Hi Community,
It's been a while I wrote a blog post here.
You can follow more such tricks on —
- Github: https://github.com/rachitiitr/modern-cpp-tricks
- Discord: https://bit.ly/discord-rachit
- YouTube: https://bit.ly/rachityoutube
How debug macros work?
Straight to the point, I have often used the debug macro which stringifies the variable names and their values.
#define deb(x) cout << #x << " " << x
int ten = 10;
deb(ten); // prints "ten = 10"
This is often useful in debugging.
The Problem with this macro — its not scalable
However, when you have multiple variables to log, you end up with more deb2 and deb3 macros.
#define deb(x) cout << #x << " " << x
#define deb2(x) cout << #x << " " << x << " " << #y << " " << y
#define deb3(x, y, z) cout << #x << " " << x << " " << #y << " " << y << " " << #z << " " << z
This is not scalable.
Solution using a powerful macro
Here is the solution using variadic macros and fold expressions,
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values) {
cout << vars << " = ";
string delim = "";
(..., (cout << delim << values, delim = ", "));
}
int xx = 3, yy = 10, xxyy = 103;
deb(xx); // prints "xx = 3"
deb(xx, yy, xxyy); // prints "xx, yy, xxyy = 3, 10, 103"
Hope this helps, this is going to my template for sure
