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Re: A desperate lunge for on-topic-ness

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  Re: A desperate lunge for on-topic-ness Dave Angel <d@davea.name> - 2012-10-18 12:47 -0400
    Re: A desperate lunge for on-topic-ness Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-19 01:20 +0000
      Re: A desperate lunge for on-topic-ness Dave Angel <d@davea.name> - 2012-10-18 22:00 -0400

#31665 — Re: A desperate lunge for on-topic-ness

On 10/18/2012 12:26 PM, Chris Angelico wrote:
> On Fri, Oct 19, 2012 at 3:16 AM, Evan Driscoll <driscoll@cs.wisc.edu> wrote:
>>    Python isn't as bad as C++ though (my main other language), where
>>    80 characters can go by *very* quickly.
>>
>> 2. Backslash continuations are *terrible*. I hate them with a firery
>>    passion. :-) A line could be 1000 characters long and it would be
>>    better than a 120-character line backslash-continued.
> I have one mid-sized C++ project at work that's pretty much
> exclusively under my control. There is precisely ONE place where
> backslash continuations crop up, and that's long strings that want to
> be formatted on multiple lines (eg huge SQL statements) - in Python,
> they'd be trip-quoted. We don't have *any* backslash continuations in
> Python code.
>
>

But both C++ and Python have automatic concatenation of adjacent
strings.  So you can just start and end each line with a quote, and
leave off the backslash.

Similarly, if you need a newline at the end of each line, you can use
the \n just before the trailing quote.  Naturally I agree with you that
this case is better handled in Python with triple-quote.

I never use the backslash at end-of-line to continue a statement to the
next.  Not only is it a readability problem, but if your editor doesn't
have visible spaces, you can accidentally have whitespace after the
backslash, and wonder what went wrong.

-- 

DaveA

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#31699

On Thu, 18 Oct 2012 12:47:48 -0400, Dave Angel wrote:

> I never use the backslash at end-of-line to continue a statement to the
> next.  Not only is it a readability problem, but if your editor doesn't
> have visible spaces, you can accidentally have whitespace after the
> backslash, and wonder what went wrong.

What, you don't read the SyntaxError that you will invariably get?


# Python 2.7 and 3.3:

py> x = 42 + \
  File "<stdin>", line 1
    x = 42 + \
              ^
SyntaxError: unexpected character after line continuation character



Even if you go back to truly ancient Python 1.5:

[steve@ando ~]$ python1.5
Python 1.5.2 (#1, Aug 27 2012, 09:09:18)  [GCC 4.1.2 20080704 (Red Hat 
4.1.2-52)] on linux2
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>> x = 42 + \
  File "<stdin>", line 1
    x = 42 + \
              ^
SyntaxError: invalid token


Honestly, it's not that hard to diagnose line continuation errors. It's 
probably easier to diagnose them than to diagnose missing parentheses.

The more I hear people dissing line continuation backslashes, the more I 
want to use them everywhere.


-- 
Steven

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#31707

On 10/18/2012 09:20 PM, Steven D'Aprano wrote:
> On Thu, 18 Oct 2012 12:47:48 -0400, Dave Angel wrote:
>
>> I never use the backslash at end-of-line to continue a statement to the
>> next.  Not only is it a readability problem, but if your editor doesn't
>> have visible spaces, you can accidentally have whitespace after the
>> backslash, and wonder what went wrong.
> What, you don't read the SyntaxError that you will invariably get?
>
>
> # Python 2.7 and 3.3:
>
> py> x = 42 + \
>   File "<stdin>", line 1
>     x = 42 + \
>               ^
> SyntaxError: unexpected character after line continuation character
>
>
>
> Even if you go back to truly ancient Python 1.5:
>
> [steve@ando ~]$ python1.5
> Python 1.5.2 (#1, Aug 27 2012, 09:09:18)  [GCC 4.1.2 20080704 (Red Hat 
> 4.1.2-52)] on linux2
> Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>>> x = 42 + \
>   File "<stdin>", line 1
>     x = 42 + \
>               ^
> SyntaxError: invalid token
>
>
> Honestly, it's not that hard to diagnose line continuation errors. It's 
> probably easier to diagnose them than to diagnose missing parentheses.
>
> The more I hear people dissing line continuation backslashes, the more I 
> want to use them everywhere.

The context was both C++ and python, and I got into the habit of
avoiding the continuation characters in C++, where the compiler usually
has a totally stupid error, if any.

it's been so long since I've used them, it's quite possible I never
tried it in python.


-- 

DaveA

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