Hi Jens,
Jens Luedicke [19/01/02 16:32 +0100]:
> I want to delete an element from an array
> using the following code:
>
> use Inline Ruby => <<CODE;
>
> def remove_from_array(array,elem)
> array.delete elem
> return array
> end
>
> CODE
>
> The code doesn't work like I want, because
> I get the following error:
>
> #<ArgumentError: wrong # of arguments(42 for 2)>
You have to make sure you call it like this:
$new_aref = remove_from_array($aref, $elem);
The reason you have to pass a *reference* is that Perl expands arrays in
parameter lists by default, meaning you sent every element of the array as a
separate argument. That's not cool with Ruby.
It returns a reference (not an array) because in Ruby, everything is a
reference. Inline::Ruby has some compile-time options about whether to
flatten arrays as they are returned. I haven't documented them because I
don't think you should do that.
That's the short answer. If you want the long one, read my PS, otherwise just
use this code:
----8<----
use Data::Dumper;
use Inline Ruby => <<CODE;
def remove_from_array(array, elem)
array.delete elem
return array
end
CODE
$aref = [qw(simon frank neil harry)];
$new_aref = remove_from_array($aref, "neil");
print Dumper $new_aref;
---->8----
Later,
Neil
PS: the compile-time options are defined in rb2pl.h:
o CHECK_CONTEXT
If defined, enables the following two definitions.
o FLATTEN_ARRAYS
If defined, then if a Ruby subroutine returns an array, and the subroutine
was called in "array context", then the array is flattened onto Perl's
return value stack.
NOTE: if this is enabled, you can't tell the difference between the two
return values for this function:
def return_element(a)
if a == "list"
return [0]
else
return 0
end
end
In the first case, the [0] is flattened onto Perl's stack, giving an array
with one element: @a = (0).
In the second case, the 0 is pushed onto Perl's stack, also giving an array
with one element: @a = (0).
By default, this IS NOT enabled.
o FLATTEN_CALLBACK_ARGS
If defined, then when a Perl iterator is called from Ruby, the argument
passed to it will be flattened onto the Perl call stack, if the type of the
Ruby argument is an array.
NOTE: if enabled, you can't tell the difference between being called from
'yield [3]' and 'yield 3', for similar reasons to the above argument for
return values.
By default, this IS enabled.
Currently the only way to set these options is to edit rb2pl.h before
building Inline::Ruby. It's very simple, and they are well-documented in the
header file.
