Ami Ganguli wrote:

Hi all,

I'm using an object as a placeholder, and would like to call various methods to the object from within my actions. Something along the lines of:

port = (s1= *digit) [ _placeholder->setPort( as<int>(s1) ) ];

I'm not exactly sure what _placeholder is here, or what you mean by "using an object as a placeholder".

I've found a way to do something equivalent using method pointers, but the resulting code is really opaque. I'm afraid nobody else will ever be able to figure out what I've done.

I also know I can do this by creating separate function objects for each method that will be called. This is less opaque, but really verbose. I end up with hundreds of lines of boilerplate code.

Is there a "right" way to achieve something similar?

I'm afraid not. But if you go the route of creating function object wrappers, then you can get a nice syntax at the call site: struct setPortFun { typedef X result_type; X operator()(Object & obj, int arg) const { return obj.setPort(arg); } }; xpr::function<setPortFun>::type setPort const = {{}}; port = (s1= *digit) [ xpr::ref(obj)->*setPort( as<int>(s1) ) ]; Xpressive recognizes this use of ->* and treats it as: setPort( xpr::ref(obj), as<int>(s1) ) -- Eric Niebler BoostPro Computing http://www.boostpro.com