Most elegant way to do something N times

[Avi Gross]

What others have answered is tangential. Nobody doubts there are places
where you want to repeat something N times. Just to add an example, if you
are parsing something nested by parentheses or perhaps HTML, and you reach a
point where you have seen N opening symbols and start seeing a closing
symbols, you might want to swallow the next N-1 such symbols before moving
on to whatever comes next. Yes, I know that can be more complex.

But in many such cases, people do not just count lines or whatever, but
actively examine each line. This is especially true where it is valid to
have say a comment embedded or other things that make the count uncertain.

Again, what language does something simpler?

Example, in R, is this much better?

for(n_times in 1:6) {print("hi")}
[1] "hi"
[1] "hi"
[1] "hi"
[1] "hi"
[1] "hi"
[1] "hi"

Using R, again, you can make a repeat function that calls your designated
function with a fizxed argument N times:

repetito = function(n, func, arg) {
  for (i in 1:n) {
    func(arg)
  }
}

 repetito(6, print, "hi")
[1] "hi"
[1] "hi"
[1] "hi"
[1] "hi"
[1] "hi"
[1] "hi"

Python allows similar ways:

>>> def repetito(n, func, args) :
	for _ in range(n):
		func(args)

		
>>> repetito(6, print, "hi")
hi
hi
hi
hi
hi
hi

You can modify these ideas to having no arguments or multiple arguments or
even varying numbers of arguments with varying numbers of positional and
keyword arguments. You need to be careful at times to make sure that the
calls are not evaluated once but each time.

I suspect the request boils down to wanting yet another keyword or two added
to a language that does not need more bloat.


-----Original Message-----
From: Python-list <python-list-bounces+avigross=verizon.net at python.org> On
Behalf Of DL Neil via Python-list
Sent: Monday, December 23, 2019 7:27 PM
To: Python <python-list at python.org>
Subject: Re: Most elegant way to do something N times

On 24/12/19 1:04 PM, Chris Angelico wrote:
> On Tue, Dec 24, 2019 at 10:45 AM Marco Sulla <elbarbun at gmail.com> wrote:
>>
>>>
>>> I encounter with cases like doing a function 6 time with no 
>>> argument, or same arguments over and over or doing some structral 
>>> thing N times and I dont know how elegant I can express that to the
code.
>>>
>>
>> ??? Excuse me, but why you needed to call the same function SIX 
>> times? This seems to me not elegant in primis.
>>
>> Can you give us a practical example?

Taking the top/bottom six from a sorted list of occurrences.

eg in Accounts Payable, a clerk might be given the task of 'chasing' the six
largest debtors (people who owe us money), as today's work
assignment/priority.


> File parsing. You read a section header and want to ignore that 
> section, so you ignore the next 15 lines.

(just to be cheeky to @Chris)

Perhaps better as a Finite State Machine, with one state being 'seeking
section header'.
1 can we guarantee that the 'magic constant' of 15 will always apply?
2 presumably the total routine will involve more than identifying a single
header and skipping (only) that section.
--
Regards =dn
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