[RESOLVED] Two Usages I'm Not Familiar With - Need Explanation

[vb6forever]

1)

Wiadev.Properties!Name.Value

What is the "!" point doing?
If one uses a "." after properties "Name" is not an option

2)

With ![Horizontal Resolution]

The [ ] around variable make it an Escape Name
' If the name used is a reserved word OR Not properly formatted (e.g. has spaces)
' This overrides any deficiencies.

FWIW:
There is a string Const defined as HorizontalResolution {note no space}
So is it finding that string constant and then converting it to an Single ?
However, when I create a dummy variable (tried both Single, and variant) and
assign it to the dummy variable (sngTest = ![Horizontal Resolution], to find its value
I error.

However doing this
sngTest = Wiadev.Items(1).Properties![Horizontal Resolution]
gives me the value contained in the property horizontal resolution.


Explanation Please on usage and how I can obtain the value in [Horizontal Resolution]?

[AAraya]

ChatGPT response

1. Using ! in Wiadev.Properties!Name.Value

The ! operator is used to access members of collections or objects, especially when dealing with dynamic collections like properties or fields in a recordset. Here, Wiadev.Properties!Name.Value is accessing a property called Name within the Properties collection of the Wiadev object.

If you used a dot after Properties (Wiadev.Properties.Name), it would not work because Name is not a direct member of the Properties object but rather a member of the collection held by Properties.

2. Using [] to Escape Names
The [] brackets are used to escape names that are either reserved words or contain characters not typically allowed in identifiers (like spaces).

Explanation of the Code and Usage
With ![Horizontal Resolution]

The [Horizontal Resolution] syntax is used to access a property that has spaces in its name.

[wqweto]

> What is the "!" point doing?

This is the "bang" operator. It's roughly translated from !Key to .Item("Key") i.e. Wiadev.Properties!Name.Value is quivalent to Wiadev.Properties.Item("Name").Value.

Or if I have to be precise obj!Key calls default property with string parameter equal to "Key" i.e. default property might not be Item for certain collections (it can be arbitrarily named).

Extending the above explanation the ![Horizontal Resolution] syntax is just .Item("Horizontal Resolution") i.e. the key as a string contains spaces or other symbols which are not valid for identifiers in the language i.e. can use obj.Item("100km") and obj![100km] but cannot use obj!100km directly as naked 100km is not a valid identifier in VB6 (starts with a digit).

cheers,
</wqw>

[vb6forever]

AAraya and wqweto

THANKS both for taking your time and explanation.

While ChatGPT alludes to it (IMHO), wqweto explanation made it clear (at least to me).
Should of made the connection between DAO "!" and what's going on here. Oh Well!
My original post took care of [].

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FollowOn
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This Wia has me really confused.
This is what I have that works (Dilettante's code)

    Set WiaRootItem = Wiadev.Items(1)      'Root\Top item of the device.
    With WiaRootItem.Properties
         With ![Current Intent]

If one types "Wiadev.Items(1). '{.} note period they can get .Properties.Item
However the Set "WiaRootItem.Properties. '{.} Item does Not comes up
But obviously it is there as ![Current Intent] works

[vb6forever]

I don't recall VB not making this linkage with "Set objects" and/or nested "With", but that may be the issue.

[ahenry]

As you saw, it doesn't have to be named Item:

Or if I have to be precise obj!Key calls default property with string parameter equal to "Key" i.e. default property might not be Item for certain collections (it can be arbitrarily named).

[vb6forever]

ahenry - Thanks for responding.

I picked up on wqweto's (and which you emphasize) quote.
I.e. A string used with a Key, Item, or anything else can be "arbitrarily named".
To my knowledge this has always been the case.
I.e. obj! uses the Default for whatever.

The above is DAO comparable to:

!fldMem versus .Fields(fldMemo)

=====================
1)
=======================
From what I can tell, in using this format, the object browser DOES NOT recognize it.
So its a PITA, as you don't know where your at in the tree.

So how one navigates between {dot} usage versus {bang} usage EASILY is the question?

=======================
2)
=======================
While I get the usage of ![Horizontal Resolution] and the fact [Horizontal Resolution] is
in effect, a string without blanks, where my confusion is coming in, is that the [Horizontal Resolution]string represents a Const ((WIA_IPS_XRES)), BUT no Const with that name is defined
anywhere in the program (i can find).

So when an value assignment is made to:
![Horizontal Resolution].Value = 300

which is really:
![6147].Value = 300

VB5/6 (to my knowledge) does not bring in a header file like C/C++.
If it has that ability (unknown to me), I could not find one in the VBP file or elsewhere.

How does the system (compiler) know that this string is 6147 (WIA_IPS_XRES), since [Horizontal Resolution] is NOT defined anywhere as Const [Horizontal Resolution] = 6147?

[VanGoghGaming]

However doing this
sngTest = Wiadev.Items(1).Properties![Horizontal Resolution]
gives me the value contained in the property horizontal resolution.

Explanation Please on usage and how I can obtain the value in [Horizontal Resolution]?

[Horizontal Resolution] is not a constant, it's the Name of a Property. You can enumerate all properties to see what they are:

Dim Prop As Property
For Each Prop In Wiadev.Items(1).Properties
    Debug.Print Prop.Name, Prop.Value
Next Prop

It should print "Horizontal Resolution" among the list of other properties. This "!" bang operator is just a syntax shortcut. If it adds to your confusion then don't use it.

[vb6forever]

VanGoghGaming: Thanks for responding.

This "!" bang operator is just a syntax shortcut. If it adds to your confusion then don't use it.

I agree. But doing some testing this AM, I've narrowed down where my confusion is coming from.

1) Initially I thought the PropertyId is the item index. But that appears NOT to be the case.

This Fails where the PropertyID for [Horizontal Resolution] = 6147

Dim a As Long
Wiadev.Items(1).Properties.Item(6147).Value = 150
a = Wiadev.Items(1).Properties.Item(6147).Value
Debug.Print Wiadev.Items(1).Properties.Item(6147).Value

Using Item and the Name for the Item as the Index (ignoring Bang usage, works)
I get Bang is taking the place of Item

This Works!

Dim s As String
s = "Horizontal Resolution"

Wiadev.Items(1).Properties.Item([s]).Value = 150
a = Wiadev.Items(1).Properties.Item(s).Value
Debug.Print Wiadev.Items(1).Properties.Item(s).Value

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Question
----------
So what is the PropertyID used for (if anything), and how does one use it with Wia?

HOW DUMB can I be!!
The Item Index needs to be a string.
So the PropertyID works if the Item Index is made a string.

'This Works

Dim s As String
s = "6147"
   
Wiadev.Items(1).Properties.Item(s).Value = 150
Debug.Print Wiadev.Items(1).Properties.Item(s).Value
a = Wiadev.Items(1).Properties.Item(s).Value