Re: join() and split() to respect string overload operations

On Mon, Jun 07, 2010 at 01:46:00PM +0200, Abigail wrote:
> I don't consider 'substr' to be the inverse of '.'. In particular, it
> doesn't work the other way around. If substr() is overloadable, then
> 
>     substr $str, $pos, $len, $repl;
> 
> is overloaded as well. How do I reserve that with '.'?

  do { my $new = $str; substr $new, len $str, 0, $repl; $new } 
    eq $str . $repl

> It's not that I oppose 'substr' to be overloadable - I just don't find
> the "reversability" a very compelling argument. There are other overloadable
> operations that aren't reverable: abs, int, bool, "", 0+, qr, x, x=, <>, -X,
> ~~, ${} and friends.

Oh, sure. Some of these operators destroy information and cannot be
inverted.


OK, so lets ignore the mathematical argument of invertable operations,
and go for a much more practical appeal: I would like CORE::substr(),
CORE::split(), and optionally m// and s///, to operate on string-like
objects.

It would be great if

  my $message = String::Tagged->( "Hello, world" );
  $message->apply_tag( 0, 12, b => 1 );

  my $who = ( split ' ', $message )[1];

Would return a String::Tagged object, retaining that tag within it.

Ideally I'd love to be able to, say,

  $message =~ s{(\d+)}
               {String::Tagged->new($1)->apply_tag(0,len $1,fg=>'red'}eg;

To highlight all the numbers in a string in red; but that's largely an
extension exercise.

Simply having CORE::substr() overloadable would be an excellent start on
that.

-- 
Paul "LeoNerd" Evans

[email protected]
ICQ# 4135350       |  Registered Linux# 179460
http://www.leonerd.org.uk/

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