Classes

Like Python dataclasses, but magic methods are not supported today.

Declaration

from pypp_python import Val, dataclass


@dataclass
class Greeter:
    name: str
    prefix: Val[str]

    def greet(self) -> str:
        return f"Hello, {self.prefix} {self.name}!"

• In Py++, the first argument of methods must be called self. Other names are not supported.
• The frozen and slots options (i.e. @dataclass(frozen=True, slots=True)) are supported
  • frozen makes the data members const in the generated C++
  • slots does not do anything to change the generated C++ code; it only affects the Python interpreter

Instantiation

from pypp_python import auto


def pseudo_fn():
    # without auto
    bob: str = "Bob"
    greeter1: Greeter = Greeter(bob, "Mr.")

    # with auto
    jane: str = "Jane"
    greeter2: auto = Greeter(jane, "Mrs.")

Factory function pattern

In Py++, you don't define a constructor for the class. If you want instantiation of objects with some other logic, you can use a factory function pattern. An example:

def greeter_mrs_factory(name: str, is_doctor: bool) -> Greeter:
    return Greeter(name, "Dr." if is_doctor else "Mrs.")