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# carengines

For a description of this example, please see the comments in the
`carengines.lgt` source file.

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

```logtalk
%versions
```

Start by loading the example:

```logtalk
logtalk_load(carengines(loader)).
```

Both cars provide the same interface, declared in the protocol
that is implemented by the categories imported by each object.

Public predicates of the `sedan` object:

```logtalk
%%table
sedan::current_predicate(Predicate).
```

<!--
P = reference/1 ;
P = capacity/1 ;
P = cylinders/1 ;
P = horsepower_rpm/2 ;
P = bore_stroke/2 ;
P = fuel/1 ;
false.
-->

Public predicates of the `coupe` object:

```logtalk
%%table
coupe::current_predicate(Predicate).
```

<!--
P = reference/1 ;
P = capacity/1 ;
P = cylinders/1 ;
P = horsepower_rpm/2 ;
P = bore_stroke/2 ;
P = fuel/1 ;
false.
-->

The `sedan` engine properties are the ones defined in the corresponding 
imported category (`classic`):

```logtalk
sedan::(reference(Name), cylinders(Cylinders), horsepower_rpm(HP, RPM)).
```

<!--
Name = 'M180.940', Cylinders = 6, HP = 94, RPM = 4800.
-->

The `coupe` engine properties are the ones defined in the corresponding 
imported category (`sport`) plus the ones inherited from the top category 
(`classic`) that are not overridden:

```logtalk
coupe::(reference(Name), cylinders(Cylinders), horsepower_rpm(HP, RPM)).
```

<!--
Name = 'M180.941', Cylinders = 6, HP = 115, RPM = 3657.
-->
