Paul wrote:
> --- Rob Dixon <[EMAIL PROTECTED]> wrote:
> > Paul wrote:
> > > > do {
> > > > my $empty;
> > > > $empty ++;
> > > > };
> > >
> > > Also, the do() is superfluous here, isn't it?
> >
> > I was trying to show something that would return a value in
> > the same way as a subroutine block (so that I didn't need a
> > return statement in the same way as a subroutine doesn't).
> > I started out with a bare block, but realised that it needed
> > a 'do' to have a value, and therefore make it non-redundant
> > in context.
>
> Got it.
>
> my $x = { code, more code.... }
>
> doesn't work, because the braces are expecting to be an anonymous hash
> in that context, so they aren't a block.
>
> my $x = do { code };
>
> works, because do flips the context, expecting a block and returning a
> value.
I hadn't actually thought of it that way, but it's remarkably well
explained.
Well done.
> That way I can say
>
> my $fh = do { local $_ };
> open $fh, $file or die $!;
>
> for a cheap, quick, anonymous filehandle in a scalar. :)
> (note to the peanut gallery: henceforward I digress!)
Ah, now that's not quite right. The 'do' block will create a
local copy of $_, initialised to 'undef'. The end of the block
returns 'undef' as it is the last executed line, and $_ will
be restored from its saved value. The line is therefore the
same as:
my $fh = undef;
or just
my $fh;
and the entire code works as:
open my $fh, $file or die $!;
> I've definitely used that trick...but all in all, for that
> *particular* usage I recommend
>
> use FileHandle;
> my $fh = new FileHandle $file or die $!;
>
> which is much more readable to the uninitiated, and still only two
> lines of code. ;o]
If we're counting lines, I think mine wins!
Rob
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