TWeakPtr::UE_REQUIRES (constrained conversion constructor)

function Core Since 5.0

#include "Templates/SharedPointer.h"

Access: public Specifiers: inline

Description

Constrained conversion constructor that copies a TWeakPtr<OtherType> into a TWeakPtr<ObjectType> only when OtherType* is convertible to ObjectType*. Enables type-safe derived-to-base weak pointer conversions.

Caveats & Gotchas

• The ESPMode template parameter (Mode) must match between source and destination — you cannot convert between a ThreadSafe and a NotThreadSafe TWeakPtr using this constructor.
• Like all weak pointer copies, this constructor only copies the weak reference count controller and the raw object pointer; it does not extend the object's lifetime or Pin() it.

Signature

template < typename OtherType UE_REQUIRES(std::is_convertible_v<OtherType*, ObjectType*>) > inline TWeakPtr( TWeakPtr< OtherType, Mode > const& InWeakPtr )

Parameters

Name	Type	Description	Default
InWeakPtr	TWeakPtr< OtherType, Mode > const&	Source weak pointer whose OtherType must be implicitly convertible to ObjectType.	—

Example

Storing a derived weak ptr as a base weak ptr C++

TSharedPtr<FMyDerivedClass> Derived = MakeShared<FMyDerivedClass>();
TWeakPtr<FMyDerivedClass> WeakDerived = Derived;
// Upcast to base via constrained constructor
TWeakPtr<FMyBaseClass> WeakBase = WeakDerived;
if (TSharedPtr<FMyBaseClass> Pinned = WeakBase.Pin())
{
    Pinned->DoWork();
}

Version History

Introduced in: 5.0

Version	Status	Notes
5.6	stable	—

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