scala - 产量语法
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scala - yield syntax
提问by Void Main
I'm reading a book on scala programming (the Programming in Scala), and I've got a question about the yield syntax.
我正在阅读一本关于 Scala 编程的书（Scala 编程），我有一个关于 yield 语法的问题。
According to the book, the syntax for yield can be expressed like: for clauses yield body
根据这本书，yield 的语法可以表示为： for 子句 yield body
but when I try to run the script below, the compiler complains about too many arguments for getName
但是当我尝试运行下面的脚本时，编译器抱怨 getName 的参数太多
def scalaFiles =
for (
file <- filesHere
if file.isFile
if file.getName.endsWith(".scala")
) yield file.getName {
// isn't this supposed to be the body part?
}
so, my question is what is the "body" part of the yield syntax, how to use it?
所以，我的问题是 yield 语法的“主体”部分是什么，如何使用它？
回答by om-nom-nom
Shortly, any expression (even that that return Unit), but you must enclose that expression into the brackets or just drop them down (works only with a single statement expressions):
很快，任何表达式（即使是返回 Unit 的表达式），但您必须将该表达式括在括号中或将它们下拉（仅适用于单个语句表达式）：
def scalaFiles =
for (
file <- filesHere
if file.isFile
if file.getName.endsWith(".scala")
) yield {
// here is expression
}
code above will work (but with no sense):
上面的代码可以工作（但没有意义）：
scalaFiles: Array[Unit]
Next option is:
下一个选项是：
for(...) yield file.getName
and as a tip, you can rewrite your for comprehension like that:
作为提示，您可以像这样重写理解：
def scalaFiles =
for (
file <- filesHere;
if file.isFile;
name = file.getName;
if name.endsWith(".scala")
) yield {
name
}
