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Spread a statement over various lines


On 17.09.19 20:59, Manfred Lotz wrote:
> I have a function like follows
> 
> def regex_from_filepat(fpat):
>     rfpat = fpat.replace('.', '\\.') \
>                       .replace('%', '.')  \
>                       .replace('*', '.*')
> 
>     return '^' + rfpat + '$'
> 
> 
> As I don't want to have the replace() functions in one line my
> question is if it is ok to spread the statement over various lines as
> shown above, or if there is a better way?
> 

One problem with explicit line continuation using \ is that it is
dependent on the backslash being the last character on the line, i.e.
a single space at the end of the line will result in a SyntaxError.
This is why implicit line continuation relying on opened parentheses,
brackets or curly braces is often preferred, and recommended over
backslash continuation in PEP8
(https://www.python.org/dev/peps/pep-0008/#maximum-line-length).
To use implicit line continuation you could either introduce extra
surrounding parentheses as suggested by others, or you may make use
of the parentheses you have already, like so:

def regex_from_filepat(fpat):
    rfpat = fpat.replace(
        '.', '\\.'
    ).replace(
        '%', '.'
    ).replace(
        '*', '.*'
    )

    return '^' + rfpat + '$'