scala:"def foo = {1}"和"def foo {1}" [英] scala: 'def foo = {1}' vs 'def foo {1}'

问题描述

这些定义foo的每种形式的作用是什么?

what is going on in each of these forms of defining foo?:

scala> def foo = {1}
foo: Int

scala> foo
res2: Int = 1

但是:

scala> def foo {1}
foo: Unit

scala> foo

scala>

推荐答案

另请参见

在Scala中，如果方法声明的主体之前没有等号，则编译器会推断结果类型为 Unit

基本上声明一个不带=的函数意味着该函数返回Unit，并且编译器最后为您插入一个().必须使用=表示法声明应返回非Unit值的函数(尽管编译器当然可以从表达式的类型推断出返回类型).

Basically declaring a function with no = means that the function returns Unit and the compiler inserts a () for you at the end. A function which should return a non-Unit value must be declared with the = notation (although of course the compiler can infer the return-type from the expression's type).

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