Twig: [RFC] Added support for classes function

[lyrixx]

The classes function in javascript is quite useful.
Do you think it could be in twig ?
I would port it if you want

[yceruto]

Yes, that's something we need often! I did it for some apps in another way, by adding a custom filter |filter (for PHP: array_filter()) in combination with |keys|join(' '), but definitely a built-in function would be quite useful.

I'm guessing something like this:

<div class="{{ class_names({
    'class1': condition1, 
    'class2': condition2,
    'class3': condition3,
}) }}">
    {# ... #}
</div>

[javiereguiluz]

I like this proposal ... but I'm not a big fan of the proposed function names. Although Twig is for front-end people, it's used by lots of backend people, so "classes" sounds like programming classes, not CSS classes.

Also, front-end people use classes in JavaScript ... so it may be confusing to them too.

What about calling it css_class() ? There's no need to use plural because in Twig we always use singular even when the usage is plural (e.g. include() and not includes())

[gharlan]

Or maybe something more generic, like join (maybe confusing with the existing filter with same name?) or conditional_join, with explicit separator?

<div class="{{ conditional_join(' ', 'a-class', 'another-class', {
    'errored': object.errored,
    'finished': object.finished,
    'pending': object.pending,
}) }}">
</div>

conditional_join(separator, ...args)

[gharlan]

What about calling it css_class() ?

Is it really a "css" class? Isn't it a class for a html element, that can be used in css and js to access that html element?

[lyrixx]

It generates a some css classes.

[fabpot]

Closing the issue so that all the discussion happens on the PR.

[stof]

@lyrixx I think @gharlan is right. It generates HTML classes.