埃菲尔铁塔：比较类型的最佳方法而不会引起注意

Question

遇到了试图比较两种类型的Catcall，如何避免通过另一个非专用方法（例如字符串，class_id或类似的东西）呢？

SIT_UTIL

    class_name_lowercase (a_string: STRING): STRING
            -- a copy lowercased and pruned from preceding '!'
        do
            Result := a_string
            if Result.index_of('!', 1) = 1 then
                Result := Result.substring (2, Result.count)
                Result.to_lower
            else
                Result := Result.as_lower
            end
        ensure
            instance_free: class
        end

CLIENT_CLASS

    relationship_from_secondary_type_equal (a_type: like relationships.item.secondary_type): detachable like relationships.item
            -- Returns first instance of found relationship secondary type which equals given one
        do
            across
                relationships as l_rel
            until
                Result /= Void
            loop
--              if attached (a_type / l_rel.item.secondary_type) then -- Don't want conformance but equality

--              if attached (a_type.is_equal (l_rel.item.secondary_type)) then -- tried but as is_equal needs a like Current => Catcall
--              if attached (a_type.equal (a_type, l_rel.item.secondary_type)) then -- Catcall because b signature is like a
                if {SIT_UTIL}.class_name_lowercase (a_type).is_equal({SIT_UTIL}.class_name_lowercase (l_rel.item.secondary_type)) then
                    Result := l_rel.item
                end
            end
            check
                not_found_relationship: Result /= Void
            end
        end

Answer 1

一致性属性是反对称的，即如果 A→B 和 B→A ，则 A = B 。因此，两种类型相等是彼此一致的：

python manage.py runserver

（尽管 a_type.conforms_to (l_rel.item.secondary_type) and l_rel.item.secondary_type.conforms_to (a_type) 比较对象的类型而不是对象本身，但是上面的表达式仍然可以，因为由于符合规则 A = B ，并且仅当 TYPE当 A 和 B 本身是类型时，[A] =类型[B] 。

如果连接了其中一种类型，而另一种是可分离的，则您可能仍希望将它们进行相等比较。在这种情况下，可以使用以下代码：

conforms_to

比较谓词忽略附加标记：

    is_conforming (a_type, l_rel.item.secondary_type) and
    is_conforming (l_rel.item.secondary_type, a_type)