boost::openmethod::policies::std_rtti::fn::type_index :: Boost.OpenMethod

# boost::openmethod::policies::std_rtti::fn::type_index

Returns a key that uniquely identifies a class.

## Synopsis

Declared in `<boost/openmethod/policies/std_rtti.hpp>`

    static
    std::type_index
    type_index(type_id type);

## Description

C++ does not guarantee that there is a single instance of `std::type_info` per type. `std_rtti` uses the addresses of `std::type_index` objects as `type_id`s. Thus, the same class may have multiple corresponding `type_id`s. `std::type_index` objects, on the other hand, are guaranteed to compare as equal iff they correspond to the same class, and they can be used to identify the `type_id`s pertaining to the same class.

## Return Value

A `std::type_index` for `type` (cast to a `const std::type_info&`).

## Parameters

Name | Description
--- | ---
type | A `type_id`.

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