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# inheritance

This folder contains examples of public, protected, and private inheritance,
for both prototype-based and class-based hierarchies.

This example defines a category named `predicates` which specifies three 
predicates, one public, one protected, and one private. This category is 
imported by the root objects: `parent` for the prototype hierarchy and 
`root` for the class hierarchy. Each root object have a set of three 
descendants, each one using one of the inheritance types.

The two object hierarchies are organized as follows:

```text
parent
	prototype1				% public inheritance
		descendant1
	prototype2				% protected inheritance
		descendant2
	prototype3				% private inheritance
		descendant3

root
	subclass1				% public inheritance
		instance1
	subclass2				% protected inheritance
		instance2
	subclass3				% private inheritance
		instance3
```

A second category named `interface`, imported by all objects except the 
sub-class instances, allows us to query the objects about their interfaces.

Print Logtalk, Prolog backend, and kernel versions (if running as a notebook):

```logtalk
%versions
```

Start by loading the example:

```logtalk
logtalk_load(inheritance(loader)).
```

`parent` interface:

```logtalk
parent::interface.
```

<!--
public/0 - public
protected/0 - protected
private/0 - private

true.
-->

`prototype1` extends `public::parent`:

```logtalk
prototype1::interface.
```

<!--
public/0 - public
protected/0 - protected

true.
-->

`prototype2` extends `protected::parent`:

```logtalk
prototype2::interface.
```

<!--
public/0 - protected
protected/0 - protected

true.
-->

The `prototype3` prototype extends `private::parent`:

```logtalk
prototype3::interface.
```

<!--
public/0 - private
protected/0 - private

true.
-->

The `descendant1` prototype extends `public::prototype1`:

```logtalk
descendant1::interface.
```

<!--
public/0 - public
protected/0 - protected

true.
-->

The `descendant2` prototype extends `public::prototype2`:

```logtalk
descendant2::interface.
```

<!--
public/0 - protected
protected/0 - protected

true.
-->

The `descendant3` prototype extends `public::prototype3`

```logtalk
descendant3::interface.
```

<!--
true.
-->

Object (root of the inheritance graph) interface:

```logtalk
root::interface.
```

<!--
public/0 - public
protected/0 - protected
private/0 - private

true.
-->

`instance1` instantiates `subclass1` that specializes `public::root`:

```logtalk
instance1::interface.
```

<!--
protected/0 - protected
public/0 - public

true.
-->

`instance2` instantiates `subclass2` that specializes `protected::root`:

```logtalk
instance2::interface.
```

<!--
protected/0 - protected
public/0 - protected

true.
-->

`instance3` instantiates `subclass3` that specializes `private::root`:

```logtalk
instance3::interface.
```

<!--
true.
-->
