Re: Use of uninitialized value in substitution (s///)

Hugh Lawson <hlawson@xxxxxxxxxxxx> wrote in comp.lang.perl.misc:
> anno4000@xxxxxxxxxxxxxxxxxxxxxxx (Anno Siegel) writes:

[...]

> > > How can the code work right if $_ is undefined?
> >
> > Perl converts the undefined value to an empty string, if forced. It
> > does that here, finds that the empty string doesn't end with a "0" and
> > returns the empty string unchanged. That works perfectly well, but it
> > may not be what the programmer intended, hence the warning.
>
>
> Hello Anno,
>
> Thank you for the reply. Perhaps we are communicating at cross
> purposes. My point is that warning or not, the substitution seems to
> work as expected.

How is that surprising? The purpose of the substitution is to get rid
of a trailing null byte in C strings. If $_ is undefined, the
substitution returns an empty string. That doesn't have a trailing null
byte, so the purpose of the substitution is attained.

> To see what I'm talking about, search for this line
>
> $db->filter_fetch_value(
> sub { no warnings 'uninitialized' ;s/\0$// } ) ;
>
> in perldoc perldbmfilter.

I don't have perldbmfilter around (is it really spelled that way?).
The code is the same as earlier in the thread. What's to discover?

Anno
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