f# - How do I overload operators for WPF containers? -

type addertype() =     /// appends container.     static member (+)         (cont:dockpanel,child:#uielement) =         cont.children.add child |> ignore         child 

when make class above , try this.

let dock = dockpanel() let win = window(title = "check window style", content = dock) let menu = dock + menu() 

i error none of types 'dockpanel,menu' support operator '+'. inspired make above phil trelford's binding example goes this:

type dependencypropertyvaluepair(dp:dependencyproperty,value:obj) =     member this.property = dp     member this.value = value     static member (+)          (target:#uielement,pair:dependencypropertyvaluepair) =         target.setvalue(pair.property,pair.value)         target 

the above reason works. have no idea why. possible overload + or other operator elegantly add controls containers?

operators defined inside class work if 1 of arguments instance of class, can define operator global operator:

let (++) (cont:dockpanel) (child:#uielement) =     cont.children.add child |> ignore     child 

the following should work:

let dock = dockpanel() let win = window(title = "check window style", content = dock) let menu = dock ++ menu() 

but honest, don't think kind of problem place using custom operators. using + here confusing, because not adding 2 things in sense. operator not commutative, e.g. (a ++ b) <> (b ++ a).

i think more idiomatic code define named function , use |>:

let appendto (cont:dockpanel) (child:#uielement) =     cont.children.add child |> ignore     child  let dock = dockpanel() let win = window(title = "check window style", content = dock) let menu = menu() |> appendto dock