[英]Typescript: Is it possible to evaluate generic type into string literal?
Is it possible to evaluate generic type into a string literal without being explicit?是否可以在不明确的情况下将泛型类型评估为字符串文字?
Here is an example what I have in mind:这是我想到的一个例子:
function foo<T>(type: T): { type: T } {
return { type };
}
// type is { type: string } I would like it to be { type: 'FooBar' } without being explicit
const bar = foo('FooBar');
// is it possible not to do this and get same result?
const fooBar = foo<'FooBar'>('FooBar');
const barFoo = foo('FooBar' as const);
I am also bit surprised Literal Narrowing doesnt propagate to foo
function and instead it defaults to string
type.我也有点惊讶Literal Narrowing不会传播到
foo
function 而是默认为string
类型。
const test = 'FooBar';
const barFoo = foo(test);
However, when I explicity specify type there is no problem.但是,当我明确指定类型时,没有问题。
const test: 'FooBar' = 'FooBar';
const barFoo = foo(test);
Well this is where we started.好吧,这就是我们开始的地方。
With a little bit of fiddling in foo
function:稍微摆弄一下
foo
function:
function foo<T extends string>(type: T): { type: T } {
return { type };
}
const test = 'FooBar';
const barFoo = foo(test);
I was looking at intellisense result when I peeked at expression and it now propagates the type.当我查看表达式时,我正在查看智能感知结果,它现在传播了类型。
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