CODEWITHSUNDEEP
c++namespaces
Mr. Boy
Mr. Boy

Reputation: 63846

Can you forward-declare a namespace alias in C++?

I'd like to set up some common aliases in a shared header, so that individual headers don't have to declare it individually. But I don't want to include the headers for the target namespace in this shared header, only declare the alias. Is this possible?

e.g I want namespace GE = Graphics::Engine; without including any graphics-engine headers.

Upvotes: 2

Views: 407

Answers (3)

David Rodríguez - dribeas
David Rodríguez - dribeas

Reputation: 208476

I would recommend against it. It can be done and it is simple enough, but what you are effectively doing is forcing your choice of aliases on all users of your headers.

Say that you build a component using this technique and General Electric buys the software, suddenly they get an arbitrary collision of namespaces. You are creating a conflict for no particular reason. Choose a namespace scheme that is simple to use and as unique as possible and then follow it. Adding shortcuts only complicates code (what's the difference between GE::type and Graphics::Engine::type?)

Upvotes: 2

Xeo
Xeo

Reputation: 131907

Since namespaces are open after being declared, just... declare them up-front:

namespace Graphics{ namespace Engine{} }
namespace GE = Graphics::Engine;

Upvotes: 8

R. Martinho Fernandes
R. Martinho Fernandes

Reputation: 234674

You can if you declare the namespaces beforehand:

namespace Graphics {
    namespace Engine {}
}
namespace GE = Graphics::Engine;

Upvotes: 8

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