Working with generics and inheritance

[aerogus]

Hi,

I can't understand why my code cant't validate can u help me ?

to reproduce:
https://phpstan.org/r/2a665afc-6b41-4139-a953-10c01a280773

I have a base class "ObjectModel"
I have a single inheritance : class Ccc
I have an double inheritance : class Support and class SupportDvd
In Support there's a property which stores a Ccc object

• ObjectModel
  • Ccc
  • Support (store a Ccc object in a property)
    • SupportDVD

The errors are :

36 	
Generic type Support<SupportDVD> in PHPDoc tag @extends does not specify all template types of class Support: TCcc, TObjectModel
[generics.lessTypes](https://phpstan.org/error-identifiers#gbi-generics.lesstypes)
36 	
Type SupportDVD in generic type Support<SupportDVD> in PHPDoc tag @extends is not subtype of template type TCcc of Ccc of class Support.
[generics.notSubtype](https://phpstan.org/error-identifiers#gbi-generics.notsubtype)

Thx a lot

[ondrejmirtes]

Class Support has two @template tags. When you @extends Support, you need to declare both of them: https://phpstan.org/r/da46f252-61ca-4cd6-9047-8cefcd176313

See:

• https://phpstan.org/blog/generics-in-php-using-phpdocs
• https://phpstan.org/blog/generics-by-examples

[aerogus]

Thanks for your fast reply and the links to the doc.

I had to to some work and revisions because my Support class is not inherited from Ccc. They just have the same ancestor ObjectModel. So certainly I shouldn't have used @template TCcc of Ccc at the top of Support class.

And maybe I don't want Ccc nor Support and SupportDVD to be generic.

[aerogus]

2nd attempt here :

https://phpstan.org/r/2f313391-b917-4a87-add7-38ce48fc161a

Here is my inheritance hierarchy :

• ObjectModel
  • Ccc
  • Format
  • Support
    • SupportDVD

There is an object property in the Support class which contain a Ccc object

but it complains that : Property Support::$ccc with generic class Ccc does not specify its types: TCcc
I can't really understand what's wrong ... :(

[ondrejmirtes]

You've made every class generic by giving them @template but I don't understand why. This just works by removing most of that code: https://phpstan.org/r/56a38c84-96ee-48d6-a91e-642d94990b30

But I'm not even sure why ObjectModel is generic, I'd have to see some methods you have inside it to know if it's justified or not. Because to me it seems like in all your usages, you could just use static.

Please step back and try to explain what are you trying to achieve.

Also please try to read some materials online about generics in general, and also about generics in PHP.

[aerogus]

You are right, I did some refacto in my project and I finally did'n't need any @template or generic !
A lot simpler and no more error.
Thanks for your time and for this project that help me a lot in my debugging !