[Python-Dev] Shortcut Notation for Chaining Method Calls (original) (raw)

dustin at v.igoro.us dustin at v.igoro.us
Sat Feb 3 20:39:52 CET 2007

On Sat, Feb 03, 2007 at 07:01:47PM +0000, Michael O'Keefe wrote:

Anyhow, just curious for ideas and sparking discussion. ...

I haven't been on the list long enough to know, but I would expect that this idea and its relatives have been batted around at least once before. I think a lot of people have been frustrated at the repetitive nature of operations on lists, for example, as you indicated in your first post. I think there's room for debate on whether specific list methods that currently return None should instead return the list, although I would definitely consult the archives before entering that fray.

I expect that the idea of adding a new operator or any other syntactic change is, like the count of 5, "right out".

For what it's worth, you can wrap an object so it behaves the way you like as follows, although of course this will discard the return value of any functions which produce one:

class wrapcall(object): def init(self, inner): self.inner = inner 

def __getattr__(self, attr):
    rv = getattr(self.inner, attr)
    if callable(rv):
        def wrap(*args, **kwargs):
            rv(*args, **kwargs)
            return self
        return wrap
    else:   
        return rv

mylist = [1, 2, 3] wrapcall(mylist).reverse().append(2).reverse() assert mylist == [2, 1, 2, 3]

Dustin

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