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file - Why can't I use the diamond operator with an array in Perl?

Code

$ cat test1
hello 
i am 
lazer

nananana
$ cat 1.pl
use strict;
use warnings;

my @fh;
open $fh[0], '<', 'test1', or die $!;

my @res1 = <$fh[0]>;  # Way1: why does this not work as expected?
print @res1."
"; 

my $fh2 = $fh[0];
my @res2 = <$fh2>;    # Way2: this works!
print @res2."
";

Run

$ perl 1.pl
1
5
$

I am not sure why Way1 does not work as expected while Way2 does. Aren't those two methods the same? What is happening here?

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1 Answer

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by (71.8m points)

Because from perlop:

If what's within the angle brackets is neither a filehandle nor a simple scalar variable containing a filehandle name, typeglob, or typeglob reference, it is interpreted as a filename pattern to be globbed, and either a list of filenames or the next filename in the list is returned, depending on context. This distinction is determined on syntactic grounds alone. That means <$x> is always a readline() from an indirect handle, but <$hash{key}> is always a glob().

You can spell the <> operator as readline instead to avoid problems with this magic.


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