The exact syntax of Python's if name equals main construct ... the code associated with the if condition would execute. If the file was imported as a module, the code would not run. The if name equals ...

As shown below, you can use the field function for ... condition): if condition == "Unacceptable": self.shelf_id = None else: self.shelf_id = 0 But not every Python class needs to be a dataclass.

While Python has lacked a native syntax for pattern matching ... or any of those plus conditional expressions. Any matches that are ambiguous or impossible to resolve will throw an exception ...