3 ms·
Just to clarify, I don't mean your article is bad or incomplete -- quite the contrary, I enjoyed it a lot. Generators are one of my favorite Python features and
by qsort 3y ago
Just to clarify, I don't mean your article is bad or incomplete -- quite the contrary, I enjoyed it a lot. Generators are one of my favorite Python features and they're kind of underused, mostly because people simply don't know about them.
A couple more along the same lines:
- Metaclasses and type. (This is admittedly dark magic, but useful in library code, less so in application code)
- Magic methods! Everyone knows about __init__, but you can override all sorts of behaviors (see: https://docs.python.org/3/reference/datamodel.html https://docs.python.org/3/reference/datamodel.html)
My favorite example (I have a lot of favorite examples :)) is __call__, which emulates function calling and is the equivalent of C++'s operator().
Why is it my favorite? Because as the old adage goes, "a class is a poor man's closure, a closure is a poor man's class":
class C:
def __init__(self, x):
self.x = x
def __call__(self, y):
return self.x + y
>>> a = C(2)
>>> a(3)
5
- learplant 3y agoI find that __call__ is very confusing, but maybe because I'm not used to seeing if often. What is the benefit compared to having a method named "add" that also explains the behavior?
- Jtsummers 3y agoIf an object is callable you can use it in places that might conventionally expect functions. The utility of that is very situational, though. I've only used it a handful of times myself over the years I've known and used Python. It may also give you a "clearer" (in quotes because subjective) presentation for something you're trying to do.
- claytonjy 3y agoI see it a lot in HuggingFace, and use it myself for classes that are used like a function, especially when the obvious method name is the verb form of the class name processor = SomeProcessor.load("path/to/config") # with __call__ processed_inputs = processor(inputs) # less awkward than processes_inputs = processor.process(inputs) The only benefit is to the human, same as @property or even @dataclass.
- learplant 3y agoThanks for writing that up! I disagree though, I prefer the processor.process for clarity, and for not adding another way of doing things that regular methods already do.
- erikvdven 3y agoThanks a lot! Really appreciate it. Love the example! Haven't used the dunder __call__ yet (like many magic methods I guess), but that's a nice one! I didn't have to use Metaclasses, either, though I have read about them, especially in Fluent Python. But I guess I belong to the 99% who haven't had to worry about them, yet :P