What does the reader of arrays and hashes return in scalar context?

[yuki-kimoto]

What does the reader of arrays and hashes return in scalar context?

6.2.3.2 :reader(optional_identifier)

https://github.com/Ovid/Cor/blob/master/rfc/attributes.md#6232-readeroptional_identifier

class MyClass {
  field @array : reader { (1, 2, 3) };
  field @hash : reader { (x => 1, y => 2) };
}

my $object = MyClass->new;

my $ret_array = $object->array;

my $ret_hash = $object->hash;

1. the first element of the array or the hash. In this case $ret_array is 1. $ret_hash is "x".
2. The count of the elements of the array or the hash. In this case $ret_array is 3. $ret_hash is 4.

[HaraldJoerg]

This will behave as Perl does if you use an array or hash in scalar context. A reader in scalar context returns the number of elements for an array field, and the number of keys (since Perl 5.26) for a hash field. So, $ret_array is 3 and $ret_hash is 2.

[Ovid]

At the present time, we don't plan to put attributes on fields which are not scalars because the behavior isn't clear. This would be a feature for after the MVP.

[yuki-kimoto]

Dose MVP contains the reader of the array and the hash?

[leonerd]

Readers on array/hash fields are already in Object::Pad. I'll put them in feature-class if the implementation of them is small and easy. I expect it will be small and easy. So quite likely.

[yuki-kimoto]

Thanks. OK, I will read Readers on array/hash fields in Object::Pad today.

[yuki-kimoto]

I red them now.

field @items :reader;
 
foreach my $item ( $obj->items ) { ... }   # iterates the list of items
 
my $count = $obj->items;                   # yields count of items

I assume this behavior in use feature 'class'.

[yuki-kimoto]

In my personal opinion, the word "spec" doesn't means the minimal implementation.

The people who implement the spec implements what the spec writes.

[leonerd]

@yuki-kimoto You do seem to be asking a lot of questions lately that could be quite easily answered by reading the spec / current implementation / inspiration from Object::Pad. Engagement is good, but perhaps you could do some of your own research first before raising all these questions?

[yuki-kimoto]

You do seem to be asking a lot of questions lately that could be quite easily answered by reading the spec / current implementation / inspiration from Object::Pad. Engagement is good, but perhaps you could do some of your own research first before raising all these questions?

It is possible to do it.

However, @haarg said

The class feature that LeoNerd is working on is intended to be the implementation of the Corinna spec.

#66

I can study Object::Pad, however, how do I know the difference between Corrina and Object::Pad?