[11.x] Add Blade @var directive

[SanderMuller]

Same idea as #49179 but to add docblocks to improve IDE support like /** var \Namespace\Class $variable */. This is especially useful in Livewire components, Filament views and other Blade files where the IDE can not infer the variable types.

This is only an addition, so shouldn't cause any trouble or disturbance - unless someone has create a custom Blade directive called @var.

A minor addition for convenience when adding extra type information for your IDE in Blade components.

Benefits

• 1 line instead of 3 🔥
• Less code to type ⏱️
• Makes templates look cleaner 🧹

Example (Filament table in this case)

{{-- Before --}}
@php
    /** @var \App\Livewire\Playlist\Index $this */
@endphp

{{-- After --}}
@var(\App\Livewire\Playlist\Index $this)

{{ $this->table }}

Caveats

IDE support won't be there initially for folks, so there will be squigglies.

Credits to @simonhamp for a decent part of this PR description text (based on #49179)

[ahinkle]

Cool idea but I just don't think it fits well for the framework.

@use is a functional directive that affects the runtime behavior whereas the proposed @var is purely for IDE support.

It could also come off as a bit ambiguous, as new developers might think it's actually declaring/defining variables.

[antonkomarev]

Since IDE doesn't understand proposed syntax, I have another idea.

Here is a common comment block:

{{-- @var \App\Livewire\Playlist\Index $this --}}

Much cleaner, will be omitted from the generated PHP template file since it is just a comment.

But we should add this support to IDEs somehow.

[SanderMuller]

Cool idea but I just don't think it fits well for the framework.

@use is a functional directive that affects the runtime behavior whereas the proposed @var is purely for IDE support.

It could also come off as a bit ambiguous, as new developers might think it's actually declaring/defining variables.

You're probably right!

Since IDE doesn't understand proposed syntax, I have another idea.

Here is a common comment block:

{{-- @var \App\Livewire\Playlist\Index $this --}}

Much cleaner, will be omitted from the generated PHP template file since it is just a comment.

But we should add this support to IDEs somehow.

That is indeed a way neater option, which would lie purely in IDE implementation, where this PR's idea would require both Laravel and IDE. The benefit of having it in Laravel is that the IDE will follow to support the Laravel feature (as happened with @use).