Support interfaces

[simPod]

I'm trying to generate classes for InterfaceType and it seems not to be supported in ClassGenerator. Is it intentional?

selection is like

interfacetype {
    somefield
}

but I'm crashing on

sailor/src/Codegen/ClassGenerator.php

Line 251 in 77ba145

throw new \Exception('Unsupported type '.get_class($namedType).' found.');

Unsupported type GraphQL\Type\Definition\InterfaceType found.

Thanks

[spawnia]

Yeah, interfaces are not supported yet. I will probably add support as soon as I have a use case for them. If you want to contribute, I am open to reviewing and aiding in the implementation of this feature.

[simPod]

Hmm. So what if we add methods to generated classes that represent Object types and let them implement interfaces representing Interface types for shared fields?

[spawnia]

The generated result objects allow access to fields in the form of properties. I think this is more elegant than methods because:

• it allows null-safe access with ?? (this will be less imporant with PHP 8 null safe method calls ?->)
• no need to type an extra set of parantheses
• easy setup of mocked results for test by just setting the properties

That said, interfaces without methods still provide value:

• while they cannot define properties, they can indeed define virtual properties via @property. We will have to check how this interacts when the implementing object type narrows a field type, e.g. changing it to be non-nullable
• it can be used as a strong type hint

[simPod]

I see the PR, just few notes on those interfaces.

easy setup of mocked results for test by just setting the properties

methods would read properties so the same applies, no?

it allows null-safe access with ??

method calls do so? or I don't understand

---

Implemented interfaces only with properties seem a bit dirty as it is not how the language was designed

[spawnia]

Given this code:

class Foo {
    public ?Foo $bar;
    function bar(): ?Foo { return null; }
}

$foo = new Foo;

The following will work without error:

$foo->bar->bar ?? null;

This will throw with Fatal error: Uncaught Error: Call to undefined function bar():

$foo->bar()->bar() ?? null;

PHP 8 would allow to do it safely and succintly, but even then properties are more terse:

$foo->bar()?->bar();

[simPod]

Ah ok I see what you meant by that. I go with PHP 8 everywhere.