using/typedef of namespace in header

Question

I have a use case for the std::placeholder in a test application but am wondering if, in an effort to make things look a little cleaner on an API side, there is a way to bend using, typedef or even #define to alias the namespace at the header level.

// .../datarequestprocessor.h
class DataRequestProcessor {
public:
    using ProcessFunction = std::function<void(const ResultData &)>;
    using RequestResultHandle = std::placeholders; // No go. Same with ::_1
    ...
};

// ../datarequestprocessor.cpp
ProcessFunction DataRequestProcessor::prepOne()
{
    auto func = std::bind( &DataModel::setData,
                           m_model,
                           RequestResultHandle::_1 );
    return func;
}
... // For other variations.

This is purely semantic and also just an effort to learn about the nature of the using keyword. More of a learning experience then a real world application proposition.

Cheers

Answer 1

If you want it at the header level, then it's a simple matter of introducing a namespace alias:

namespace RequestResultHandle = std::placeholders;

The above won't be accepted inside a class however.