Objects add inverse order methods

[crocodile]

I'm not sure if this is a good proposal, but in the use of AutoHotkey, I will often use inverse traversal, which is, of course, very cumbersome to implement.
I searched some other languages and it seems they all support inverse order traversal.


This is the implementation of inverse order using AutoHotkey:

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arr := []
for k, v in Map("a", 1, "b", 2)
	arr.InsertAt(1, [k, v])

for n in arr
	;

This is the built-in method I was hoping for:

Code: Select all

for k, v in Map("a", 1, "b", 2).rev()
	;

[ntepa]

Here's one way to implement it:

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Map.Prototype.DefineProp "Rev", {
    Call: (m) => (keys:=[m*], f(&k?, &v?) => keys.Length ? (v := m[k:=keys.Pop()], 1) : 0, f)
}

for k, v in Map("a", 1, "b", 2, "c", 3).Rev() {
    OutputDebug k ", " v "`n"
}

[lexikos]

Inverse of what order? As far as I recall, the map enumerator (documentation) does not guarantee any particular order.

[crocodile]

Sorry, I didn't find anything order related in the documentation (but I really checked the documentation carefully).
I tried the following code 1000000 times and got the same order. Can you tell me how to modify this object to break this order?

Code: Select all

	m := Map("a", 1, "b", 2, "c", 3)
	loop 100
		m[A_Index] := A_Index

	st := ""
	for k, v in m
		st .= k ": " v ", "
	st2 := st
	loop 1000000
	{
		st := ""
		for k, v in m
			st .= k ": " v ", "
		if st2 != st
			MsgBox "err> " st

	}
	MsgBox st
; 1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9, 10: 10, 11: 11, 12: 12, 13: 13, 14: 14, 15: 15, 16: 16, 17: 17, 18: 18, 19: 19, 20: 20, 21: 21, 22: 22, 23: 23, 24: 24, 25: 25, 26: 26, 27: 27, 28: 28, 29: 29, 30: 30, 31: 31, 32: 32, 33: 33, 34: 34, 35: 35, 36: 36, 37: 37, 38: 38, 39: 39, 40: 40, 41: 41, 42: 42, 43: 43, 44: 44, 45: 45, 46: 46, 47: 47, 48: 48, 49: 49, 50: 50, 51: 51, 52: 52, 53: 53, 54: 54, 55: 55, 56: 56, 57: 57, 58: 58, 59: 59, 60: 60, 61: 61, 62: 62, 63: 63, 64: 64, 65: 65, 66: 66, 67: 67, 68: 68, 69: 69, 70: 70, 71: 71, 72: 72, 73: 73, 74: 74, 75: 75, 76: 76, 77: 77, 78: 78, 79: 79, 80: 80, 81: 81, 82: 82, 83: 83, 84: 84, 85: 85, 86: 86, 87: 87, 88: 88, 89: 89, 90: 90, 91: 91, 92: 92, 93: 93, 94: 94, 95: 95, 96: 96, 97: 97, 98: 98, 99: 99, 100: 100, a: 1, b: 2, c: 3, 

[boiler]

You seem to be intent on getting someone to state something other than its order is not guaranteed. Don't read any more into it than that.

I tried the following code 1000000 times and got the same order.

Just because you found it to be repeatable (and for the map as created/stored exactly the same way every time) doesn't mean that it would always be so, especially in future builds.

Can you tell me how to modify this object to break this order?

He didn't say there was a way for it to be modified. Its order not being guaranteed is very different than being user-definable.