I have two versions of a set of scripts (a development version and a production version) running in the same cgi directory. The naming convention is: 
MainProg.pl
LayerA.pm
LayerB.pm
LayerC.pm
MainProg2.pl
LayerA2.pm
LayerB2.pm
LayerC2.pm

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Each file (except the bottom ones) contains a 'use LayerX.pm' (or whatever) line near the top. The development files of course each say 'use LayerX2.pm'.

When I shift the development version of a file or two over to the production set, I just drop the '2' from the file name and adjust the 'use ...' line. This works fine. But it's a nuisance and occasionally I flub it.

So I'd like to read the name of the current file, check for a '2' in the filename and then 'use ...' the appropriate next lower module.

'use' requires a bareword, so I can't say 'use LayerB$version'. What are the implications of: 

if ($version == 2) {
   use LayerB2;
}
else {
   use LayerB;
}

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Is there any downside to this? Seems like there are likely some compile-time vs. run-time issues.

Is there some other recommended method?

In reply to Conditional use of 'use' by dvergin

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