On 1/6/2011 11:39 AM, Hossein Haeri wrote:
Dear Eric,
I will certainly have another read over make_expr. But, I have a feeling that I might not have explained what I need very well. So, with some connection to the function streaming thing we were in contact on previous threads, here is an example:
MyClass mc(_1 >> &f >> &g >> &h); mc.set_input(-61.1); cout << mc.value();//returns h(g(f(-61.1)))
Now, are you telling me that I can store that "_1 >> &f >> &g >> &h" bit in a data member of mc using make_expr? If so, what will the type of that data member be? Or, are you suggesting a totally different design?
Ah. That part (the usage) wasn't clear. No, you can't use it like that. I would suggest transforming the expression into a unary function object (see my article on cpp-next.com about function composition), and be sure your transform also stores everything by value. (Or pass everythying through deep_copy.) Then store the resulting unary function in a boost::function, so it's type-erased. HTH, -- Eric Niebler BoostPro Computing http://www.boostpro.com