Oh dear thats a while to wait! (I am on system perl 5.12.3)
Does anyone know if there is a perl file in the system tree I can go and
butcher to remove this 'feature' ? Does anyone know what the patch changed?
Karl
On 13/04/2012, at 2:40 AM, Derek Lamb wrote:
> According to Luis Mochan's recent message to the perldl list (March 8th
> 2012), this is fixed with Perl 5.15.8 and later. So between Perl 5.10.1 (or
> maybe .0) and 5.15.8 there's this problem (in the debugger only?).
>
> Derek
>
> On Apr 11, 2012, at 11:46 PM, Karl Glazebrook wrote:
>
>> Hi everyone
>>
>> I had some trusty old code start to behave weirdly in the latest PDL/perl
>>
>> Quite simple:
>>
>> $iy = which($wav0<2000);
>> $dmags($iy) .= 1;
>>
>>
>> "Can't return a temporary from lvalue subroutine"
>>
>> It seems I have fallen in to this issue described in PDL::Indexing
>>
>>> A nice feature in recent perl versions is lvalue subroutines (i.e.,
>>> versions 5.6.x and higher including all perls currently supported by PDL).
>>> That allows one to use the slicing syntax on both sides of the assignment:
>>>
>>> pdl> $im->slice(':,(2)') .= zeroes(5)->xvals->float
>>> Related to the lvalue sub assignment feature is a little trap for the
>>> unwary: recent perls introduced a "feature" which breaks PDL's use of
>>> lvalue subs for slice assignments when running under the perl debugger,
>>> perl -d. Under the debugger, the above usage gives an error like: Can't
>>> return a temporary from lvalue subroutine... So you must use syntax like
>>> this:
>>>
>>> pdl> ($pdl = $im->slice(':,(2)')) .= zeroes(5)->xvals->float
>>> which works both with and without the debugger but is arguably clumsy and
>>> awkward to read.
>>
>> What is this 'feature' and what idiot in the Perl community is responsible
>> for this? To have the same code work fine when run normally and then fail in
>> the debugger is scandalous!
>>
>> Is there some way to fix this globally? I see some traffic on the mailing
>> list from 2010 about this - I can't believe it is still there.
>>
>> Grr!
>>
>>
>> Karl
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> PDL-porters mailing list
>> [email protected]
>> http://mailman.jach.hawaii.edu/mailman/listinfo/pdl-porters
>>
>
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