← index #8273Issue #193
Related · high · value 1.125
QUERY · ISSUE

re module defines re.match both as a function and class

openby Josverlopened 2022-02-07updated 2025-10-03
docs

There appears to be a conflict in both the documentation and the implementation of the re/ure module.

The documentation for the re module specifies that re.match is a function

.. function:: match(regex_str, string)
   Compile *regex_str* and match against *string*. Match always happens
   from starting position in a string.

However it also appears to document that re.match is a class, as there are methods documented.

I would expect that the class would be named Match rather then match

Match objects
-------------
Match objects as returned by `match()` and `search()` methods, and passed
to the replacement function in `sub()`.
.. method:: match.group(index)
   Return matching (sub)string. *index* is 0 for entire match,
   1 and above for each capturing group. Only numeric groups are supported.
.. method:: match.groups()

When checking the implementation ( v1.18) with the below code it appears that there is indeed a class named match returned from the function match.

import re
Substring ='.*Python'
String1 = "MicroPython"
m =re.match(Substring, String1)
print(type(m))
# MicroPython: <class 'match'>
# CPython: <class 're.Match'>

The reason that I noticed this is that I am creating and validating .pyi stubs that are autogenerated from the documentation, and in as part of test and validation noticed this conflict.

Its not to difficult to create another PR to update the documentation, however that would not match the current implementation.
However my main question is: should the implementation be updated to name the class 'Match' ?

CANDIDATE · ISSUE

re match object group() should be equivalent to group(0) according to Python3 documentation

closedby cefnopened 2017-07-05updated 2017-07-05

Trying to port the ijson module to Micropython, I substituted the re module downloaded via upip for the standard re module referenced by ijson.

I found that ijson at line 34 of https://github.com/isagalaev/ijson/blob/master/ijson/backends/python.py relied on the following contract of the match object, by invoking group() with no arguments...

"Without arguments, group1 defaults to zero (the whole match is returned)." ( from https://docs.python.org/3/library/re.html )

Unfortunately the micropython re module doesn't conform. I was able to fix the library by invoking group(0) in the place of group() but ideally the micropython-lib re module would be compliant.

1 comment
pfalcon · 2017-07-05

Thanks for the detailed report, fixed.

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