5.4. With Statement

DANGER

Experimental Feature

The with statement creates scoped blocks in which members of the given expression can be accessed without repeating its name.

with ( [ ( var | unowned var | type-name identifier ) = ] expression ) embedded_statement

struct Color {
    int red;
    int green;
    int blue;
}

void main ()
{
    Color c = {255, 0, 0};

    print ("red: %d, green: %d, blue: %d\n", c.red, c.green, c.blue);
    with (c) {
        red = 1;
        green = 2;
        blue = 3;
    }

    // red: 1, green: 2, blue: 3
    print ("red: %d, green: %d, blue: %d\n", c.red, c.green, c.blue);
}

The with statement is a convenient way to access members of a struct or class without prefixing them with the object name.

WARNING

Use with statements carefully, as they can make programs harder to read and understand.

Variable Declarations in With Statement

It's also possible to do variable delcarations within with statement parentheses. Keeping the Color variable in the scope of the with statement block:

public struct Color {
    int red;
    int green;
    int blue;
}

void main ()
{
    with (Color c = Color () { red = 1, green = 2, blue = 3 }) {
        // red: 1, green: 2, blue: 3
        print ("red: %d, green: %d, blue: %d\n", red, green, blue);
    }
}