language design question

[Steven Bethard]

guthrie wrote:
> Steven Bethard wrote:
>> Why would ``x.len()`` be any more convenient than ``len(x)``? Your 
>> preference here seems pretty arbitrary.
> -- Perhaps;
> but having all standard operations as a method seems more regular (to 
> me), and allows a simple chained operation format of a series of method 
> calls, instead of alternating prefix function calls, and post-fix method 
> invocations; e.g.
>       x.lower().strip().toList().sort().join()
> seems cleaner and simpler than the usage below, where the pre/post 
> alternation is visually more complex.
> I think the mix of OO like methods, and global functions, is not ideal.

The advantage of a functional form over a method shows up when you write 
a function that works on a variety of different types. Below are 
implementations of "list()", "sorted()" and "join()" that work on any 
iterable and only need to be defined once::

     def list(iterable):
         result = []
         for item in iterable:
             result.append(item)
         return result

     def sorted(iterable):
         result = list(iterable)
         result.sort()
         return result

     def join(iterable):
         # this is more efficient in C, where the string's buffer can be
         # pre-allocated before iterating through the loop.
         result = ''
         for item in iterable:
             result += item
         return result

Now, by providing these as functions, I only have to write them once, 
and they work on *any* iterable, including some container object that 
you invent tomorrow.

If everything were methods, when you invented your container object 
tomorrow, you'd have to reimplement these methods on your class. (Or 
we'd have to introduce a Container class to provide them, and everyone 
would have to inherit from that if they wanted to define a container.)

>>>   - Why doesn't sort() return a value?
>>>
>>>     This would allow things like:
>>>         key = '',join( list(word.lower().strip()).sort() )
>>
>> Use sorted():
>>
>>     key = ','.join(sorted(word.lower().strip()))
> -- Thanks!
> (Is the comma in ',' just a typo?)

No, the comma puts a comma between each item.  I wasn't sure whether the 
comma in your original was a typo for ''. or for ','.  Of course if you 
don't want the comma between each item, you should just use ''

STeVe