[Python-Dev] Declaring setters with getters (original) (raw)

glyph at divmod.com glyph at divmod.com
Thu Nov 1 18:26:52 CET 2007

On 02:01 pm, guido at python.org wrote:

On 10/31/07, glyph at divmod.com <glyph at divmod.com> wrote:

As long as we're all tossing out ideas here, my 2ยข. I vastly prefer this: >> @property.set to this: > @property.set(attribute)

I don't approve of it. It has always been and will always continue to be my position that these are semantically unkosher, because it means that you can't wrap them in convenience functions or invoke them in different contexts, and that means that the semantics are hard to explain.

Point taken.

If you really want another argument, repeating the property name actually does have an additional use case: you can have a read-only property with a corresponding read-write property whose name differs.

I don't actually have this use-case, but it does make the actual semantics of the provided argument a bit clearer to me. It's not an implementation detail of fusing the properties together, it's just saying which property to get the read accessor from.

This is a minor nit, as with all decorators that take an argument, it seems like it sets up a hard-to-debug error condition if you were to accidentally forget it:

@property
def foo(): ...
@property.set
def foo(): ...

would leave you with 'foo' pointing at something that wasn't a descriptor at all. Is there a way to make that more debuggable?

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