I'm thinking of putting together a basic developer aid for my workplace, a pragmatic module called deprecated. The idea is to detect when a user is probably a developer, and caution the user that they're depending on a deprecated module or symbol.

(In our facility, we have many environment variables which could hint to a script that it's being executed by a developer, and not by a typical end-user. If you have other more general ideas to detect this situation, that's a side question.)

For a wholly-deprecated module, I would just add one line to the top of the module. Then when the top-level script is executed in a developer environment, deprecated::import() would simply carp about how OldeCruft is deprecated. The deprecation is just a warning; no changes are made to the rest of the behavior. 

package OldeCruft;
use deprecated; # carps if module loaded
...

[download]

However, I'd also like to be able to deprecate specific symbols within the crufty namespace, without editing anything else deep in OldeCruft.pm. For example, if OldeCruft::dangerous() is deprecated, then the script should carp about that fact on the FIRST call to that sub. 

package OldeCruft;
use deprecated qw(dangerous);
               # carps if OldeCruft::dangerous() is called
...

[download]

Is there a straightforward and robust way to hook each named deprecated sub with a separate check-and-carp behavior? I'm not too familiar with the way sub names are joined to a symbol hash, and want to know if manipulating that symbol hash is a risky or generally safe proposition.

Update: use deprecated; contains the tested and documented implementation, from Aristotle's suggestions.

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[ e d @ h a l l e y . c c ]

In reply to use deprecated; by halley

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