Editing Generic programming (section)

=====Constrained genericity=====

For the list class shown above, an actual generic parameter substituting for <code lang=Eiffel>G</code> can be any other available class. To constrain the set of classes from which valid actual generic parameters can be chosen, a ''generic constraint'' can be specified. In the declaration of class <code lang=Eiffel>SORTED_LIST</code> below, the generic constraint dictates that any valid actual generic parameter will be a class that inherits from class <code lang=Eiffel>COMPARABLE</code>. The generic constraint ensures that elements of a <code lang=Eiffel>SORTED_LIST</code> can in fact be sorted.

<syntaxhighlight lang="eiffel">
class
    SORTED_LIST [G -> COMPARABLE]
</syntaxhighlight>