For $oElement In $oElements: help me understand

[DanielTyrkiel]

Hi,

I'm trying to understand how does this work:

; *******************************************************
; Example 1 - Open a browser with the basic example, get the collection
; of all elements and display the tagname and innerText of each
; *******************************************************

#include <IE.au3>

Local $oIE = _IE_Example("basic")
Local $oElements = _IETagNameAllGetCollection($oIE)
For $oElement In $oElements
MsgBox(0, "Element Info", "Tagname: " & $oElement.tagname & @CR & "innerText: " & $oElement.innerText)
Next

in the "For" loop there is a variable "$oElement" but I can't see it defined anywhere.

I don't understand how it works.

I have searched the web, this forum, autoit help file and even the IE UDF, but can't find a clear answer.

Sorry if it's an easy one, but I can't use it if I don't understand it.

regards

Daniel

[BrewManNH]

Did you look in the help file for the For...In function?

The Variable will be created automatically with a Local scope, even when MustDeclareVars is on.

If the expression is an Object collection with no elements, or an multi-dimensional array, the loop will be skipped and the Variable will contain an empty string.

If the expression is not an Object nor an Array, the script stops with an error, unless a COM Error handler had been configured.

AutoIt Arrays are read-only when using For...In. While you can assign the variable inside the For...In loop a value, this change is not reflected in the array itself. To modify the contents of an array during enumeration, use a For...To loop.

[DanielTyrkiel]

I've just read this: The Variable will be created automatically with a Local scope, even when MustDeclareVars is on.

So it's declared by the loop statement itself...

The statement operates on colections or arrays so it must recognise them somehow.

I think I'm getting it.

_IETagNameAllGetCollection retrieves a collection of sorts and the variable defined between "for" and "in" is used to pass

elements of the colection one by one.

Have I got it?

[BrewManNH]

Yes, that's it in a nutshell. If you have an array, or in your case a collection, it will loop through the elements. The variable name will contain the contents of each one of the elements of the array/object collection as it loops through it. So it would work like this.

Global $Array[3] = ["Boy", "Dog", "Cat"]
For $Elements In $Array
    ConsoleWrite("$Elements = " & $Elements & @CRLF)
Next

If you run that in SciTE you'll see what the variable $Elements contains each time through the loop.

[DanielTyrkiel]

Cool, I ran it. Got it now. I didn't realise that this function assigned its own variable on the fly.

I've been learning to read the descriptions of functions a bit closer and noticing the fine differences.

Many thanks!