in reply to slurping __DATA__
do is "not really a function". It is a block that
has a seperate scope from wherever it was called from. This
allows you to localize $/ so that when execution
leaves our "temporary" scope, $/ will be what it
was before it was changed.
If you look up $/ in perlvar, you will see
You may set it to a multi-character string to match a multi-character terminator, or to "undef" to read through the end of file.Finally, <DATA> returns the next line from the filehandle DATA, and since $/ is undefined, the entire contents of the file are returned and "caught" in a scalar. UPDATE: i should add that this is one of those few cases where local is a good choice. For example,
Is essentially the same aslocal $/;
Which is not the same aslocal $/ = undef;
Even though that last snippet will be contained inside a do block ... $/ will still be undef afterwards. Try this - make two files foo.txt and bar.txt and run this:$/ = undef;
Then go back and add local to the do block.# print entire file open FH,'foo.txt'; my $foo = do {$/ = undef;<FH>}; print $foo; # print only first line open FH,'bar.txt'; my $bar = <FH>; print $bar;
jeffa
L-LL-L--L-LL-L--L-LL-L-- -R--R-RR-R--R-RR-R--R-RR B--B--B--B--B--B--B--B-- H---H---H---H---H---H--- (the triplet paradiddle with high-hat)
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