Sounds like a job for Boost.Fusion ;)

Zitat von Noman Javed :

Can someone guide me how to transform an expression both at compile time and at runtime? I explain by an example

Suppose I want to transform the following expression like that foo(f,other(g,bar)) --> other(g,foo(f,bar)) where bar is an Array and the "foo" and "other" are the higher order functions.

I can write the metafunction for transforming the type of the expression i.e from Foo > --> Other >

I want to execute this expression in the following way Array result = foo(f, other(g, bar)) where within the body of the operator= overload of the Array class I have the function transform to transform this expression as said above.

if I understand you correctly you want to pass a function object to operator= and transform it? then your C++ syntax would be: Array result = bind(foo,f,bind(other,g,bar)); if so, I'm not aware of any way to "extract the curry" out of a bind() result. the functional stuff in Boost.Fusion (fused function objects) might be helpful in building such a bind(). joel, has there been an attempt to make Fusion and Bind work together in this way? the result of a bind() could be expressed as a fused function object plus a fusion sequence. but bind() seems to store the arguments in its own argument list type, and doesn't expose it.