Many re methods accepted the string parameter as a keyword argument by wrong name. This was fixed inissue20283. Wrong keyword names were still accepted, but a deprecation warning was emitted if use them. Proposed patch finishes the deprecation period (started since 3.4) and removes the support of wrong names.Python 2.7.7, 3.3.6, 3.4-3.6:>>> import re>>> re.compile('.').match(pattern='a')__main__:1: DeprecationWarning: The 'pattern' keyword parameter name is deprecated.  Use 'string' instead.<_sre.SRE_Match object; span=(0, 1), match='a'>>>> re.compile('.').match(string='a')<_sre.SRE_Match object; span=(0, 1), match='a'>Python 3.7:>>> re.compile('.').match(pattern='a')Traceback (most recent call last):  File "<stdin>", line 1, in <module>TypeError: Required argument 'string' (pos 1) not found

It's too bad that "pattern" lost out to the less informative "string".+1 for finishing the work and applying this patch.

"pattern" is not more informative, it is just wrong. The argument of the match() method is not a pattern, it is a string with which a pattern is matched.

New changesetf8678135c042 by Serhiy Storchaka in branch 'default':Issue#29195: Removed support of deprecated undocumented keyword argumentshttps://hg.python.org/cpython/rev/f8678135c042