README.md

mindscreen JavaScript decorators

A package to gather JS decorators from projects at mindscreen.

TypeGuard

Specify expected argument types on class methods to ensure correct types when calling them. Throws a TypeError if called with an incorrect type or a ReferenceError, if a required argument is missing.

// import { TypeGuard } from 'mindscreen-decorators';
// const { TypeGuard } = require('mindscreen-decorators');

class A {}
class B extends A {}
class C {}

class Example {

    @TypeGuard({
        a: A.prototype,
        b: { required: true, type: 'int' },
        c: 'boolean'
    })
    foo(a, b, c, d) {
        // ...
    }

    @TypeGuard({
        value: 'string'
    })
    set bar(value) {
        // ...
    }
}

const a = new A();
const b = new B();
const c = new C();
const e = new Example();

e.foo(a, 12); // OK
e.foo(a); // ReferenceError: The property 'b' on method 'Example::foo' is required and not set.
e.foo(c, 12); // TypeError: The property 'a' on method 'Example::foo' should be of type 'A', got C.
e.foo(b, 12); // OK

Note that not all arguments have to be mentioned in the @TypeGuard options. Arguments not explicitly configured to be required, won't act this way. Arguments can be set to be required without configuring a type. Alternatively any can be used.

The spread-operator (...args) can't be configured, as it is removed by transpiling your source.