I remember trying to do the "construct a function name as a string and call it" thing in VB6 many years ago before I "knew better". Any idea what that functionality is called? I always wondered why languages wouldn't let you do that.
>I remember trying to do the "construct a function name as a string and call it" thing in VB6 many years ago before I "knew better". Any idea what that functionality is called?
It's called by various names - not sure if there is an official one - such as dispatch tables, jump tables, dynamic dispatch, etc. It's a pretty old technique, I would say it probably dates from the time of early high-level languages, and I seem to remember that it was used in assembly languages too (so probably even earlier), by using various addressing modes (indexed, indirect indexed, etc. (those terms are from long-forgotten 6502 instruction set BTW), storing the address of a function at a location and then jumping to that address (where the address is dynamically set at run time by some other bit of code based on some condition), etc.
I don't think there's another widely used name for it except dynamic or virtual dispatching (with inline caching of the lookup table). C is too low level and simple a language to have it in the string lookup form and in C++/Rust name mangling, symbol stripping from binaries, and generics would make the feature very difficult to implement and rather unergonomic. C#/F# and CLR C++/VB probably already have this in the form of the reflection/.Net runtime APIs (including JIT for generics) but implementing it in C++ or Rust would be very complex and it would be yet another feature that bifurcates the language ecosystem (like heap allocation for embedded). Python and Javascript do have this feature but you still have to have access to the scope to do it (self['fn_name'] or this['fn_name']) and this implementation exists in one way or another in most dynamic languages.
You can do this as a hack in most compiled languages by exporting symbols from a shared library and just using the OS specific dynamic linker but this is ugly, slow, and pointless in a static language.
