list to string

[Alex Martelli]

"Delaney, Timothy" <tdelaney at avaya.com> wrote in message
news:mailman.983245987.15676.python-list at python.org...
> Indeed.
>
> Personally, I think the join() string method is *really* bad. A method
> should act on the object it is a part of. In this case, there is no
> conceptual way that ''.join(['a', 'b', 'c']) could be considered to be
> acting on '' - it is *using* ''.

And, similarly, it's *using* ['a','b','c'] -- not "acting on" it.  It's not
a mutator.  Not all methods of an object mutate it, and you clearly
accept that, as you write:

> OTOH, ''.length() is perfectly fine. It is obvious.

Since join may use the joiner in a completely polymorphic way, but
only uses the sequence through a sequence-iteration protocol, it's
pragmatically _useful_ to have it be a method of the joiner object
(as Python doesn't do multimethod-like dispatching).  Usefulness
seems to be a good indicator: if something offends your personal
sense of purity, but is pragmatically good, then 'practicality beats
purity' and it might be wise to reconsider your aesthetics:-).


Alex