Bug: this type not allowed in constructor

[nin-jin]

class X {
    foo = 1
    constructor( setup? : ( obj : this ) => void ) {
        if( setup ) setup( this )
    }
}

var x = new X( obj => {
    obj.foo = 2 // Ok, allowed
    // obj.bar = 3 // Ok, not allowed
} )

A 'this' type is available only in a non-static member of a class or interface.

[jeffreymorlan]

Exposing this to outside code from a constructor is an anti-pattern; subclasses haven't had the chance to do their own initialization yet:

class X {
    constructor(setup: (obj: any) => void) { setup(this); }
}
class Y extends X {
    a: string[] = [];
}
var y = new Y(obj => {
    obj.a.push('foo'); // fails because obj.a is not set yet
});

[mhegazy]

Duplicate of #5863

[nin-jin]

@jeffreymorlan agree for this case :-) I am using this pattern now:

new X().setup( obj => {
    obj.foo = 2 // Ok, allowed
    // obj.bar = 3 // Ok, not allowed
} )

But it would be cool if we can use this:

new X().setup({
    foo : 2 , // Ok, allowed
    // foo : '3' , // Ok, not allowed
    // bar : 4 , // Ok, not allowed
})

But how to implement of strong intersection of type this and type of agrument?