Vscode-intelephense: Show suggestions when inside Trait

[mityukov]

Problem

When I'm writing a Trait that is to be used in some class(es) — I'd like to have methods/properties of that class to be suggested.

Example:
```php
// User.php

class User
{
use NotifiableTrait;

protected $email;

public function ban()
{
    $this->notify("You've been banned."); // "notify" is suggested here, which is Good.
}

}

// NotifiableTrait.php
trait NotifiableTrait
{
public function notify($text)
{
Mail::to($this->email)->send(new GenericMessage($text)); // "email" was not suggested here. Which would be nice to do.
}
}
```

Solution

Intelephence to "deduct" in what classes the current trait is used and suggests that classes' props and methods.

At least for the case, when a trait is used in one class only. For "a trait used in many classes" — maybe some visual grouping of suggestions by classes from which they're taken.

[KapitanOczywisty]

People usually don't like to hear that, but in that case you should use abstract methods in trait. Similar issue here: https://github.com/bmewburn/vscode-intelephense/issues/829#issuecomment-563932070

As for suggestions itself, would be nice, but it's probably pain to implement and I wouldn't count on that. Also list of every method where most of them are not relevant to you, would be pretty annoying.

[lepikhinb]

People usually don't like to hear that, but in that case you should use abstract methods in trait. Similar issue here: #829 (comment)

As for suggestions itself, would be nice, but it's probably pain to implement and I wouldn't count on that. Also list of every method where most of them are not relevant to you, would be pretty annoying.

Usually, it's done by setting up @mixin phpdoc, which references the class it has to extend. Unfortunately, intelephense still doesn't support mixins. And there's probably no pain in implementing it.

[lepikhinb]

@bmewburn I see that people keep asking for the feature. Any plans on implementing this? That's the only thing that I miss from phpstorm.

[bmewburn]

IMO traits shouldn't need knowledge of the consuming class. Though, if @mixin will make this work for users that want this functionality then that's reasonable, let's track it in #123

[bmewburn]

Another workaround is to type hint $this using @var.

<?php
// User.php

class User
{
    use NotifiableTrait;

    protected $email;

    public function ban()
    {
        $this->notify("You've been banned."); // "notify" is suggested here, which is Good.
    }
}

// NotifiableTrait.php
trait NotifiableTrait
{
    public function notify($text)
    {
        /** @var User $this */
        Mail::to($this->email)->send(new GenericMessage($text)); // "email" was not suggested here. Which would be nice to do.
    }
}