Questions/Explorations about the semantics of command line combinations

What command line args will cause figwheel to autobuild and insert code to establish a repl connection?

For the following examples assume dev.cljs.edn is in the current directory and contains:

{:main example.core}

Acknowledge that there is need to simply autobuild without a server or server connection.

-w src -c example.core

This should autobuild without a server or repl connection. If one wants to supply the compile options resident in a figwheel build config file (i.e. dev.cljs.edn) one can simply pass that config as a normal cljs.main -co flag arg:

-w src -co dev.cljs.edn -c

and the above will not insert any repl or figwheel functionality into the build or build process.

The same is true for a single compile without watching of any kind.

-co dev.cljs.edn -c

and

-c example.core

should only compile once and have no figwheel libraries or other functionality inserted into it.

But once you add a --repl or -serve flag to the operation and the compile :optimizations level is :none then figwheel specific functionality will come into play.

So for a command of:

-co dev.cljs.edn -c -r

Figwheel main will take actions to try and create a figwheel autobuilding development session.

1. a build name dev will be infered from the dev.cljs.edn file name
2. if no configured watch directories are found figwheel.main will try to infer one from the given namespace if it can find it
3. it will insert [figwheel.repl.preload figwheel.core figwheel.main] into the :preloads of the compile options
4. it will add a figwheel.repl/connect-url and perhaps some other configuration into :closure-defines of the compile options
5. it will start a server, repl, and launch a browser to connect to the repl server

When you only ask for a server via:

-co dev.cljs.edn -c -s

A REPL will not be launched but all of the above steps will still be taken.

There is a shortcut main option flag -b or --build which can be used in place of the -c flag.

The following examples are equivalient

-b dev -r  ==  -co dev.cljs.edn -c -r

-b dev -s  ==  -co dev.cljs.edn -c -s

-b dev     ==  -co dev.cljs.edn -c -s

So when you use the --build flag you will normally get a server as well.

How to build once with the --build-once or -bo flag

Background builds and the --bb flag

Turning various features off

How do I better determine the behavior of a set of command line args?

There is a --print-config or -pc init arg which when added to the command line like so:

-pc -co dev.cljs.edn -c example.core -s

Will print out useful information about the resulting configuration.