Add knowledge to an object from a custom extension

[mvorisek]

Example:

if (!TraitUtil::hasDiContainerTrait($obj)) {
    $obj->setDefaults($injectionActive, false);
}

I want to write an extension for TraitUtil::hasDiContainerTrait to let phpstan know, if cond is true, $obj has specific trait. I cannot use interfaces as traits cannot implement them.

[ondrejmirtes]

There's no way to represent traits in a typesystem for this purpose. You can change the code above to method_exists.

[mvorisek]

The atk4 project uses this heavily (200+ usages).

When the if condition is evaluated, I belive the $obj class is already loaded. Thus in the extension, I can easily go thru all defined classes and return all implementing that trait. But how to update/restrict the $obj type info (in a custom extension) within the if body scope?

[ondrejmirtes]

Best way forward for you is to use an interface. Traits are implementation detail.