Dependency Injection for Procedural Programming

Question

Suppose I\'ve decided to write a large application in C, or any other procedural programming language. It has functions with call-dependencies that look like this:

Answer 1

I like this question. It gets a bit tricky in procedural languages.... but I think you can borrow an idea from the OO world where folks often use constructor overloading to handle some of the DI work. So for example you would use the default constructor that sets up all the dependencies as usual... but then also have another constructor that allows the dependencies to be injected.

Since you are procedural... I think you could use function overloading to handle this for you. Also when you are testing you only would need to mock out B1 & B2 when calling A... so you could simplify your DI for that purpose. In other words if you really only using DI for unit testing then you don't have to inject the whole tree of dependcies only the first level dependecies...

So from A you might have...

int A(int input){
// create function point to b1 & b2 and call "return A(input, {pointer to b1},{pointer to b2})"
}

forgive my psuedo code it has been a long time since I did C.