任何gnosis . xml . validity类只能用符合xml方言有效性约束的参数进行实例化。

Any gnosis.xml.validity class can only be instantiated with arguments obeying XML dialect validity constraints.

youdao

您可以用其它编程语言创建类似的功能，但Python提供了非常通用的反射机制，而且能够清晰地表达有效性约束。

You could create an analogous capability in other programming languages, but Python provides particularly versatile reflection mechanisms, and allows clear expression of validity constraints.

youdao

这个表使用引用完整性约束确保数据的有效性。

This table USES referential integrity constraints to ensure data validity.

youdao