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=head1 TITLE
Built-in functions should be functions
=head1 VERSION
Maintainer: Johan Vromans <[EMAIL PROTECTED]>
Date: 27 Aug 2000
Last Modified: 20 Sep 2000
Mailing List: [EMAIL PROTECTED]
Number: 168
Version: 3
Status: Frozen
=head1 NOTE
See CHANGES for warp-up info.
=head1 ABSTRACT
RFC 26 proposes to eliminate the distinction between functions and
operators from a language perspective.
This RFC proposes that all Perl built-in functions should be usable in
all ways normal functions can be used. It is part of a big consipracy
to remove the number of cases with exceptional behaviour in Perl.
=head1 DESCRIPTION
Named operators, like C<abs>, can be called like functions in which
case they behave like functions. However, that's where the similarity
ends. You cannot override most builtins, and cannot tack a reference
to them.
There is no reason why the built-ins should be treated differently. A
famous Perl saying reads "if it looks like a function, it B<is> a
function." So be it.
In particular, it is desired that every built-in
=over 4
=item *
can be overridden by a user defined subroutine;
=item *
can have a reference taken;
=item *
has a useful prototype.
=back
=head2 Overriding
The principle of least surprise dictates that
sub I<foo> { return 10 }
print I<foo>();
should call I<foo>() and print "10" for all I<foo>.
Currently, most built-ins are excluded from this. For example:
sub system { return 10 }
print system();
Instead of calling the user defined system(), the built-in is used.
The second line may give a warning, but only if warnings are enabled:
Ambiguous call resolved as CORE::system(), qualify as such or use &
=head2 References
You can call a built-in, but not take a reference.
$a = \&system;
print $a->(-1)
This gives an error:
Undefined subroutine &main::system called
This should return a reference to the built-in instead.
Since C<&>I<foo> implicitly refers to the current package, it would be
acceptible to require
$a = \&CORE::system;
Note that this currently (5.7.0 DEVEL6806) results in the error:
Undefined subroutine &CORE::system called
which is surprising, if not misleading.
=head2 Prototypes
Currently, several built-ins do not provide prototype information.
prototype("CORE::abs") ==> ;$
prototype("CORE::shift") ==> undef
This must be fixed. One might even call this a bug, although the
current prototype mechanism is not powerful enough to cope with all
built-ins.
=head1 CHANGES
=head2 Version 3
Added CHANGES.
=head2 Version 3, 20 September
Frozen after some discussions on the mailing list. People seem to like
the idea, but worry about the prototypes. Other RFC will deal with that.
=head2 Version 2, 28 Aug 2000
Add Status indicator.
=head1 REFERENCES
RFC 26: Named operators versus functions
Tom Christiansen in <12231.967154045@chthon> (perl6-internals, Aug 24, 2000).
