Thomas,
This is one of many little twists I see between languages where one feature
impacts use or even the need for another feature.
So can anyone point to places in Python where a semicolon is part of a best
or even good way to do anything?
Some older languages had simple parsers/compilers that needed some way to
know when a conceptual line of code was DONE and the semi-colon was a choice
for making that clear. But some languages seem to only continue looking past
an end-of-line if they detect some serious reason to assume you are in
middle of something. An unmatched open parenthesis or square bracket might
be enough, and in some languages a curly brace.
Python mainly has a concept of indentation and blank lines as one part of
the guidance. Continuing lines is possible, if done carefully.
But consider the lowly comma. Some languages may assume more is to come if
it is dangled at the end of a line. But in a language that supports a
dangling comma such as in making a tuple, how is the interpreter to know
more is to come?
>>> a = 5,
>>> a
(5,)
>>> a = 5, \
... 6
>>> a
(5, 6)
Well, one possible use of a semi-colon is to make short one-liner functions
like this:
def twoByFour(a): sq = a*a; forth = sq*sq; return((sq, forth))
There is no reason, of course, that could not be done in multiple indented
lines or other ways.
So if it was allowed in something like a lambda creation, it could be useful
but it isn't!
About the only thing that I can think of is if someone wishes to compress a
file of python code a bit. The indentation can add up but a semi-colon does
not solve all such problems.
Would anything serious break if it was deprecated for use as a statement
terminator? Then again, is it hurting anything? If it stopped being used
this way, could it later be introduced as some new language feature or
operator such as we now have a := b as a reuse of the colon, maybe a
semicolon could be useful at least until someone decides to allow additional
Unicode characters!
Now if there are serious reasons to use semi-colon in python, great. If not,
it is a historical artifact.
-----Original Message-----
From: Python-list <python-list-bounces+avi.e.gross=gmail.com@python.org> On
Behalf Of Thomas Passin
Sent: Wednesday, February 22, 2023 7:24 PM
To: python-list@python.org
Subject: Re: Introspecting the variable bound to a function argument
On 2/22/2023 3:12 PM, Hen Hanna wrote:
> On Wednesday, February 22, 2023 at 2:32:57 AM UTC-8, Anton Shepelev wrote:
>> Hello, all.
>>
>> Does Python have an instrospection facility that can determine to
>> which outer variable a function argument is bound, e.g.:
>>
>> v1 = 5;
>> v2 = 5;
>
>
> do some Python coders like to end lines with ; ?
Very few, probably. It's not harmful but adds unnecessary visual clutter.
>>
>> def f(a):
>> print(black_magic(a)) # or
black_magic('a')
>>
>> f(v1) # prints: v1
>> f(v2) # prints: v2
>>
>
> the term [call by name] suggests this should be possible.
>
>
> 30 years ago... i used to think about this type of thing A LOT ---
> ------- CBR, CBV, CBN, (call by value), (call by name)....
etc.
>
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https://mail.python.org/mailman/listinfo/python-list
This is one of many little twists I see between languages where one feature
impacts use or even the need for another feature.
So can anyone point to places in Python where a semicolon is part of a best
or even good way to do anything?
Some older languages had simple parsers/compilers that needed some way to
know when a conceptual line of code was DONE and the semi-colon was a choice
for making that clear. But some languages seem to only continue looking past
an end-of-line if they detect some serious reason to assume you are in
middle of something. An unmatched open parenthesis or square bracket might
be enough, and in some languages a curly brace.
Python mainly has a concept of indentation and blank lines as one part of
the guidance. Continuing lines is possible, if done carefully.
But consider the lowly comma. Some languages may assume more is to come if
it is dangled at the end of a line. But in a language that supports a
dangling comma such as in making a tuple, how is the interpreter to know
more is to come?
>>> a = 5,
>>> a
(5,)
>>> a = 5, \
... 6
>>> a
(5, 6)
Well, one possible use of a semi-colon is to make short one-liner functions
like this:
def twoByFour(a): sq = a*a; forth = sq*sq; return((sq, forth))
There is no reason, of course, that could not be done in multiple indented
lines or other ways.
So if it was allowed in something like a lambda creation, it could be useful
but it isn't!
About the only thing that I can think of is if someone wishes to compress a
file of python code a bit. The indentation can add up but a semi-colon does
not solve all such problems.
Would anything serious break if it was deprecated for use as a statement
terminator? Then again, is it hurting anything? If it stopped being used
this way, could it later be introduced as some new language feature or
operator such as we now have a := b as a reuse of the colon, maybe a
semicolon could be useful at least until someone decides to allow additional
Unicode characters!
Now if there are serious reasons to use semi-colon in python, great. If not,
it is a historical artifact.
-----Original Message-----
From: Python-list <python-list-bounces+avi.e.gross=gmail.com@python.org> On
Behalf Of Thomas Passin
Sent: Wednesday, February 22, 2023 7:24 PM
To: python-list@python.org
Subject: Re: Introspecting the variable bound to a function argument
On 2/22/2023 3:12 PM, Hen Hanna wrote:
> On Wednesday, February 22, 2023 at 2:32:57 AM UTC-8, Anton Shepelev wrote:
>> Hello, all.
>>
>> Does Python have an instrospection facility that can determine to
>> which outer variable a function argument is bound, e.g.:
>>
>> v1 = 5;
>> v2 = 5;
>
>
> do some Python coders like to end lines with ; ?
Very few, probably. It's not harmful but adds unnecessary visual clutter.
>>
>> def f(a):
>> print(black_magic(a)) # or
black_magic('a')
>>
>> f(v1) # prints: v1
>> f(v2) # prints: v2
>>
>
> the term [call by name] suggests this should be possible.
>
>
> 30 years ago... i used to think about this type of thing A LOT ---
> ------- CBR, CBV, CBN, (call by value), (call by name)....
etc.
>
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https://mail.python.org/mailman/listinfo/python-list
--
https://mail.python.org/mailman/listinfo/python-list
