request: import once functionality

[TxHawks]

An import-once functionality in the default, reference and dynamic loaders would be really nice.

See node-sass-import-once and eyeglass's import-once

[davidkpiano]

I'll be releasing this soon! Here's a proof of concept: https://github.com/davidkpiano/sassport/blob/master/src/modules/once.js

You can actually straight up use this module right now:

var importOnce = require('sassport/lib/modules/once');

//...

sassport([ importOnce ]).render(...);

Then in your SCSS:

@import 'some-partial !once';

// ...

[TxHawks]

Is it possible to define once as the default behavior? And is it possible to mix loaders?

I mean do something like

@import 'some-partial !once !reference';

Sorry for the barrage of questions

[davidkpiano]

It's definitely possible to use multiple loaders, and they will run left to right: https://github.com/davidkpiano/sassport/blob/master/test/loaders.js#L52

So your example will work, and it will first run it through once and then through reference.

I can definitely see having a defaultLoaders configuration, what do you think?

sassport([ once, reference ], {
  defaultLoaders: ['once']
}).render(...);

[TxHawks]

Looks really good.

[TxHawks]

I assume the import-once functionality is not yet available in the version that's NPM, right?

[davidkpiano]

It actually is available, just not documented: https://github.com/davidkpiano/sassport/blob/master/test/loaders.js#L86

But I will be making a separate package for this module, most likely called sassport-once.

[TxHawks]

Would this work with sub-dependencies? I think this would be the most interesting use case, as it would enable efficient modules.

The scenario is in mind is this:

// _module-a.scss
@import `node_modules/module-b`;

// styles.scss
@import `node_modules/module-a`;
@import `node_modules/module-b`;

ideally, an import-once loader should recognize the module-b was already imported inside module-a and not import it again in style.scss

[davidkpiano]

Yes, it will. In Sass, importing is a blocking synchronous action, meaning that this sequence of imports will happen:

• import module-a (current stack: [module-a])
  • import module-b (current stack: [module-a, module-b])
• skip module-b since it was already imported by checking current stack

[TxHawks]

👍