jstraitlets.py 文件源码

def validate(self, obj, value):
        if self.allow_undefined and value is undefined:
            return value

        # Should validate against only one of the trait types
        valid_count = 0
        with obj.cross_validation_lock:
            for trait_type in self.trait_types:
                try:
                    v = trait_type._validate(obj, value)
                except T.TraitError:
                    continue
                valid_count += 1
            if valid_count == 1:
                # In the case of an element trait, the name is None
                if self.name is not None:
                    setattr(obj, '_' + self.name + '_metadata',
                            trait_type.metadata)
                return v
        self.error(obj, value)