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add findpackage

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Maximilian Keßler 2021-09-08 20:52:52 +02:00
parent afea68386c
commit 13699cacca
1 changed files with 48 additions and 0 deletions
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mkessler-findpackage.sty Normal file
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\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{mkessler-findpackage}[2021-09-06 - Find a package that provides some command]
%%%%
% This is just a quick packaging of the post by
% 'Martin Nyolt' (https://tex.stackexchange.com/users/78783/martin-nyolt)
% found at
% https://tex.stackexchange.com/users/78783/martin-nyolt
% Note that SO answers are by default CC BY-SA 3.0 licensed, see
% https://creativecommons.org/licenses/by-sa/3.0/
\def\find@load#1[#2]#3[#4]{%
% load the package
\find@fileswith@pti@ns{#1}[#2]{#3}[#4]%
% check if commands exists now
\ifcsname\find@command\endcsname
\typeout{Package #3 introduces command \find@command.}%
% command has been found, revert to original version without checks
\let\@fileswith@pti@ns\find@fileswith@pti@ns
\else
% somehow, \@fileswith@pti@ns is restored after loading a package
% thus, patch it again
\let\@fileswith@pti@ns\find@load
\fi
}%
\newcommand*{\findpackagebycommand}[1]{%
% using this multiple times - esp. when the package has not been found yet -
% will break things. Thus, check first that \find@command has never been defined before
\ifx\find@command\undefined
\def\find@command{#1}%
% first, check if this command is already defined
\ifcsname\find@command\endcsname
% in this case, just issue a warning and do nothing
\@latex@warning@no@line{Command \find@command \space is already defined}%
\else
% overwrite the internal \@fileswith@pti@ns command, which does the actual loading
% \@fileswith@pti@ns is used internally by \usepackage and \RequirePackage
\let\find@fileswith@pti@ns\@fileswith@pti@ns
\let\@fileswith@pti@ns\find@load
\fi
\else
% used multiple times - prevent and give a warning
\@latex@warning@no@line{You can use \protect\findpackagebycommand \space only once}%
\errmessage{Invalid use of command findpackagebycommand.}%
\fi
}