英文:
using a label with anonymous function
问题
在sync包的源代码中，Pool结构体内有一个新的函数，定义如下：
type Pool struct {
local unsafe.Pointer // local fixed-size per-P pool, actual type is [P]poolLocal
localSize uintptr // size of the local array
// New optionally specifies a function to generate
// a value when Get would otherwise return nil.
// It may not be changed concurrently with calls to Get.
New func() interface{}
}
在由Facebook创建的golang stack trace包的第103行，有一个匿名函数定义在sync pool结构体内，如下所示，带有New:标签：
var pcsPool = sync.Pool{
New: func() interface{} {
return make([]uintptr, maxStackSize)
},
}
根据源代码中的注释，我猜测Facebook包已经“指定了一个函数，在Get返回nil时生成一个值”，但为什么要这样定义New:呢？
英文:
There's a New function inside a Pool struct in the source code of the sync package that's defined like this
type Pool struct {
local unsafe.Pointer // local fixed-size per-P pool, actual type is [P]poolLocal
localSize uintptr // size of the local array
// New optionally specifies a function to generate
// a value when Get would otherwise return nil.
// It may not be changed concurrently with calls to Get.
New func() interface{}
}
At line 103 of a golang stack trace package created by Facebook, there's an anonymous function defined inside a sync pool struct like this with the New: label:
var pcsPool = sync.Pool{
New: func() interface{} {
return make([]uintptr, maxStackSize)
},
}
So, going from the comments in the source code, I'm assuming that the Facebook package has "specified a function to generate a value when Get would otherwise return nil," but why might it be defined with New: like this?
答案1
得分: 2
New不是一个标签，它是sync.Pool中的一个字段名。
type Pool struct {
// New optionally specifies a function to generate
// a value when Get would otherwise return nil.
// It may not be changed concurrently with calls to Get.
New func() interface{}
// contains filtered or unexported fields
}
它与以下示例中的N没有区别：
type T struct {
N int
}
t := T{
N: 1,
}
英文:
New isn't a label, it's a field name in a sync.Pool
type Pool struct {
// New optionally specifies a function to generate
// a value when Get would otherwise return nil.
// It may not be changed concurrently with calls to Get.
New func() interface{}
// contains filtered or unexported fields
}
It's no different than N in the following example
type T struct {
N int
}
t := T{
N: 1,
}
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