Passing Filehandles

• In The Beginning, filehandles weren't first-class values

• Consider code like this:

        open FH, ...;
        print FH ...;
        $z = <FH>;
        close FH;

• Here FH is actually a literal string (a 'bareword')

• Almost as if you had written something like this:

        open "FH", ...;
        print "FH" ...;    
        $z = <"FH">;
        close "FH";

• All Perl's I/O functions expect to get strings

  • They then resolve the string to a glob in the usual way

  • Then they extract the filehandle part of the glob

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Copyright © 2003 M. J. Dominus