Feature request: new $__ variable or a new operator: &&$
Hello!
I want to make do a nested hash structure, which seems like that:
my $pname = $self->{db}->{product}->offers->{ $product_id} ->
{name};
This kind of structures can be easily created by TableMap.
Problem: If any of the hash keys are undef, then perl "die"-ing with
an error: Cannot use undef as a HASH reference...
I suggest two kind of solution in the new (perl6) language, because
I think perl5 don't have good solution for that:
1, $__ variable, which is the result of the last operation, e.g:
my $pname = $self->{db} && $__->{product} && $__->offers && $__->{
$product_id } && $__->{name}
2, &&$ operator, which can be used like that:
my $pname = $self->{db &&$ ->{product} &&$ ->offers &&$ -> {
$product_id } &&$ ->{name};
I suggest the second, because it is more straightforward, but the
first is more flexible.
Regards,
dLux
--
Linux is like wigwam: no windows, no gates, apache inside!
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0 |
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dlux
8/2/2000 8:33:36 AM
perl.perl6.language
6835 articles. 
0 followers.
2 Replies
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dLux <dlux@kapu.hu> writes:
> Hello!
>
> I want to make do a nested hash structure, which seems like that:
>
> my $pname = $self->{db}->{product}->offers->{ $product_id} ->
> {name};
>
> This kind of structures can be easily created by TableMap.
>
> Problem: If any of the hash keys are undef, then perl "die"-ing with
> an error: Cannot use undef as a HASH reference...
>
> I suggest two kind of solution in the new (perl6) language, because
> I think perl5 don't have good solution for that:
>
> 1, $__ variable, which is the result of the last operation, e.g:
>
> my $pname = $self->{db} && $__->{product} && $__->offers && $__->{
> $product_id } && $__->{name}
>
> 2, &&$ operator, which can be used like that:
>
> my $pname = $self->{db &&$ ->{product} &&$ ->offers &&$ -> {
> $product_id } &&$ ->{name};
>
> I suggest the second, because it is more straightforward, but the
> first is more flexible.
reduce {last unless defined $a; eval "\$a->$b"} $self,
qw/{db} {product} offers {$product_id} {name}/;
Hmm... that is a tad unwieldy. And we don't have reduce yet. And I'm
not entirely sure that last would work how you want it to...
--
Piers
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0 |
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pdcawley
8/2/2000 11:20:14 AM
/--- On Wed, Aug 02, 2000 at 12:20:14PM +0100, Piers Cawley wrote:
| > 1, $__ variable, which is the result of the last operation, e.g:
| > my $pname = $self->{db} && $__->{product} && $__->offers &&
| > $__->{
| > $product_id } && $__->{name}
| > 2, &&$ operator, which can be used like that:
| > my $pname = $self->{db &&$ ->{product} &&$ ->offers &&$ -> {
| > $product_id } &&$ ->{name};
| > I suggest the second, because it is more straightforward, but
| > the
| > first is more flexible.
|
| reduce {last unless defined $a; eval "\$a->$b"} $self,
| qw/{db} {product} offers {$product_id} {name}/;
|
| Hmm... that is a tad unwieldy. And we don't have reduce yet. And
| I'm
| not entirely sure that last would work how you want it to...
\---
Where I can find the "reduce" command? I understand how it works,
but this is *VERY* dirty.
The $pname=eval{ ... } block is much cleaner...
But what about the suggestion? Is it a good suggestion?
How will I make it formal?
dLux
--
perl -e 'print
$i=pack(c5,(41*2),sqrt(7056),(unpack(c,H)-2),oct(115),10);'
|
|
0 |
|
dlux
8/2/2000 2:41:12 PM
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