Default template parameters for policy based design

[Arkaitz Jimenez]

Hi all,
Working with the default parameters of a template class:

template <class policy1=defaultPolicy> myClass{}
I'd like as a lib user to be able to instantiate it without lt and gt
symbols <> or with them if a policy change is required.
Say:
//Default
myClass obj;
//Non-DefaultPolicy
myClass<Non-DefaultPolicy> obj;

I don't know if possible but maybe using typedefs is it possible to go
for a second typename that I can instantiate that way.
Currently it is this way:
//Default
myClass<> obj; // Note the "<>"
//Non-DefaultPolicy
myClass<Non-DefaultPolicy> obj;

Thanks

Arkaitz

 

[Victor Bazarov]

Working with the default parameters of a template class:

template <class policy1=defaultPolicy> myClass{}
I'd like as a lib user to be able to instantiate it without lt and gt
symbols <> or with them if a policy change is required.
Say:
//Default
myClass obj;
//Non-DefaultPolicy
myClass<Non-DefaultPolicy> obj;

I don't know if possible but maybe using typedefs is it possible to go
for a second typename that I can instantiate that way.

AFAIK, not possible. A template-name has to be followed by the angle
brackets if you want to instantiate that template. And you can't
declare a typedef that has the same name as a template, IIRC.

Currently it is this way:
//Default
myClass<> obj; // Note the "<>"
//Non-DefaultPolicy
myClass<Non-DefaultPolicy> obj;

Yes, what's so bad about the "<>" after the template with the default
argument?

V

 

[Arkaitz Jimenez]

Yes, what's so bad about the "<>" after the template with the default
argument?

V

Not that it is inherently bad, but wanted to "hide" the reality of
using a template until the user of the lib is aware of the available
policies and the rest of the puzzle.

Thanks

Arkaitz