PyZF

PyZF is Zeff Muks's enhancements for working with Python.

pip install pyzf

Interfaces

Those coming from other languages like Go or TypeScript will be familiar with the concept of interfaces. It enables you to define a contract without worrying about concrete classes. While Python has Abstract Base Classes, there are some limitations:

1. You cannot define optional methods in ABCs
2. It's not easy to compose multiple ABCs
3. Hard to ensure a class implements an ABC

PyZF provides a robust and flexible way to define and implement interfaces in Python. It offers features like interface declarations, default methods, optional methods, and interface composition.

Features

PyZF Interfaces provides a powerful way to define contracts between different parts of your code, improving maintainability and reducing errors.

1. Interface Definition

Define interfaces using the Interface class:

from pyzf.interfaces import Interface, method, default_method, optional_method

class Jedi(Interface):
    @method
    def speak(self) -> str:
        pass

    @method
    def force_power(self) -> int:
        pass

    @default_method
    def default_greet(self) -> str:
        return f"May the Force be with you. I am {self.speak()}"

2. Method Types

In Go, all methods are required but in pyzf, you can define also define optional methods.

• @method: Regular methods that must be implemented
• @default_method: Methods with default implementations
• @optional_method: Methods that can be optionally implemented

3. Interface Composition

Combine multiple interfaces to create more complex ones:

class Sith(Interface):
    @method
    def force_lightning(self) -> None:
        pass

    @optional_method
    def optional_force_choke(self) -> None:
        pass

class ForceUser(Jedi, Sith):
    pass

4. Implementation and Validation

Use the @implements decorator to ensure a class correctly implements an interface:

@implements(ForceUser)
class DarthVader:
    def speak(self) -> str:
        return "I am Darth Vader, Dark Lord of the Sith"

    def force_power(self) -> int:
        return 950

    def force_lightning(self) -> None:
        print("⚡️ Force Lightning!")

In the above example:

• We do not need to implement the default_greet method, as it will be inherited.
• We do not need to implement the optional_force_choke method, as it is optional.

If you try to instantiate a class that does not implement an interface, you will get an InterfaceError.

from pyzf.interfaces import InterfaceError

@implements(ForceUser)
class DarthVader:
    pass

vader = DarthVader() # InterfaceError

In Go, this is equivalent an interface assertion:

var _ ForceUser = (*DarthVader)(nil) # Compiler error if DarthVader does not implement ForceUser

In TypeScript, this is equivalent to an interface assertion:

const vader = new DarthVader(); // Compiler error if DarthVader does not implement ForceUser

5. Usage

Use interfaces for type hinting and polymorphism:

def use_the_force(obj: ForceUser):
    print(f"Type of obj: {type(obj)}")
    print(obj.default_greet())

vader = DarthVader()
use_the_force(vader)

In Go, this is equivalent to:

type ForceUser interface {
    // ...
}

func use_the_force(obj ForceUser)  {  // ForceUser is an interface type
    // ...
}

License

MIT