Hi, Zeno!
The loss of anonymous method style function calling is a known wart
with NiceSlice, unfortunately. It is a language design issue -- Perl
leaves very few of the "convenient" constructions unused. Since (as
you noticed) the &$ref(@params) syntax is preserved, it has not been a
major issue.
Source filters are indeed dangerous, but they remain the only way to
affect the syntax of the language itself until Perl 6 becomes
commonplace. NiceSlice has been rather thoroughly tested, and I use
it in essentially all my PDL code. (Now that I think of it, the C
preprocessor is a source filter too...) There are three warts to the
source preprocessing that I know of:
* Function refs: <<$ref->(@params);>> is overloaded with niceslicing
syntax; use "&$ref(@params)" [which you pointed out]
* String interpolation: <<print "$a (comment)";>> gets erroneously
turned into <<print "$a->nslice(comment)", so you have to break up the
quoted string. This has to do with the difficulty of parsing out the
Perl quoting structure, which can potentially be fixed -- but nobody
has yet felt moved to do so.
* Inline functions: if you use Inline::C or Inline::PP, you must say
"no PDL::NiceSlice" before the Inline call, else your foreign-language
code will get mangled.
On May 26, 2011, at 4:21 AM, Zeno Gantner wrote:
Hi all,
I am still new to PDL, and trying to get more comfortable with it.
So please excuse if my question is somehow naive ...
I found out that PDL::NiceSlice breaks calling function references.
Is this a known bug?
--
#!/usr/bin/perl
use 5.10.1;
use PDL::NiceSlice;
my $fun_ref = sub { say $_[0]; };
&$fun_ref('Hey!'); # works
$fun_ref->('Hey!'); # does not work
--
... gives the output:
--
Hey!
Can't call method "nslice" on unblessed reference at ./pdl-
niceslice.pl line 8.
--
By the way, PDL::NiceSlice is implemented as a Perl source filter,
what can be a bit dangerous.
What are the general recommendations towards PDL::NiceSlice? Is its
usage encouraged?
Best regards,
Zeno
--
MyMediaLite Recommender System Library: http://ismll.de/mymedialite
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