Re: [Boost-users] Writing an inline nullary function object?

Subject: Re: [Boost-users] Writing an inline nullary function object?
From: Eric MALENFANT (Eric.Malenfant_at_[hidden])
Date: 2010-12-01 13:35:16

De : Robert Jones
> How can I write an inline nullary function object, returning a fixed
> value? The equivalent of this...
> 
> int x = 4;
> 
> int f( ) { return x; }
> 
> boost::function<int()> g = f;
> 
> but without defining the intermediate f()?
> 
> I thought this might work...
> 
> boost::function<int()> g = bind(bind(apply<int>(), _1 ), x );
> 

With Lambda, you could write:
        boost::function<int()> g = boost::lambda::constant(4);
or, if you want to refer to a variable, and have g() return the *current* value of that variable:
        int i = 4;
        boost::function<int()> g = boost::lambda::var(i);
        assert(g() == 4);
        i = 5;
        (assert(g() == 5);

I'm not aware of something equivalent for Bind, however.