Dependent Package Requirement

jandrew has asked for the wisdom of the Perl Monks concerning the following question:

I have a package that depends on Archive::Zip and for most cases that seems to work. For netbsd and a few other cases though it doesn't work. I would like to provide alternate support unzipping files with Corions newish module Archive::SevenZip. I know how to test for either in the package and use the one that is loaded. I also know how to set up testing that will test either case. I just don't know/remember how to set up the dependencies for Makefile.PL and META.yml. I would like the package to build and test if either Archive::Zip or Archive::SevenZip will build/install but not require both.

I would especially like to accomplish this with Dist::Zilla if possible. Any help is greatly appreciated.

Update: I realized I didn't say this explicitly but I do want the prerequisites to fail if neither Archive::Zip or Archive::SevenZip will build successfully.

Comment on Dependent Package Requirement

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Re: Dependent Package Requirement by RonW (Parson) on May 19, 2016 at 19:29 UTC
If I understand you correctly, you want to package your module in a way that an attempt to install it won't also automatically cause either Archive::Zip or Archive::SevenZip to be installed, unless neither is already installed. From looking at http://search.cpan.org/~dagolden/CPAN-Meta-2.150005/lib/CPAN/Meta/Spec.pm, I think the best you can do is make both optional ("recomends"), then have a test to make sure one of those is available. You might be able to add code to Makefile.PL before the line with `WriteMakefile`, but I don't know how you could then get either archiver installed from there. Maybe you could do `system 'cpan Archive::Zip';` Update: Looked again and found 1140942. Seems it is possible to modify MakeFile.PL to munge the prereqs.	[reply] [d/l] [select]
Re^2: Dependent Package Requirement by jandrew (Chaplain) on May 19, 2016 at 21:00 UTC
RonW++ Thanks for replying. You have it right. Mostly I wouldn't ask but I know that at least one platform and several perl configurations fail to install Archive::Zip even though for now it is the preferred module to implement. The conundrum is how to succeed in the face of an imperfect module dependency. I was afraid that might be the answer. I'm planning on running some tests in a branch and see what I can get to happen in Travis-CI but I'm afraid it might take a hack on the cpan or cpanm apps to accomplish what I want. I will post to this thread as I have results but I have to get the test suite and module ready first so it will take several days before I know what won't work for sure.	[reply]
Re^3: Dependent Package Requirement by RonW (Parson) on May 19, 2016 at 21:27 UTC
After looking some more, I found 1140942. Looks like you could add more prereqs. See stevieb's sample MakeFile.PL in that post. Depending on the return value of `WriteMakefile`, you might even be able to try Archive:Zip first, then Archive::SevenZip	[reply] [d/l]
Re^4: Dependent Package Requirement by jandrew (Chaplain) on May 19, 2016 at 22:42 UTC
Re: Dependent Package Requirement by Anonymous Monk on May 18, 2016 at 22:46 UTC
WriteMakefile() is a function that takes args :)	[reply]


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