down_cast overloads

Synopses

Declared in <absl/base/casts.h>

Overload of down_cast for references. Use like this: absl::down_cast<T&>(foo). The code is slightly convoluted because we're still using the pointer form of dynamic cast. (The reference form throws an exception if it fails.)

template<
    typename To,
    typename From>
[[nodiscard]]
To
down_cast(From& f);

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An "upcast", i.e. a conversion from a pointer to an object to a pointer to a base subobject, always succeeds if the base is unambiguous and accessible, and so it's fine to use implicit_cast.

template<
    typename To,
    typename From>
[[nodiscard]]
To
down_cast(From* f);

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Return Value

  • f, downcast to To.

  • f, downcast to To, or null if f is null.

Note

The return value should not be discarded.

Parameters

Name

Description

f

The source reference to downcast.

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