Thank you all for the helpful replies. This code did it for me:
eval {$subset=$data->slice($b)->copy };
if ($@) {
message "Wrong Slice string $@" ,mb::Error;
} else {
...
Ingo
On 08/21/2013 08:56 PM, David Mertens wrote:
> I'm not sure when a *bad* slice is caught, but an out-of-bounds slice
> is not caught until an actual evaluation. So, do a null operation,
> like adding zero in place. Note I use the eval { ... 1; } or do { ...
> }; idiom for exception handling, which I really like. It works just
> like a try/catch block, and is just as compact.
>
> my $slice;
> eval {
> $slice = $data->slice($string);
> $slice += 0;
> 1;
> } or do {
> croak("Bad slice string $string");
> };
>
> This conflates a malformed string and an out-of-bounds error, which
> may or may not be what you want. But hopefully it's a start.
>
> David
>
>
> On Wed, Aug 21, 2013 at 2:49 PM, Luis Mochan <[email protected]
> <mailto:[email protected]>> wrote:
>
> I believe you are missing quotes. The argument of eval is a string to
> be compiled and executed, as in
> eval ('$y=slice ($x,"0,8,,")')
> Regards,
> Luis
>
>
> On Wed, Aug 21, 2013 at 02:14:14PM +0000, Chris Marshall wrote:
> > I don't have a working PDL but I mean using
> > eval for exception trapping. Try looking at
> > the eval docs in perldoc -f eval or someone with
> > a working example....
> >
> > On Wed, Aug 21, 2013 at 1:51 PM, Ingo Schmid <[email protected]
> <mailto:[email protected]>> wrote:
> > > Chris,
> > >
> > > sorry, I get this. It never returns, just dies, apparently.
> > >
> > > pdl> help $x
> > > This variable is Double D [2,6,1,4] P 0.38KB
> > > pdl> eval (slice ($x,'0,8,,'))
> > >
> > >
> > > Runtime error: Stringizing problem: Slice cannot start or end
> above
> > > limit. eval {...} called at Basic/Core/Core.pm.PL
> <http://Core.pm.PL> (i.e. PDL::Core.pm)
> > > line 2969
> > > PDL::string('PDL=SCALAR(0x4e242b0)', undef, '') called at
> (eval 581)
> > > line 5
> > >
> > >
> > >
> > > On 08/21/2013 03:36 PM, Chris Marshall wrote:
> > >> eval ?
> > >>
> > >> On Wed, Aug 21, 2013 at 9:20 AM, Ingo Schmid <[email protected]
> <mailto:[email protected]>> wrote:
> > >>> Hi,
> > >>>
> > >>> I want a user to enter a string defining a slice of a piddle
> to extract.
> > >>>
> > >>> Now when I call
> > >>>
> > >>>
> > >>> $y=$x->slice($string) || barf "Not a valid slice\n";
> > >>>
> > >>> that does not catch it. How do I catch it?
> > >>>
> > >>> Ingo
> > >>>
> > >>> _______________________________________________
> > >>> Perldl mailing list
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> > >>>
> > >
> >
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> o
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