[Python-ideas] Add an option for delimiters in bytes.hex()

Steven D'Aprano steve at pearwood.info
Wed May 3 05:20:48 EDT 2017


On Tue, May 02, 2017 at 09:07:41PM -0400, Juancarlo Añez wrote:
> On Tue, May 2, 2017 at 8:43 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> 
> > String methods should return strings.
> >
> 
> >>> "A-B-C".split("-")
> ['A', 'B', 'C']

Yes, thank you. And don't forget:

py> 'abcd'.index('c')
2


But in context, I was responding to the question of why this proposed 
chunk()/group() method returns a string rather than an iterator. I 
worded my answer badly, but the intention was clear, at least in my own 
head *wink*

Given that we were discussing a method that both groups the characters 
of a string and inserts the separators, it makes sense to return a 
string, like other string methods:

'foo'.upper() returns 'FOO', not iter(['F', 'O', 'O'])

'cheese and green eggs'.replace('green', 'red') returns a string, 
    not iter(['cheese and ', 'red', ' eggs'])

'xyz'.zfill(5) returns '00xyz' not iter(['00', 'xyz'])

etc, and likewise:

'abcdef'.chunk(2, sep='-') should return 'ab-cd-ef' rather than
    iter(['ab', '-', 'cd', '-', 'ef'])

If we're talking about a different API, one where only the grouping is 
done and inserting separators is left for join(), then my answer will be 
different. In that case, then it is a matter of taste whether to return 
a list (like split()) or an iterator. I lean slightly towards returning 
a list, but I can see arguments for and against both.


-- 
Steve


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