Implementing NSMutableCopying automatically

With our ability to generate both NSCopying conformance and the Mutable counterpart of objects, it is possible to generate an NSMutableCopying counterpart automatically. NSMutableCopying is a convenience method that returns an instance of an object known to have mutable members.

Create your stencil as follows:

{% for type in types.implementing.AutoMutableCopy %}
extension {{ type.name }}: NSMutableCopying {
    func mutableCopy(with zone: NSZone? = nil) -> Any {
        return Mutable{{type.name}}(
        {% map type.variables into vars using var %}
            {{ var.name }}: {{ var.name }}{% endmap %}
        {{ vars|join:"," }})
    }
}
{% endfor %}

This stencil is very similar to the one used to generate the NSCopying protocol conformance.