Allow stricter structural typing · Issue #391 · microsoft/TypeScript (original) (raw)

Say I have the following:

interface Options {
    doSomethingSpecial?: boolean
}

function configure(options: Options) {}
configure({});

The preceding (correctly) does not flag any issues. However, say I change the function call to:

configure({doSomethingSuper: true});

This also does not flag any issues. I understand that in many (most?) cases this is the desired behavior, but in other cases it seems that a stricter matching (ie, you don't have to specify "doSomethingSpecial" but you can't specify anything else either) would be desirable. There are at least two instances that I can think of where this applies:

1. Catching typos
2. (more importantly) Compile-time checking after a refactoring of "doSomethingSpecial" to be named something else

Perhaps some new syntax for enabling this mode would be useful. For example:

function configure(options: Options!) {}