Named regular expression group P group name regexp what does P stand for

Question

In Python  the   P lt group name gt      syntax allows one to refer to the matched string through its name    gt  gt  gt  import re  gt  gt  gt  match   re search    P lt name gt       P lt phone gt        John 123456    gt  gt  gt  match group  name    John    What does  P  stand for   I could not find any hint in the official documentation   I would love to get ideas about how to help my students remember this syntax  Knowing what  P  does stand for  or might stand for  would be useful

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Pattern   The group names a  sub pattern for later use in the regex   See the documentation here for details about how such groups are used

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Python Extension   From the Python Docs   The solution chosen by the Perl developers was to use        as the extension syntax    immediately after a parenthesis was a syntax error because the   would have nothing to repeat  so this didn   t introduce any compatibility problems  The characters immediately after the   indicate what extension is being used  so    foo  is one thing  a positive lookahead assertion  and    foo  is something else  a non-capturing group containing the subexpression foo   Python supports several of Perl   s extensions and adds an extension syntax to Perl   s extension syntax If the first character after the question mark is a P  you know that it   s an extension that   s specific to Python  https   docs python org 3 howto regex html

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Since we re all guessing  I might as well give mine  I ve always thought it stood for Python   That may sound pretty stupid -- what  P for Python   -- but in my defense  I vaguely remembered this thread  emphasis mine       Subject   Claiming   P     regex syntax extensions      From  Guido van Rossum  gui    CNRI Reston Va US       Date  Dec 10  1997 3 36 19 pm      I have an unusual request for the Perl developers  those that develop   the Perl language    I hope this  perl5-porters  is the right list   I   am cc ing the Python string-sig because it is the origin of most of   the work I m discussing here       You are probably aware of Python   I am Python s creator  I am   planning to release a next  major  version  Python 1 5  by the end of   this year   I hope that Python and Perl can co-exist in years to come    cross-pollination can be good for both languages    I believe Larry   had a good look at Python when he added objects to Perl 5  O Reilly   publishes books about both languages        As you may know  Python 1 5 adds a new regular expression module that   more closely matches Perl s syntax   We ve tried to be as close to the   Perl syntax as possible within Python s syntax   However  the regex   syntax has some Python-specific extensions  which all begin with   P     Currently there are two of them         P lt foo gt      Similar to regular grouping parentheses  but the text   matched by the group is accessible after the match has been performed    via the symbolic group name  foo          P foo  Matches the same string as that matched by the group named     foo    Equivalent to  1   2  etc  except that the group is referred   to by name  not number       I hope that this Python-specific extension won t conflict with any   future Perl extensions to the Perl regex syntax   If you have plans to   use   P  please let us know as soon as possible so we can resolve the   conflict   Otherwise  it would be nice if the   P syntax could be   permanently reserved for Python-specific syntax extensions    Is   there  some kind of registry of extensions     to which Larry Wall replied              There s no registry as of now--yours is the first request from   outside perl5-porters  so it s a pretty low-bandwidth activity      Sorry it was even lower last week--I was off in New York at Internet   World        Anyway  as far as I m concerned  you may certainly have  P  with my   blessing   Obviously Perl doesn t need the  P  at this point   -          So I don t know what the original choice of P was motivated by -- pattern  placeholder  penguins  -- but you can understand why I ve always associated it with Python   Which considering that  1  I don t like regular expressions and avoid them wherever possible  and  2  this thread happened fifteen years ago  is kind of odd

[python] Named regular expression group "(?P<group_name>regexp)": what does "P" stand for?

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