隐式输入；为什么只是局部变量? [英] Implicit typing; why just local variables?

问题描述

有谁知道或想推测为什么隐式类型仅限于局部变量?

Does anyone know or care to speculate why implicit typing is limited to local variables?

var thingy = new Foo();

但为什么不...

var getFoo() {
    return new Foo(); 
}

推荐答案

Eric Lippert 就此主题撰写了整篇博文.

Eric Lippert did an entire blog post on the subject.

• https://docs.microsoft.com/en-us/archive/blogs/ericlippert/why-no-var-on-fields

总而言之，主要问题是它需要对 C# 编译器进行重大的重新架构才能这样做.声明目前以单程方式处理.由于能够在推断变量之间形成循环，这将需要多次通过.VB.NET 也有大致相同的问题.

In summary, the main problem is that it would have required a major re-architecture of the C# compiler to do so. Declarations are currently processed in a single pass manner. This would require multiple passes because of the ability to form cycles between inferred variables. VB.NET has roughly the same problem.

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