Advanced Programming Techniques in D/

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Struct Literals and Static Members

Struct Literals and Static Members

You’ll get to learn about struct literals and static members in this lesson.

We'll cover the following...

Struct literals

Similar to being able to use integer literal values like 10 in expressions without needing to define a variable, struct objects can be used as literals as well.

Struct literals are constructed by the object construction syntax.

TimeOfDay(8, 30) // ← struct literal value

Let’s first rewrite the main() function using what we have learned. The variables will be constructed by the construction syntax and be immutable this time:

D
import std.stdio;
struct TimeOfDay {
    int hour;
    int minute; 
}
TimeOfDay addDuration(TimeOfDay start,TimeOfDay duration) {
    TimeOfDay result; 
    result.minute = start.minute + duration.minute; 
    result.hour = start.hour + duration.hour; 
    result.hour += result.minute / 60;
    result.minute %= 60; 
    result.hour %= 24;
    return result;
}
void main() {
    immutable periodStart = TimeOfDay(8, 30); 
    immutable periodDuration = TimeOfDay(1, 15);
    immutable periodEnd = addDuration(periodStart, periodDuration);
    writefln("Period end: %s:%s", periodEnd.hour, periodEnd.minute);
}

Note that periodStart and periodDuration need not be defined as named variables in the code above. Those are in fact temporary variables in this simple program, which are used only for calculating the periodEnd variable. They could be passed to addDuration() as literal values instead:

D
import std.stdio;
struct TimeOfDay {
    int hour;
    int minute; 
}
TimeOfDay addDuration(TimeOfDay start,TimeOfDay duration) {
    TimeOfDay result; 
    result.minute = start.minute + duration.minute; 
    result.hour = start.hour + duration.hour; 
    result.hour += result.minute / 60;
    result.minute %= 60; 
    result.hour %= 24;
    return result;
}
void main() {
    immutable periodEnd = addDuration(TimeOfDay(8, 30), TimeOfDay(1, 15));
    writefln("Period end: %s:%s", periodEnd.hour, periodEnd.minute);
}

Static members

Although objects mostly need individual copies of the struct's ...