User-Defined Constructors and the Use of static opCall()

User-defined constructors

You have already learned about the behavior of the compiler-generated constructor. Since that constructor is suitable for most cases, there is no need to define a constructor by hand.

Still, there are cases where constructing an object involves more complicated operations than assigning values to each member in order. Let’s consider this example:

struct Duration {
    int minute; 
}

The compiler-generated constructor is sufficient for this single-member struct:

time.decrement(Duration(12));

Since that constructor takes the duration in minutes, the programmers would sometimes need to make calculations:

// 23 hours and 18 minutes earlier
time.decrement(Duration(23 * 60 + 18));

// 22 hours and 20

...