doesn't attempt to control the warnings will work unchanged.
All warnings are enabled in a block by either of these:
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+
use warnings ;
use warnings 'all' ;
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+
Similarly all warnings are disabled in a block by either of these:
no warnings ;
details of how this flag interacts with lexical warnings.
=item B<-W>
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+
If the B<-W> flag is used on the command line, it will enable all warnings
throughout the program regardless of whether warnings were disabled
locally using C<no warnings> or C<$^W =0>. This includes all files that get
to control warning behavior will still work as is.
=item 3.
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Apart from now being a boolean, the C<$^W> variable operates in exactly
the same horrible uncontrolled global way, except that it cannot
disable/enable default warnings.
=item 4.
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If a piece of code is under the control of the C<warnings> pragma,
both the C<$^W> variable and the B<-w> flag will be ignored for the
scope of the lexical warning.
=item 5.
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The only way to override a lexical warnings setting is with the B<-W>
or B<-X> command line flags.
code (using a C<local $^W=0>) if it really wants to, but not vice-versa.
=head2 Category Hierarchy
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+
A hierarchy of "categories" have been defined to allow groups of warnings
to be enabled/disabled in isolation.
L<perldiag>.
=head2 Fatal Warnings
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The presence of the word "FATAL" in the category list will escalate any
warnings detected from the categories specified in the lexical scope
into fatal errors. In the code below, there are 3 places where a
use warnings ;
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+
$a = 1 if $a EQ $b ;
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{
use warnings FATAL => qw(deprecated) ;
$a = 1 if $a EQ $b ;
}
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+
$a = 1 if $a EQ $b ;
=head2 Reporting Warnings from a Module
warning message.
=head1 TODO
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perl5db.pl
The debugger saves and restores C<$^W> at runtime. I haven't checked
whether the debugger will still work with the lexical warnings
=head1 SEE ALSO
L<warnings>, L<perldiag>.
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=head1 AUTHOR
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Paul Marquess