Xjyuk

I am loading the gitver package based on the expl3 solution accepted for my question here.

However, I need to use some commands depending on whether the package has actually been loaded. For instance, using a combination of hyperxmp, hyperref and gitver, one can provide an option pdfversionid = gitVer to the hypersetup command (see code below).

The question is, how do I conditionally detect the presence of a package loaded (gitver in my example) and set up this conditional compilation?

Minimal conceptual example:

documentclassarticle
usepackageexpl3
csname sys_if_shell_unrestricted:Tendcsnameusepackagegitver
usepackagehyperxmp
usepackagehyperref


% this commented paragraph is conceptual & needs fixing through a solution from this forum
% hypersetup%
% pdfversionid = detect if gitver has been loaded & set to gitVer if so; otherwise set to empty 
% %

begindocument
Hello world!

% The following again describes my intended requirements in words
% detect if gitver has been loaded & print versionBox if so; otherwise print "gitver not loaded"

enddocument

Normally you would just use @ifpackageloaded, but the command is limited to the preamble. To use it in the document body you need ltx@ifpackageloaded from the ltxcmds package. Since the macro has an @ in the name, you need to wrap it in makeatletter and makeatother.

documentclassarticle
usepackageexpl3
usepackageltxcmds
%csname sys_if_shell_unrestricted:Tendcsnameusepackagegitver
usepackagehyperxmp
usepackagehyperref

makeatletter
% this commented paragraph is conceptual & needs fixing through a solution from this forum
@ifpackageloadedgitver
 hypersetuppdfversionid = gitVer

 hypersetuppdfversionid = 

makeatother

begindocument
Hello world!

meaninggitVer
% The following again describes my intended requirements in words
% detect if gitver has been loaded & print versionBox if so; otherwise print "gitver not loaded"
makeatletter
ltx@ifpackageloadedgitverversionBoxgitver not loaded
makeatother

enddocument

Assuming that gitVer and VersionBox are defined by gitver, just add

providecommandgitVer
providecommandVersionBox[1]gitver not loaded

after the conditional loading.

This exploits the fact that providecommand does nothing if the command is already defined.