Boo Primer: [Part 11] Structs

Added by Cameron Kenneth Knight

Definition: Struct - Short for structure, a term meaning a data group made of related variables.

The main way structs are different than classes is that they are value types instead of a reference types. This means that whenever you return this value, or set one equal to another, it is actually copying the data not a reference to the data. This is handy, because if it is declared without a value, it will default to something besides null. It also cannot be compared to null. This eliminates a lot of error checking associated with reference types.

Structs also cannot inherit from classes, nor can classes inherit from structs. Structs can however, inherit from interfaces.

Unlike some other languages, structs can have methods.

Declaring a Struct

Declaring a struct is very similar to declaring a class, except that the name is changed.

Declaring a Struct

struct Coordinate:
    def constructor(x as int, y as int):
        _x = x
        _y = y

    _x as int
    _y as int

c as Coordinate
print c._x, c._y
c = Coordinate(3, 5)
print c._x, c._y

// Output:
// 0 0
// 3 5

Here you can see that the struct was instanced without being called, showing the how a struct is a value.

Exercises

1. Figure out a good exercise for this section.

Go on to Part 12 - Namespaces

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