This approach to modifying the symbol-table after a first call is roughly the technique that we used when we implemented a deprecated module: use deprecated; 
package OldeCrufte;
use deprecated qw(do_hack);  # calling OldeCrufte::do_hack() will carp

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package OldeCrufte;
use deprecated;              # using the OldeCrufte module will carp

[download]

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

In reply to Re: Is modifying the symbol table to redefine subroutines evil? by halley
in thread Is modifying the symbol table to redefine subroutines evil? by tlm

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