与对象相交时字符串文本与字符串类型不兼容

按预期工作:

// @flow

type FontName = string
const doSomethingWithFontName = (fontName: FontName) => console.log(fontName)

type StrictFontName = 'Arial' | 'Verdana' | 'Times'
const doSomethingWithStrictFontName = (fontName: StrictFontName) => doSomethingWithFontName(fontName)

doSomethingWithStrictFontName('Times')

打电话 doSomethingWithFontName 从 doSomethingWithStrictFontName StrictFontName 只包含字符串,因此我可以调用 多索梅辛维方名称 严格字体名

// @flow

type Typography = { 
  fontName?: string; 
}
const doSomethingWithTypography = (typography: Typography) => console.log(typography)

type StrictTypography = Typography & { 
  fontName?: 'Arial' | 'Verdana' | 'Times'; 
}
const doSomethingWithStrictTypography = (typography: StrictTypography) => {
  doSomethingWithTypography(typography)
}

doSomethingWithStrictTypography({fontName: 'Times'})

我只是把我们的严格对象转发给一个更宽松的函数,为什么这不起作用?流可以分辨 StrictTypography 的 fontName 还是一根绳子对吗?

thread 并提出将超级类型作为一个解决方案作为一个接口:

// @flow

// Interface instead of type
interface Styles { 
  fontName?: string; 
}

const doSomethingWithStyling = (styles: Styles) => console.log(styles)

type StrictStyles  = Styles & { 
  fontName?: 'Arial' | 'Verdana' | 'Times'; 
}
const doSomethingWithStrictStyling = (styles: StrictStyles) => {
  doSomethingWithStyling(styles)
}

doSomethingWithStrictStyling({fontName: 'Times'})

这似乎可行,但我不确定这是否是正确的方法。如果我导入这个接口,我会得到一个 Use of future reserved word in strict mode ...

here