PHP マニュアル: Casting

Type Componere\cast_by_ref(Type $type, $object)

An object of type Type, cast from object, where members are references to object members

警告

Shall throw InvalidArgumentException if the type of object is or is derived from an internal class

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Shall throw InvalidArgumentException if Type is an interface

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Shall throw InvalidArgumentException if Type is a trait

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Shall throw InvalidArgumentException if Type is an abstract

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Shall throw InvalidArgumentException if Type is not compatible with the type of object