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Opened 6 years ago

Closed 6 years ago

Last modified 5 years ago

#2831 closed Feature Request (Rejected)

Function Binding

Reported by: anonymous Owned by:
Milestone: Component: AutoIt
Version: Severity: None
Keywords: function binding Cc:

Description

Please create a function that can bind arguments to functions. The result of Bind(f,1,2) should be a function reference of f with an additional internal bound argument list [1, 2] (the internal list of bound arguments of normal function references would be empty). When calling $boundF(3), the call shoud be transformed to f(1,2,3).

Reason: Most functions expecting function references (_ArrayDisplay, last argument) don't call a special helper function instead of calling the passed function reference directly. That makes a general solution impossible. For each callback function a new function must be created, which is administratively expensive (compared to a simple function reference with bound arguments).

Func HandleActionCallback7 ($action, $direction)
	Return HandleAction ( _
		$HandleActionCallback7_objectToModify, _
		$action, _
		$direction)
EndFunc

There can be only as much callback functions as there are real functions. A function handling a callback called twice (the function, not the callback) would need at least two helper functions, and the logic to manage multiple callback functions. And if it's unknown how often the function is called...

Attachments (0)

Change History (5)

comment:1 follow-up: Changed 6 years ago by jchd18

I'm not the only one having found your request somehow obscure. Can you please post a short example of working current-state code you wish to replace and then the (pseudo-)code you have in mind for performing the same process?

comment:2 in reply to: ↑ 1 Changed 6 years ago by anonymous

Replying to jchd18:

I'm not the only one having found your request somehow obscure.

In what way?

Can you please post a short example of working current-state code you wish to replace and then the (pseudo-)code you have in mind for performing the same process?

external-functions.au3:

; These are external functions. I don't know how they're written, and I don't want to know.
Func ForEach (ByRef $array, $function)
	For $i = 0 To UBound ($array) - 1
		$function ($array [$i])
	Next
EndFunc
Func CreateForEachArray ($object0 = Default, $object1 = Default, $object2 = Default)
	Local $objects [@NumParams]
	For $i = 0 To @NumParams - 1
		$objects [$i] = Eval ("object" & $i)
	Next
	Return $objects
EndFunc

Currently:

#include "callback.au3" ; http://pastebin.com/Xqf8x54p
#include "external-functions.au3"

Func PrintObject ($prefix, $decimalPlaces, ByRef $object)
	ConsoleWrite ($prefix & " Object is at (" & Round ($object [0], $decimalPlaces) & "|" & Round ($object [1], $decimalPlaces) & ")." & @CRLF)
	Return $object ; Don't remove this line.
EndFunc
Func PrintObjects (ByRef $objects)
	Local Static $callCount = 0
	$callCount += 1
	Local $callbackIndex = ReserveCallback (CreateCallbackData (PrintObject, $callCount & ":", 1))
	ForEach ($objects, $callbackFunctions [$callbackIndex])
	; In this case, I don't need to save the callback. But if I do, then I might be unable to free it later
	; (custom GUICreate with ReserveCallback, but original GUIDelete without FreeCallback).
	FreeCallback ($callbackIndex)
EndFunc
Func CreateObject ($x, $y)
	Local $result = [$x, $y]
	Return $result
EndFunc

Local $objects = CreateForEachArray (CreateObject (10, 10), CreateObject (30, 20), CreateObject (20, 30))
PrintObjects ($objects)

Wishful thinking (and untested):

; No callback.au3, of course.
; ...
Func PrintObjects (ByRef $objects)
	Local Static $callCount = 0
	$callCount += 1
	ForEach ($objects, BindFunction (PrintObject, $callCount & ":", 1))
EndFunc
; ...

comment:3 follow-ups: Changed 6 years ago by jchd18

  • Resolution set to Rejected
  • Status changed from new to closed

You really should consider using AutoItObject instead of the construction you propose. Indeed, despite having "Object" suffixed to the function names CreateObject, PrintObject, PrintObjects, none of them applies to anything generic. Those functions should really be called CreateArray1D2ElementsNumbers, PrintArray1D2ElementsNumbers, PrintArray1D2ElementsNumbers as they can only process 1D arrays with 2 elements of number type (or strings but then decimalplaces doesn't make sense).

In a true OO approach, every processed datatype or container would have a constructor, destructor, a number of commonly used methods such as Print and possibly persistent storage. Then Print(this) would invoke the Print method of whatever type (class) this is: this could be any variant or array of any dimension and content, including nested contents (map containing strings, pointers, arrays of maps, arrays of double and structures).

From this point of view the proposal is way too specific to a unique clumsy coding style and should be discarded in favor of AutoItObject.

comment:4 in reply to: ↑ 3 Changed 6 years ago by anonymous

Replying to jchd18:

You really should consider using AutoItObject instead of the construction you propose.

You misunderstood me. This has nothing to do with OOP.
In many functional programming languages, this "binding" is implicit (either implicit currying or only unary functions), other languages have special functions for that (C++ (std::bind), Javascript (Function.prototype.bind), Python, Ruby, Scala, ...).

Indeed, despite having "Object" suffixed to the function names CreateObject, PrintObject, PrintObjects, none of them applies to anything generic.

If I had called them PrintPoint etc., then this wouldn't be a generic example. My apologies for that imprecise naming.

comment:5 in reply to: ↑ 3 Changed 5 years ago by anonymous

Replying to jchd18:
This was closed because of a misunderstanding, please reopen.

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