angle operator behavior with filehandles in @_

From: John Bullock (john.bullock_at_stanford.edu)
Date: 08/29/04 

Date: Sat, 28 Aug 2004 22:35:56 -0700

Hello,

        I am puzzled by the behavior of the angle
operator (<>) when it operates on a filehandle
that is passed to a subroutine.

        Given filehandle FH, these lines are equivalent:

                my $tst1 = <FH>;
                my $tst1 = readline(FH);

        But if I set up a subroutine, there is an oddity:

                do_something(*FH);
                sub do_something {
                        my $tst1;
                        $tst = $readline($_[0]); # works
                        $tst1 = <$_[0]>; # doesn't work
                        $tst1 = < {$_[0]} >; # doesn't work
                }

Of course, I can get around this by storing the filehandle
in a scalar that I define in the subroutine. But I want to
understand why neither of the last two lines here works
as intended. (They just leave $tst1 undefined, provided
that it hasn't already been defined.) I've looked to what
I thought were the salient parts of the camel book, but I
had no luck. Can you enlighten me or point me to some
relevant reading?

Thanks,
--John

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