Adding arrays working suspiciously

[monoceres]

This doesn't seem right to me:

#include <array.au3>
Local $a[2]=[1,2]
Local $a2[2]=[2,3]
Local $a3=$a+$a2
_ArrayDisplay($a3)

Output is [1,2]. Optional output would be the combination of the two arrays, but if that's out of the question, maybe throw an error or something?

[Nutster]

I will investigate. Did you check @Error after the line that tried to add them?

#include <array.au3>
Local $a[2]=[1,2]
Local $a2[2]=[2,3]
Local $a3=$a+$a2
$error = @Error
If $Error > 0 Then 
    Msgbox(0, "Error!", "Error set to " & $Error)
Else
    _ArrayDisplay($a3)
Endif

[Jon]

It's not working because adding arrays is undefined. It actually does nothing atm. $a1 + a2 just leaves you with $a1.

If such a feature were implemented, I'm not even sure what the result should be...

[anonymous]

I think that [1,2,2,3] would be the most logical output in the example.

[Valik]

I could argue that [3,4] should be the output.

[Gabriel13]

I don't think you'd want the "+" operator to work either way with arrays.

For array concatenation, if anything the "&" operator should be borrowed instead, to be consistent with the string concatenation operator already present in AutoIt. [1,2] & [2,3] == [1,2,2,3] would make a lot more sense than trying to use the "+" operator - though using "&" would introduce concatenation ambiguity. What if a string and array are concatenated?

As for non-atomic math operations, that would open the door to all sorts of complex problems. I used to work with a language called Euphoria (​http://rapideuphoria.com/), which allows for similar non-atomic math and boolean operations. One casualty of this feature was the inability to consistently implement short-circuit boolean evaluation, since the result could potentially be an array of values.

Aside from that, the implementation could easily become quite complex. Would [1,2] + [2,[3,4]] be allowed? If so, how about 3 + [1,[2,3,[4,5]]]? or [4,5] + 6,7],[8,[9,10?]? What if COM objects or other non-numeric data types are contained somewhere within the arrays? And what happens when arrays of differing lengths are involved, such as [1,2] + [3,4,5]?

It's probably simpler and less confusing to simply throw an error whenever arrays are involved in binary math, boolean or concatenation operations.

[Valik]

Since this is not a bug I'm changing it to a feature request.

[Nutster]

There are too many ways to implement array mathematics. Use UDF's to perform a specific operation, such as matrix addition or matrix multiplication vs. array concatenation or polynomial multiplication. Each is different and each yields different types of result.

Not going to happen. Rejected.