Re^7: help with "symbol lookup error" message

> and keeping your modules (say) in a cpanfile so you can reinstall them quickly whenever you move to a new version.

This is the first time I've heard the term cpanfile, so I read this page:
https://metacpan.org/dist/Module-CPANfile/view/lib/cpanfile.pod

and it seems I could just maintain this file by having a requires $module line for each module I want to maintain. Then when a new version of perl is installed, I can just create a new directory, copy the cpanfile, and then run cpanm to reinstall all modules in that local directory using the new version of perl. Is that correct?

If I do that, is a record created anywhere in that directory indicating what version of perl was used to do the installation, or do I need to maintain that myself via directory naming conventions and/or README files?

Also does a new directory need to be created for each version of perl no matter how minor the update? For example, if I am currently using 5.36 and a 5.36.1 is released, do I need to reinstall all modules using 5.36.1 or can I wait for a larger update, e.g. 5.37?

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Re^8: help with "symbol lookup error" message by Corion (Patriarch) on Feb 03, 2023 at 21:36 UTC
Yes, that's the idea. I recommend installing all modules with `cpanm` and its `-L` option to install everything specific for an application in a separate directory. Usually, Perl guarantees (resp. takes great care) that you can upgrade between minor versions without recompiling provided that the new version of Perl was compiled exactly as the previous version. I'm not sure whether you can actually do that. I would simply reinstall, as that is usually easier.	[reply] [d/l] [select]
Re^9: help with "symbol lookup error" message by Special_K (Monk) on Feb 03, 2023 at 22:04 UTC
> Usually, Perl guarantees (resp. takes great care) that you can upgrade between minor versions without recompiling provided that the new version of Perl was compiled exactly as the previous version. I'm not sure I follow this. When you say "recompiling", do you mean recompiling the modules? Also how would one know that the new version of Perl was compiled exactly the same as the previous version? As you said, it's probably easier to just reinstall the modules. Also in a directory where perl modules are installed locally, is a record created anywhere in that directory indicating what version of perl was used to do the installation, or do I need to maintain that myself via directory naming conventions and/or README files?	[reply]
Re^10: help with "symbol lookup error" message by Corion (Patriarch) on Feb 03, 2023 at 22:24 UTC
Yes, you need to know the exact compilation configuration of your old Perl version. `perl -V` usually outputs most of what is needed, but there may be differences in how your C compiler (now) creates code. There is no way to determine what Perl version a module was compiled for after the fact. I suggest naming the directory `extlib-5.26.0` (or whatever) to keep track of things. Most likely you want to read the Coexistence with earlier versions of Perl section of the installation documentation of Perl.	[reply] [d/l] [select]


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