c++ #define a macro with brackets?

Question

Instead of doing the following everytime

start();

// some code here

stop();

I would like to define some sort of macro which makes it possible to write like:

startstop()
{

//code here

}

Is it possible in C++?

Answer 1

You can do something very close using a small C++ helper class.

class StartStopper {
public:
    StartStopper() { start(); }
    ~StartStopper() { stop(); }
};

Then in your code:

{
    StartStopper ss;
    // code here
}

When execution enters the block and constructs the ss variable, the start() function will be called. When execution leaves the block, the StartStopper destructor will be automatically called and will then call stop().

Answer 2

The idiomatic way of doing this in C++ is called Resource Acquisition Is Initialization, or shortly RAII. In addition to providing what you want, it also has the added benefit of being exception safe: the stop function will be called even if your code throws an exception.

Define a guard struct:

struct startstop_guard
{
    startstop_guard()
    {
        start();
    }
    ~startstop_guard()
    {
        stop();
    }
};

and then rewrite your code this way:

{
    startstop_guard g;
    // your code
}

The guard's destructor (and thus the stop function) will be called automatically at the end of the enclosing block.