Dynamic source code in C++ [closed]

Answer 1

The best way to embed and eval code within a C++ application is probably to use a scripting language like python. Use Boost.Python, "a C++ library which enables seamless interoperability between C++ and the Python programming language."

Answer 2

How about function pointers?

Answer 3

C++ is a compiled language, and thus, there is no equivalent to "eval()".

For the specific example you mention, you could make a function registry that maps inputs (strings) to outputs (function pointers) and then call the resultant function.

There are several C++ interpreter libraries that are available, although performance will be very poor, they may accomplish what you want. Google search for "C++ interpreter". I've seen results for "Ch", "CINT" and "clipp"

Answer 4

What you want is reflection. It's not supported by default in C++, but many people have written comprehensive reflection systems for all sorts of purposes. One that comes to mind off the top of my head is binding C++ functions to a custom scripting language.

Others have mentioned using a switch statement (or more accurately and if/else tree). This is about as simple as a reflection system is likely to come... and it is probably the best solution for your project. Reflection in C++ is a fairly advanced technique and often requires a lot of additional code... sometimes even custom preprocessors.

Also note that for security purposes, eval() is almost never something you want to be using in any language.

Answer 5

You can't do that in C++. It is a mandatorily-compiled language.

A lot of information that would be necessary to implement eval() is lost at run-time anyway.

Answer 6

There are two ways of doing this :

1. Dynamic Loading

   • Windows: GetModuleFileName() with hModule = NULL this gives the path of the executable. Use LoadLibrary(Executable_Name) to load itself in the memory.
   • Linux : Use dloopen() with NULL and it loads itself in memory.

   In both Windows and Linux you can define a void* (function*)() pointer. This always works with all signatures without parameters. This does not work on class methods.

2. Using Namespace System

   This namespace would be easy you can use the Inspect functionality and InvokeMember methods to dynamically call class methods and access variable from inside the class.