无法在类型上定义 (?) 运算符重载:
type Foo =
val s : string
new(s) = { s = s }
static member (?) (foo : Foo, name : string) = foo.s + name
let foo = Foo("hello, ")
let hw = foo? world
// error FS0043: The member or object constructor 'op_Dynamic'
// takes 2 argument(s) but is here given 1. The required signature
// is 'static member Foo.( ? ) : foo:Foo * name:string -> string'.
如果我对操作符定义使用独立的 let 绑定(bind),一切正常:
let (?) (foo : Foo) (name : string) = foo.s + name
let hw = foo? world
但我需要直接为
op_Dynamic
类型指定 Foo
运算符。第一个代码片段有什么问题?使用
F# 1.9.7.4
@ Visual Studio 2010 Beta2 最佳答案
也许有一种更简单的方法(我会看看),但这会在紧要关头:
type Foo =
val s : string
new(s) = { s = s }
static member (?)(foo : Foo, name : string) =
foo.s + name
let inline (?) (o:^T) (prop:string) : ^U =
(^T : (static member (?) : ^T * string -> ^U)(o,prop))
let foo = Foo("hello, ")
let hw = foo ? world
printfn "%s" hw
关于dynamic - F# 动态查找运算符 (?) 重载,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/1621250/