change ni * protos

[Tom Christiansen <tchrist@chthon.perl.com>]

Could you please remind me why you intentionally broke

    use strict;
    sub fn(*) { my $fh = shift;  print $fh "Boo!\n" }
    *SNEAK = *STDOUT;
    fn(SNEAK);

In _54, this was fine, because the prototype caused the function
to receive *SNEAK instead of 'SNEAK' as an argument.  Now, it just
gets a bareword string, which seems to defeat the purpose of the
prototype.  Typeglob protos used to be documented as follows (in
Camel II):

    And a * does whatever it has to do to turn the argument into a
    reference to a symbol table entry.  It's typically used for
    filehandles.

But they are now documented in perlsub(1) like this:

    A * allows the subroutine to accept a bareword, constant, scalar
    expression, typeglob, or a reference to a typeglob in that slot.
    The value will be available to the subroutine either as a simple
    scalar, or (in the latter two cases) as a reference to the
    typeglob.

I don't understand the win.  Now every function that hopes to use
this a filehandle passed in has to pull in Symbol::qualify_to_ref(),
or do the equivalent work.  That means the function that used to
say

    my $fh = shift;

must now say:

    use Symbol;
    my $fh = Symbol::qualify_to_ref(shift, caller);

There are other subtle problems, too.  If you don't lock it in right
away, you're doomed.  You can't do anything useful with that value,
like storing it into a data structure or passing it to another
function, without doing the Symbol::qualify_to_ref() thing on the
value first.  You'd lose the critical caller info otherwise.  This 
was never a concern when you had a real typeglob, and now it is.

It's bad enough that it breaks old code; in fact, this is *not* in
the release notes as a code-breaking incompatibility, but needs to
be!  Perhaps worse still, I can't see how this is an advantage.  It
also to my eye causes a lot more work than we ever had to go through
before.  What is the purpose?  I don't understand.  I'm sure you
had a good reason, but I am not seeing it.

Thank you,

--tom

#########################
# This file:
#########################

    use strict;

    $|=1; 

    package Fab;

    sub ululation(*) { 
	my $fh = shift;
	print $fh "this went out $fh\n"
	    or warn "failed to print to fh $fh: $!\n";

    } 

    package main;

    print "testing *STDOUT...."; Fab::ululation(*STDOUT);
    print "testing *stdout...."; Fab::ululation(*stdout);

    print "testing *STDOUT{IO}...."; Fab::ululation(*STDOUT{IO});
    print "testing *stdout{IO}...."; Fab::ululation(*stdout{IO});

    print "testing STDOUT...."; Fab::ululation(STDOUT);
    print "testing stdout...."; Fab::ululation(stdout);

    print "testing *snigglebottom...."; Fab::ululation(*snigglebottom);
    print "testing *snigglebottom{IO}...."; Fab::ululation(*snigglebottom{IO});
    print "testing snigglebottom...."; Fab::ululation(snigglebottom);

    __END__

#########################
# Produced this in _54:
#########################

testing *STDOUT....this went out GLOB(0x8dc18)
testing *stdout....this went out GLOB(0x8dc3c)
testing *STDOUT{IO}....this went out GLOB(0x8d054)
testing *stdout{IO}....this went out GLOB(0x8d054)
testing STDOUT....this went out GLOB(0x8dc18)
testing stdout....this went out GLOB(0x8dc3c)
testing *snigglebottom....failed to print to fh GLOB(0x9b4b4): Bad file descriptor
testing *snigglebottom{IO}....Can't use an undefined value as a symbol reference at /tmp/globtest line 26.


############################
# But produced this in _63:
############################

testing *STDOUT....this went out GLOB(0xa5490)
testing *stdout....this went out GLOB(0xa54b4)
testing *STDOUT{IO}....this went out IO::Handle=IO(0xa54a8)
testing *stdout{IO}....this went out IO::Handle=IO(0xa54a8)
testing STDOUT....Can't use string ("STDOUT") as a symbol ref while "strict refs" in use at /tmp/globtest line 9.

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Follow-Ups from:

Gurusamy Sarathy <gsar@ActiveState.com>

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