Swift的GeneratorOf< T>疯狂的初始化 [英] Swift's GeneratorOf<T> crazy init

问题描述

GeneratorOf创建一个通用的生成器（和序列）：

  struct GeneratorOf< T> ：Generator，Sequence {
 init（_ next：（） - > T？）
 init< G：Generator where T == T>（_ self_：G）
 func next ） - > T？ 
 func generate（） - > GeneratorOf< T> 
} 
  

我不明白的是第二个init：

  init< G：Generator where T == T>（_ self_：G）
  pre> 
 
 
为什么在地球上需要说明 T == T  ?? 
 
 
 
这是（_ self_：G）是什么意思？
 
 
 
谢谢Swift的主要优点之一是比Objective C更简单的语法： -  P 
解决方案
 Swift stdlib头自动生成器中的一个错误。当解析类型时，它们在某些地方替换等价类型，它们不应该。这里的实际定义应该是：
  init< G：Generator where Generator.Element == T>（_ self_： G）
  
但由于 Generator.Element 与 T 相同，该工具将替换它。苹果一直在努力解决这个问题。
 
 
 
 （_ self_：G）是标准语法，我没有看到在别处使用，除了 SequenceOf ，这可能是由同一个人写的。我怀疑这是开发人员命名的变量，而不是有一些更深层次的意义。
 
 
 
记住，stdlib头并不是一个正常头。 Swift没有标题。 Apple 
 
 
 
  Chris Lattner在版本中对此进行了评论。 
 
GeneratorOf creates a generic Generator (and Sequence):
struct GeneratorOf<T> : Generator, Sequence {
    init(_ next: () -> T?)
    init<G : Generator where T == T>(_ self_: G)
    func next() -> T?
    func generate() -> GeneratorOf<T>
}
The line I don't understand is the second init:
init<G : Generator where T == T>(_ self_: G)
Why on Earth is it necessary to state that T == T??

What is this (_ self_: G) supposed to mean??

Thanks goodness that one of Swift major advantages is a much simpler syntax than Objective C... :-P
解决方案
This is a bug in the Swift stdlib header auto-generator. When resolving types, they replace equivalent types in some places they shouldn't. The actual definition here is supposed to be:
init<G : Generator where Generator.Element == T>(_ self_: G)
But since Generator.Element is the same as T, the tool replaces it. Apple's been working on fixing that.

(_ self_: G) is standard syntax, though an admittedly unusual style that I haven't seen used elsewhere, except for in SequenceOf, which was probably written by the same person. I suspect it's just how the developer named the variable, rather than having some deeper meaning.

Remember, the stdlib header isn't a "normal" header. Swift doesn't have headers. Apple does a special Apple-only trick to allow one.

Chris Lattner commented on this in the devforms.

                        
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