Jez,

There's a fair number of tools like MatrixX's Simulink, Boeing's Easy5 & Woodward Governor's GAP that attempt to do a similar thing. As long as the 'components' are in the catalog the concept works pretty well. Exceptions usually require a new component in the catalog or access to the root language implementing the catalog components. Regardless, the catalog components still need to be linked together and sometimes, compiled first.

Bruce