__EMSCRIPTEN_major/minor/tiny__ defined for compile js ?

[Thaina]

There is an major update about EMVAL related functionality in emscripten in version 2 and 3. And I am in needed to write a js code that can support both version

Something like this

/*global requireHandle, _emval_register, _emval_run_destructors*/

var myLib = {
  JS_GetDate__deps: ['_emval_register'],
  JS_GetDate: function() {
    return __emval_register(new Date());
  },
  
  JS_GetTime__deps: ['$requireHandle'],
  JS_GetTime: function(/** @type {Date} */date) {
    date = requireHandle(date);
    return date.getTime();
  },
  
  JS_Free__deps: ['_emval_run_destructors'],
  JS_Free: function(/** @type {Date} */date) {
    __emval_run_destructors(date);
  },
}

mergeInto(LibraryManager.library,myLib);

I wish I could writing a code like #if EMSCRIPTEN_VERSION < 2.2.0 to switch between code that depend and use _emval_register and code that depend and use use Emval object when anyone bring this code to use in difference emscripten version

/*global requireHandle, _emval_register, _emval_run_destructors*/

var myLib = {
#if EMSCRIPTEN_VERSION < 2.2.0
  JS_GetDate__deps: ['_emval_register'],
#endif
  JS_GetDate: function() {
#if EMSCRIPTEN_VERSION < 2.2.0
    return __emval_register(new Date());
#else
    return Emval.toHandle(new Date());
#endif
  },
  
#if EMSCRIPTEN_VERSION < 2.2.0
  JS_GetTime__deps: ['$requireHandle'],
#endif
  JS_GetTime: function(/** @type {Date} */date) {
#if EMSCRIPTEN_VERSION < 2.2.0
    date = requireHandle(date);
#else
    date = Emval.toValue(date);
#endif
    return date.getTime();
  },
  
  JS_Free__deps: ['_emval_run_destructors'],
  JS_Free: function(/** @type {Date} */date) {
    __emval_run_destructors(date);
  },
}

mergeInto(LibraryManager.library,myLib);

Is it already possible? If not is it could be possible?

Alternatively, are there any compiler flag I could check to see if there is Emval object defined or I need to use _emval_register instead ?

[kripken]

You do have access to EMSCRIPTEN_VERSION in js library files. But it is a string like "3.1.36-git" or "3.1.36", so <, > comparisons would need to go through a helper function I guess.

[Thaina]

It sounds like you are saying that the unity build system allows your to add a --js-libray file, but not two of them? Is that correct?

Unity build system not prohibit appending any arguments to emscripten. But it's not obvious and require fine grain management on the internal build step. It also complicate and can be conflict from many system trying to manage same project

Not to mention unity also have their own internal flag and also internal step I don't know much about (which also seem to changed in each version (and each version of unity sometimes also change the version of emscripten)). The build process also taken place in it's own directory and referencing any file on compiler flag is confusing

That's why it's unwieldy to try messing up the emscripten compiler flag in unity. And so everything should be contained in the script file as much as possible

[Thaina]

@sbc100 OK after experimenting a bit more. I found out that we could actually just write string function directly and so this request is not really needed

#if EMSCRIPTEN_VERSION.split('.').slice(0,4).map(function(n) { return parseInt(n) }) > [2,0,31]
		console.log("{{{EMSCRIPTEN_VERSION}}}" + " > 2.0.31");
#elif EMSCRIPTEN_VERSION.split('.').slice(0,4).map(function(n) { return parseInt(n) }) < [2,0,19]
		console.log("{{{EMSCRIPTEN_VERSION}}}" + " < 2.0.19");
#else
		console.log("{{{EMSCRIPTEN_VERSION}}}" + " >= 2.0.19");
#endif

Thank you very much for giving me all these explanations

[sbc100]

You might also want look into writing your JS code directly in the C/C++ source using EM_JS

[juj]

Thanks for this neat snippet @Thaina . I wonder where the .slice(0,4) part comes from?

I ended up using

#if EMSCRIPTEN_VERSION.split('.').map(parseInt) < [3,1,35]

in my wasm_webgpu bindings library.

[Thaina]

Thanks for this neat snippet @Thaina . I wonder where the .slice(0,4) part comes from?

I ended up using

#if EMSCRIPTEN_VERSION.split('.').map(parseInt) < [3,1,35]

in my wasm_webgpu bindings library.

slice(0,4) means I would pick only 4 item of the split that most likely be a version number to parse as integer