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Would there be any value to allowing a convention for the __init__() method that allows direct assignment of arguments to attributes? For example, replacing the
by japhyr 10y ago
Would there be any value to allowing a convention for the __init__() method that allows direct assignment of arguments to attributes? For example, replacing the following:
class Point3D(object):
def __init__(self, x, y, z):
self.x = x
self.y = y
self.z = z
with:
class Point3D(object):
def __init__(self, self.x, self.y, self.z):
# Other initialization work
It seems __init__ could be made to parse the list of parameters, and for any self.foo that's not defined, assign the corresponding argument to that attribute. But I have no experience in language design. Is there a reason this wouldn't work?
- m_ke 10y agoyou can just do class B: def __init__(self, a, b, c): self.__dict__.update(locals())
- jsmthrowaway 10y agoYou really, really, really shouldn't do this under any circumstances, though. If you find yourself messing with __dict__ you're down a hole, if you find yourself mutating it you're down an even deeper hole, if you find yourself calling locals() you probably forgot your shovel, and I'd hope that for all of that you'd have a better reason than minimizing code (that's way less readable, for example). I immediately get suspicious when I read code that interacts with __dict__ and I'm only sympathetic if you're cooking a metaclass or something equally arcane. __slots__ also makes __dict__ nonexistent.
- chc 10y agoWell, yeah, but you could implement it without __dict__ just by doing something like: for attr, val in locals().items(): setattr(self, attr, val) It still feels pretty un-Pythonic either way.
- jsmthrowaway 10y agoBecause it is. There is zero reason to be clever here. Yeah, you have to be explicit in __init__. We are all used to it. The "a," "b," "c" examples are disingenuous though because you're often validating, enforcing types, converting, deriving other attributes... __init__ is documentation. I read it to understand what's going on.
- desdiv 10y agoThat makes B.self a field too, which you probably don't want.
- dlbucci 10y agoCoffeeScript has a feature like that, where a constructor can call parameters `@whatever` and they will be assigned to the object. For all the ways CoffeeScript borrows from Python, but somehow makes it worse, that feature is actually very nice/useful (and not super confusing, either).