From ae0aedbb12bc47086a8a0d147196b519598536e3 Mon Sep 17 00:00:00 2001 From: Zheng Ping Date: Fri, 26 May 2017 22:52:14 +0800 Subject: [PATCH] Update ch17-02-trait-objects.md --- src/ch17-02-trait-objects.md | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/src/ch17-02-trait-objects.md b/src/ch17-02-trait-objects.md index f787727..1e9116a 100644 --- a/src/ch17-02-trait-objects.md +++ b/src/ch17-02-trait-objects.md @@ -277,14 +277,9 @@ trait Foo: Sized { Trait`Sized`现在就是trait`Foo`的一个*超级trait*, 也就是说trait`Foo`需要实现了`Foo`的类型(即`Self`)是`Sized`. 我们将在第19章中更详细的介绍超trait(supertrait). -The reason a trait like `Foo` that requires `Self` to be `Sized` is not allowed -to be a trait object is that it would be impossible to implement the trait -`Foo` for the trait object `Foo`: trait objects aren't sized, but `Foo` -requires `Self` to be `Sized`. A type can't be both sized and unsized at the -same time! - -For the second object safety requirement that says all of a trait's methods -must be object safe, a method is object safe if either: +像`Foo`那样要求`Self`是`Sized`的trait不允许成为trait对象的原因是不可能为trait对象`Foo`实现trait`Foo`: trait对象是无确定大小的，但是`Foo`要求`Self`是`Sized`. 一个类型不可能同时既是有大小的又是无确定大小的. + +第二点说对象安全要求一个trait的所有方法必须是对象安全的. 一个对象安全的方法满足下列条件: * It requires `Self` to be `Sized` or * It meets all three of the following: