Document side-effects free programmatical usage

[medikoo]

I'd like to use this package programmatically in a script (to recompile some JS files), but with no side effects (e.g. extending natives prototypes or messing with Node.js require system).

The best I probably can get is via:

const nodent = require('nodent')({
  augmentObject: false,
  dontMapStackTraces: true,
  dontInstallRequireHook: true,
});

const compiledSourceCode = nodent.compile(sourceCode, filename, {
  promises: true,
  es7: true,
  noRuntime: true,
  es6target: true,
}).code;

Still if I read correctly, it still implies some side effects:

• Extensions to Function.prototype
• Extensions to global
• Extensions to Object

Is there any chance to obtain a clean run programmaticaly?

[matAtWork]

Short answer, not at the moment, however with the appropriate compile options, such a change could be made - I'll have a go in the next few days. It will restrict the compilation targets; requiring noRuntime and Promises, and would prevent the use of ES7-mode and generators, both of which require runtime support.

You can control the names of the modifications, which should allow you to avoid clashes.

You can also compile via the './nodent.js' script (with the --output option) in a seperate process, which obviously won't modify your runtime.

Is this what you're trying to achieve?

[medikoo]

Is this what you're trying to achieve?

Yes, ideally I want to handle compilation of async/await in scripts which do also other things, and I would prefer that individual tasks do not "leak" undesired changes outside (especially that in that specific case of nodent usage, there's no need for environment changes)

Thanks for answering!

[matAtWork]

Just had a quick look, and right now this is a bit of a mess for legacy reasons. I could possibly provide a secondary "compileOnly" module (as in var compiler = require('nodent/compileOnly'); which would avoid all the legacy guff, but it'll take me a little while. If that works for you, let me know and I'll have a go when I can

[medikoo]

Just had a quick look, and right now this is a bit of a mess for legacy reasons. I could possibly provide a secondary "compileOnly" module (as in var compiler = require('nodent/compileOnly');

Yes, that would be great.

I think it'll be also possible (but not in a clean, straightforward way) if NodentCompiler would be exposed on exported initialize function. Then I guess it'll be possible to setup compiler without calling setGlobalEnvironment ?

[matAtWork]

Actually, that's (also) historic - the Function.prototypes are set in the nodent-runtime module, which is used by a number of third-party apps, so I need a different entry-point to avoid breaking other people's projects.

[matAtWork]

I've pushed a new branch which extracts the compiler into a new file which has no runtime dependency or pollution. It's not published yet, so update your project with:

npm install git://github.com/MatAtBread/nodent#extract-compiler (--save if you want to)

With this revision, you can require nodent/compiler which skips all the runtime inclusion and initialisation.

I have a little test file:

var NodentCompiler = require('nodent/compiler') ;
var c = new NodentCompiler() ;
console.log(c.compile("async () => 1+await x",null,null,{ sourcemap:false, promises: true, noRuntime: true, es6target: true })) ;

Note that it does_not respect the use nodent directive (or package.json options) - it requires you to pass the options in the final parameter of the call to compile(). After all, it's just a compiler. Note also that the code it produces will require nodent-runtime to be present unless you have specified the noRuntime options when compiling. The example above does just that, so the compiled code should run just about anywhere Promises exist.

If this meets your requirements, let me know and I'll do a little tidying up and publish on npm. I'm happy to receive a PR to on that branch to document the new feature too!

[medikoo]

Thanks @matAtWork, looks great. I've tried my best in updating documentation at: #94
Still you will probably want to fine tune that

[matAtWork]

NP. I may well actually separate the CLI, from the core compiler mainly as I like clean dependencies, and the compiler has no dependency on nodent-runtime (and some other stuff like resolve), although as stated it can generate code that does depend on nodent-runtime.

I need to run some further tests and make sure I don't other people's stuff, but hopefully I'll have this ready to go tomorrow. When I have, I'll remove the branch and publish via npm as normal.

[matAtWork]

The compiler has been shipped as the npm module 'nodent-compiler', which has no runtime or global side-effects. 'nodent' has been updated to refer to the compiler as a sub-module, leaving it purely for running the CLI and require hook mechanism. Shipped in https://github.com/MatAtBread/nodent/releases/tag/3.1.0

[medikoo]

Looks great, thank you!