Why and how "there is only one way to do something"?

Steve Holden steve at holdenweb.com
Thu Dec 15 15:57:18 CET 2005

Ben Sizer wrote:
> Steve Holden wrote:
>>Would you, say, remove "for" loops because they could be written as
>>"while" loops. Don't forget the word "obvious" that appears in that
>>catchphrase ...
> Interestingly - and somewhat related to this - the other day I was
> looking for a do..while or do..until loop in the Python language
> reference, thinking that there must be a statement for it, since
> semantically they're distinct from while loops. I had a use case that
> could have been slightly simplified by such a construct. The fact that
> I didn't find one seemed slightly strange at first, coming from a
> C/Pascal background, although it did occur to me that I've used Python
> for years now and not noticed this lack before.
You'll find it's exercised the group frequently from time to time. 
Without wishing to stir the whole thing up again, the essence of the 
problem is the unnatural fit with Python's suite design.

Would you say

     while condition

or what? Basically do ... while and do ... until most naturally put the 
test after the loop body (suite), and it's difficult to think of a 
consistent and natural syntax for expressing the construct. Not that 
this stopped lots of people from coming forward with their personal 
favourites ... some suggestions even offered "n and a half" looping 

In the end nobody managed to convince Guido that a suitable solution was 
readily to hand, so nothing happened.

Steve Holden       +44 150 684 7255  +1 800 494 3119
Holden Web LLC                     www.holdenweb.com
PyCon TX 2006                  www.python.org/pycon/

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