You should not use diagnostics in production as this requires the loading of a very large chunk of useless info. Use warnings triggers the warnings. Use diagnostics only *expands* those warnings, thus use diagnostics is useful only if you don't understand what the warnings generated by use warnings mean.

When you use diagnostics perl loads a large quantity of data each and every time you run the script. If there are no warnings this will never be used. As already noted if there are warnings this will only be useful if you don't understand the warnings. You can get the same info from perlman:lib:diagnostics. There is extensive discussion of this here Use strict warnings and diagnostics and Use strict warnings and diagnostics or die

It is also worth a look at use warnings vs. perl -w as use warnings is a perl 5.6+ feature so will not work on the still common 5.005 or earlier. As noted -w works on Win32 or any other system as Perl will look at the shebang regardless of whether the OS does.

cheers

tachyon

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