Extending and/or parametric object as attribute

Question

As I understand now from Array as object I have to use parametric object, because using non-parametric Logtalk objects implies that I have to use assert i.e. any change/set rewrites the whole array.

The problem is then :

how do you EXTEND the Array class..
OR instantiate it as ATTRIBUTE in the host class

Point 1

:- object(a2d, instantiates(array)).

:- end_object.

```
Reference to unknown object: array
```

even if it works, how do u access it internally .

Point2

means modifying the Term somehow ?

score 1 · Accepted Answer · edited Apr 19 '22 at 00:15

1

In that parametric object solution, the object is used to encapsulate the predicates working on the array representation and object parameter is used to hold the (compound) term representing an array itself.

The parametric object, a prototype in this case, can be extended as any other prototype:

:- object(a2d(_Array_), extends(array(_Array_)).

:- end_object.

Note that the identifier of the parametric object is array(_) (i.e. a compound term). Thus, array(_) and array are identifiers for different objects.

edited Apr 19 '22 at 00:15

sten

7,028
9
41
63

answered Apr 18 '22 at 10:56

Paulo Moura

18,373
3
23
33

Domain error: value array(A) is not in domain class – sten Apr 18 '22 at 21:41
1

Sorry. Copy and paste error. Fixed now. – Paulo Moura Apr 18 '22 at 22:21
bummer ;) ..... – sten Apr 18 '22 at 22:59
Array ==> _Array_ – sten Apr 19 '22 at 00:07
1

Note that you only need to write an object parameter using the syntax `_ParameterName_` when you want to access it as illustrated in the other linked answer (there are other ways to access object parameters). I.e. your `Array` to `_Array_` edit of my answer is only advised iff in the `a2d` object you're adding predicates (or directives) that refer to the parameter. – Paulo Moura Apr 19 '22 at 09:04
yes i do..plus i override get/set – sten Apr 20 '22 at 00:32

Extending and/or parametric object as attribute

1 Answers1