscription values? 
   ;;    - :dispatch and :subscribe 
   ;;    - :context - a vector of context values
   ;; 
   (fn [a-str context]
     (let [XXXX] 
       )))

Use of :my-view-id:

[:my-view-id  "Hello"] 

Code Doodle #2

Associate the keyword :my-view-id with a renderer using def-view:

(def-view 
   :my-view-id 
   
   ;; injection function
   ;; indicate what subscriptions we wish to obtain 
   ;; obtain a dispatch for use 
   ;; get the context id if you want to 
   ;; 
   :subscriptions 
   (fn [_ id]
      {:subs [[:item ]] 
       :context ["name1", "name2")})

       
   ;; the renderer
   ;; last argument `ins` is a map of:
   ;;    - `:subs` - a vector of subscription values? 
   ;;    - :dispatch and :subscribe 
   ;;    - :context - a vector of context values
   ;; 
   (fn [a-str  ins]
     (let [XXXX] 
       )))

Use of :my-view-id:

[:my-view-id  "Hello"] 

Code Doodle #3

[:something arg1 arg2]

(def-view 
   :something 
   (fn [arg1 arg2] 
      ;; obtain dispatch and subscription 
      ;; obtain a subscription ot two 
      ;; add a key on the component 
      (fn [arg1 arg2] 
          ))
   

Misc Notes

• reagent hiccup will be changed/monkey-patched so that views can be identified by keyword
• Views are the leaves of the signal graph. They need to subscribe and dispatch.
• how to obtain other pieces of context (beyond the current frame)

XXX There's a nasty problem with frames and subscriptions. How does the signal function know what frame to create new subscriptions against???

Usage