Fix: validate() on forms where is attached non-form component causes error

[ovlach]

• bugfix
• documentation - not needed
• BC break - no

validate() on forms where is attached non-form component causes error - older nette/form using getControls() method where is interface checking.

Now this is not possible, so i create special IValidatable interface which marks controls and container as validatable and checking it.

[fprochazka]

I really like the solution, but I'm not 100% sure if this is not a bc break.

[dg]

Related to 347c545

[milo]

@ovlach The interface is needless here. Can you simplyfied it by adding check that component is form Control or IContainer?

[Majkl578]

I like the interface.
@milo: What you suggest is not correct as it merely relies on the method of same name being present, not enforced by any object contract.

[dg]

Validation will be redesigned in future in another way and this interface is not (will not be) suitable.