如何解决 2.8.0 中的 Scala 源不兼容问题？
有一些源代码与 Scala 2.8.0 不兼容的情况。例如，创建匿名 Seq 曾经需要定义抽象 def elements : Iterator[A]，现在称为 def iterator : Iterator[A]代码>.
对我来说，“强力”解决方案是创建两个与不同主要 scala 版本保持一致的分支。
是否有通用技术可以使这样的代码在两个系统下编译？
// Note: this code resembles techniques used by xml.NodeSeq
trait FooSeq extends Seq[ Foo ] {
def internal : Seq[ Foo ]
def elements = internal.elements
def iterator = internal.iterator // Only compiles in 2.8
// need to remove for 2.7.X
}
There are a few cases of source incompatibilities with Scala 2.8.0. For example, creating an anonymous Seq once required defining the abstract def elements : Iterator[A], which is now called def iterator : Iterator[A].
To me, a "brute force" solution is to create two branches that align to the different major scala versions.
Are there general techniques so that code like this will compile under both systems?
// Note: this code resembles techniques used by xml.NodeSeq
trait FooSeq extends Seq[ Foo ] {
def internal : Seq[ Foo ]
def elements = internal.elements
def iterator = internal.iterator // Only compiles in 2.8
// need to remove for 2.7.X
}
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在某些情况下，用法完全不同，您必须进行更改。但在几乎所有情况下（例如上面的 elements 代码），2.7 样式只是在 2.8 中被弃用，而不是完全消失。如果您可以让 2.8 用户留下弃用警告（编辑：如果他们编译您的代码，否则您自己就会收到警告），只需根据旧功能实现新功能即可：
否则，我会推荐您的功能调用暴力解决方案。使用足够聪明的 VCS，这样您实际上就不必编写两次代码（Git、Bazaar、Mercurial）和分支。
There are a few cases where usage is simply different and you must change. But in almost all cases--such as the elements code above--the 2.7 style is simply deprecated in 2.8, not gone altogether. If you're okay leaving your 2.8 users with deprecation warnings (edit: if they compile your code, otherwise you'll just have the warnings yourself), just implement the new features in terms of the old:
Otherwise, I would recommend what you call the brute force solution. Use a sufficiently clever VCS so that you don't actually have to write much code twice (Git, Bazaar, Mercurial) and branch.