TITLE

Filehandles should use * as a type prefix if typeglobs are eliminated.

VERSION

  Maintainer: Peter Scott <peter@psdt.com>
  Date: 5 Aug 2000
  Mailing List: perl6-language@perl.org
  Number: 10
  Version: 3
  Status: Retracted

ABSTRACT

Version 1 of this RFC stated: "The lack of a type-defining punctuation character prefix for filehandles makes them second-class variables in Perl. If typeglobs are eliminated in Perl 6, the * character would become available as a type prefix character and could be used for filehandles."

Versions 2 and 3 withdraw this request, contingent upon the removal of bareword filehandles in Perl 6. If scalars or objects in scalars ($fh) are used for filehandles everywhere then there is no need to make a new type out of them. The rest of the original RFC is left below for archival purposes.

DESCRIPTION

To pass filehandles around one either has to use a typeglob (local *FH) or put them in a scalar (my $fh = new FileHandle or the 5.6 open $fh, ...), at which point you can't tell that they're filehandles without the right context.

There have been serious proposals to eliminate typeglobs in Perl 6. If they get axed, the * character could be reused for another datatype and the filehandle is fortuitously closely related.

The mental jump is fairly small, since most people other than module developers only ever saw * used for filehandles anyway:

     local *FH;
     open (FH, ...);

This proposal would change that to

     open (my *fh, ...);

IMPLEMENTATION

Backwards compatibility takes a hit unless the current filehandle syntax is grandfathered in; I am not taking a position on whether it should be. Since it is contingent upon typeglobs being eliminated, it won't break any existing code that already uses typeglobs that won't be broken anyway.

Use of readlines will now look like

     while (<*fh>) { ...

which means that the use of the angle operator for globbing also has to go. As if an excuse were needed.

This proposal also applies to directory handles.

REFERENCES