[Python-ideas] Python reviewed

[Ned Batchelder]

On 1/9/17 8:44 PM, Simon Lovell wrote:
>
> Also in Python you can use:
>
> for x in range (1,j+1):
>
> to loop j times. Although it does read as though it is looping j+1
> times to those not familiar.
>
> One more comment I wanted to make about end blocks, is that a
> respectable editor will add them for you, together with the
> indentation of the next line. EditPlus 2 did it best in my experience
> although I think I just haven't seen a well configured alternative. I
> very rarely forget the block closer but I do sometimes forget the colon.
>
> Regarding the logical inconsistency of my argument, well I am saying
> that I would prefer my redundancy at the end of the loop rather than
> the beginning. To say that the status quo is better is to say that you
> prefer your redundancy at the beginning. Fair enough, I'm happy to
> respect your opinion there. I still struggle to see why it should be
> mandatory though? For those who prefer to have the block closing
> delimiters this way, is the need for a keyword (could be a command
> line option) really the objection?
>

Can you clarify something for us? Are you proposing to add end-block
syntax?  You've said you prefer it, and that you miss it. But you
haven't said, "I am proposing that Python should change."  This list is
about proposing changes to Python.  Are you proposing that Python change
in this way?

You understand that this is a significant shift from a syntax that has
been in place for a quarter century? Perhaps you should give yourself
time to get used to Python as Python is.

--Ned.

>
> I'll have a detailed look at your colon link a bit later.
>
>
> On 10/01/17 09:26, Chris Barker wrote:
>> On Mon, Jan 9, 2017 at 5:12 PM, Simon Lovell <simon58500 at bigpond.com
>> <mailto:simon58500 at bigpond.com>> wrote:
>>
>>     Re: Counters starting at zero vs one, Fortran has a neat solution
>>     to this for arrays if not strings - allow the programmer to
>>     select the starting index.
>>
>>
>> I liked that back in the day, but I think it's really better if it's
>> always the same.
>>
>> and see my other note for why the zero-based and open ended slicing
>> is fabulous -- indexing really needs to match slicing.
>>
>> ONe more:
>>
>> since you mentioned Fortran -- it's a common use-case for an array to
>> model some sort of regular spaced grid, so:
>>
>> x = start_x + i*delta_x
>>
>> really easy and logical math for figuring out where you are on a grid
>> (and the reverse calculation) -- this is a pain with 1-based indexing....
>>
>> (of course, C does this for pointer math for the same reason...)
>>
>>     When I've programmed for loops in C, sometimes you want zero
>>     based and sometimes one based, while most times you don't really
>>     care. To make it readable I would wherever possible write either:
>>         for (i=0;i<j;i++)
>>         for (i=1;i<=j;i++)  // In both cases always executing j times
>>
>>
>> in pyton, you never right that code anyway. most of the time, it's 
>>
>> for item in sequence:
>>
>> no indexes at all.
>>
>> or:
>>
>> for i in range(N):
>>   ...
>>
>> indexes, but you dont care
>>
>> or 
>>
>> for i, item in enumerate(seq):
>>     ...
>>
>> or for item1, item2 in zip(sequence):
>>     ...
>>
>> i.e you almost never care what the starting index is!
>>
>> -CHB
>>
>>
>>
>>  
>>
>>     Rgds
>>
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>>
>>
>> -- 
>>
>> Christopher Barker, Ph.D.
>> Oceanographer
>>
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>
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