Conditional compilation

[gissehel]

This is an enhancement I would like to see on coffee-script.

I have two profiles Development/Production (or call them Debug/Release). In Development/Debug profile, I'm including directly the coffee script into the html page (as well as less css code). In Production/Release, I'm including javascript and css generated once.

What I would like is a way to include some javascript code lines only in development/debug profile, and not even use a "if" at run time. something like :

firstcall()
[DEBUG]console.log "firstcall has been called"
secondcall()

that would compile to :

firstcall();
console.log("firstcall has been called");
secondcall();

in "DEBUG" profile (with "DEBUG" beeing "defined" at compile time)
and compile to :

firstcall();
secondcall();

"DEBUG" could then be passed as option in the script tag as well as a parameter on the command line.

the syntax [DEBUG] is just an example and could be @@debug@@ or %DEBUG% I don't really care.

Of course, writing :

firstcall()
if DEBUG
    console.log "firstcall has been called"
secondcall()

could achieve the same goal, except I don't want the "if" to be executed at run time.

[jashkenas]

Thanks for the ticket, but I'm afraid we won't be adding conditional compilation to CoffeeScript. Feel free to strip stuff out of your codebase before compiling, if you like.

[davispuh]

why not? I think it would be really great feature, besides it wouldn't matter to those who wouldn't use it...

I think easiest way making it would be exactly like it is in C (adding preprocessor support #1466)

#ifndef release
#define debug true
#endif

#ifdef debug
console.log "Debug info..."
#endif

(where #define variable could be given with compiler flag eg. coffee -d release=true -c -o lib/ src/)

using C style preprocessor wouldn't make any incompatibilities with older compilers as # is comment and it would be ignored (obvious blocks inside #ifdef's would always be included...)

preprocessor/macro is really MUST HAVE feature which could be used in really a lot of ways. Also it doesn't really matter if other syntax is used, but there need one. And always can rework/rewrite if something was done incorrectly.

[ajrouvoet]

+1

[loveencounterflow]

@davispuh i sincerely hope you do not mean to suggest introducing C-style preprocessor macros into CS. they're full of edge cases and pitfalls. if what you mean to say is "i want to have syntactic macros in CS" then +1.

[vendethiel]

@loveencounterflow Seen BlackCoffee ?

[loveencounterflow]

yes, and sadly, i can't extend the syntax of CS with BC...