Standard Library · meta

class AttrArg

One argument of an attribute, with a slot for every primitive form.

since 0.1.0-alpha.1linuxwindowswasm

Overview

Attribute fields are int, float, bool or string, so an argument carries four values and only the one matching the attribute's field type is meaningful. The typed accessors on Attr (argStr, argInt, argBool, argFloat) pick the right slot for you.

Examples

attribute Column { string col = ""; int width = 0; }
attribute Inspect { }

rule inspect {
    match @Inspect(i) on class C
    inject `Array<string> slots() => [ $for s in C.fields.where((f) => f.hasAttr("Column")).map((f) =>
        f.attributes.at(0).args.at(0).s + "," + f.attributes.at(0).args.at(1).i.toString() + "," +
        f.attributes.at(0).args.at(1).present.toString()) : $s ];` at member of C
}

@Inspect
class User {
    @Column("full_name", 40) string name;
    @Column("id") int id;
}

console.writeln(User().slots().joinToString("; "));

full_name,40,true; id,0,false

Fields

b

bool b

The value when the attribute field is a bool.

f

float f

The value when the attribute field is a float.

i

int i

The value when the attribute field is an int.

present

bool present

true when the argument was written at the use site, false when it took its default.

s

string s

The value when the attribute field is a string.

See also

• Attr — An attribute written on a field or method, with the values of its arguments.