英文:
How can I define a `const *DataType`
问题
我正在使用Go语言编写一个Lisp变种，并且想要为Nil和EmptyList定义常量。这些常量将在整个代码库中被引用，但我希望防止它们被意外重新定义。
// 空列表的表示var EmptyList = (*List)(nil)
在这里我不能使用const的原因有两个：
const定义不能是nilconst定义不能是指针
我有哪些选项可以确保EmptyList始终是nil指针？
英文:
I'm writing a Lisp variant in Go and want to define constants for Nil and EmptyList. These will be referenced throughout the codebase, but I want to prevent them from being accidentally re-defined.
// Representation of the empty listvar EmptyList = (*List)(nil)
I can't use a const here for two reasons:
constdefinitions cannot benilconstdefinitions cannot be pointers
What options do I have to ensure EmptyList is always the nil pointer?
答案1
得分: 1
在Go语言中，可以使用函数。例如，
package mainimport "fmt"type List struct{}func IsEmptyList(list *List) bool {// 表示空列表return list == (*List)(nil)}func main() {fmt.Println(IsEmptyList((*List)(nil)))}
输出结果：
true
该函数将被内联。
$ go tool compile -m emptylist.goemptylist.go:7: can inline IsEmptyListemptylist.go:13: inlining call to IsEmptyListemptylist.go:7: IsEmptyList list does not escapeemptylist.go:13: IsEmptyList((*List)(nil)) escapes to heapemptylist.go:13: main ... argument does not escape$
英文:
In Go, use a function. For example,
package mainimport "fmt"type List struct{}func IsEmptyList(list *List) bool {// Representation of the empty listreturn list == (*List)(nil)}func main() {fmt.Println(IsEmptyList((*List)(nil)))}
Output:
true
The function will be inlined.
$ go tool compile -m emptylist.goemptylist.go:7: can inline IsEmptyListemptylist.go:13: inlining call to IsEmptyListemptylist.go:7: IsEmptyList list does not escapeemptylist.go:13: IsEmptyList((*List)(nil)) escapes to heapemptylist.go:13: main ... argument does not escape$
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论