On Wed, 2002-09-04 at 14:38, Jonathan Scott Duff wrote:
> my $x;
> / (\S*) { let $x = .pos } \s* foo /
>
> After this pattern, $x will be set to the ending position of
> $1--but only if the pattern succeeds. If it fails, $x is
> restored to undef when the closure is backtracked
>
> I don't see any binding there, just letting.
I think the confusion here is that "let" is creating a binding, but the
binding is between the named variable (e.g. C<$x>) and the storage in
the result object (e.g. C<$0.{x}>). What C<$0.{x}> is is kind of beside
the point. It may be a binding as in:
... {let $x := $1} ...
or a stand-alone value as in:
... {let $x = $1 + 100} ...
Does this make sense? As I understand it, the let statement is
translated to something like this:
... { $self.{x} = sub {$1 + 100}; $x := $self.{x} } ...
Which will then be evaluated and the result substituted:
$0.{x} = $0.{x}.();
once backtracking is complete to avoid evaluating C<$1 + 100> before a
final understanding of what C<$1> contains is reached.
Is that roughly correct?
