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Re: FileHandle: undef vs close

by Crackers2 (Parson)
on Apr 30, 2009 at 18:03 UTC ( #761121=note: print w/ replies, xml ) Need Help??

in reply to FileHandle: undef vs close

They're not 100% identical, as the following code shows:

use warnings; use FileHandle; $fh = new FileHandle "file", "r"; if (defined $fh) { print <$fh>; undef $fh; # automatically closes the file } $fh2 = new FileHandle "file", "r"; if (defined $fh2) { print <$fh2>; close $fh2; # automatically closes the file } print <$fh>; print <$fh2>;
Use of uninitialized value in <HANDLE> at t line 16. readline() on unopened filehandle at t line 16. readline() on closed filehandle GEN1 at t line 17.

Doing a close seems to maintain some information about the filehandle, and the variable stays defined. Doing an undef unsurprisingly undefs the variable, so you get a slightly different warning, and an extra one about it being udnefined.

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