C++ 模板的结构化文本中是否有等效项？

Question

I'm new to Structured Text programming and I'm currently working on TwinCat3.

I would like to specify array sizes inside my code without polluting the global namespace with additional constants. I think it would be useful, especially in creating a library.

I can't find a solution to this problem. In case there isn't one, can you tell me the best practice to solve this problem? The only solutions I see are:

• use global variables
• allocate in the heap

Answer 1

You can try something like this.

class <someclass>{
    public:
       static const int ARR_SIZE;
}
const int X::ARR_SIZE = <somevalue>;

since the variable is class scope, you wouldn't pollute the global namespace. alternatively you can create a namespace your own and define the static const variable inside of it such as

namespace <somename>{
 static const int ARR_SIZE = <somevalue>;
 // other definitions.
}

in this case the const variable read-only and accessible inside the namespace and can be accessed through::ARR_SIZE outside the namespace.