The exact heuristics may be helpful in this meditation. Quoting from the perlop section on I/O Operators:
If what the angle brackets contain is a simple scalar variable (e.g., <$foo>), then that variable contains the name of the filehandle to input from, or its typeglob, or a reference to the same. For example: 
    $fh = \*STDIN;
    $line = <$fh>;

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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(). That's because $x is a simple scalar variable, but $hash{key} is not--it's a hash element.

One level of double-quote interpretation is done first, but you can't say <$foo> because that's an indirect filehandle as explained in the previous paragraph.

In reply to Re: C<while> magic also working with glob(): intentional or not? by Util
in thread C<while> magic also working with glob(): intentional or not? by blazar

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