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Newsgroups: comp.lang.python
Date: Sun, 10 Feb 2013 10:45:13 -0800 (PST)
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Subject: Re: LangWart: Method congestion from mutate multiplicty
From: Rick Johnson <rantingrickjohnson@gmail.com>
Cc: python-list@python.org
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Xref: csiph.com comp.lang.python:38595

On Sunday, February 10, 2013 2:39:21 AM UTC-6, Terry Reedy wrote:
> While it is true that sorted(iterable) is essentially
> 
> def sorted(iterable):
>    tem = list(iterable)
>    tem.sort
>    return tem
> 
> the body is not an expression and cannot be substituted in an 
> expression. 

Yes but the body can be compressed to this single line: "list(iterable).sort()"

> Reversed(iterable) is more complicated because it returns an iterator, 
> not a list, and looks for a class-specific __reversed__ method. 
> [...]

Well if you're taking the position that iterators are difficult to create i say you are exaggerating a bit. Using the for loop:

py> for LOCALVAR in SEQUENCE:
...     do_something

we can get the iterator for free. If however you want to control the iteration /without/ being locked into a loop, you can explicitly call:

py> iter(seq)

Or, if you prefer methods over global functions: 

py> seq.__iter__()

Or, if python employed /true/ OOP paradigm:

py> Iterator(seq)

> Even if list mutation methods returned the list, which they do not and 
> for good reason, 

I am not proposing that in-place modification return the object.

> reversed(it) is not the same as list(it).reverse(). So 
> that part of the premise of this thread is wrong.

Well, it's not the same /now/, because of how Python handles this operation. The status quo is to encourage the implicit idiom over the explicit, however, this behavior could be optimized to cleanly handle /explicit/ syntax only.