Can I pass a property to a method?

General
1

I’d like to have a method with parameters called alteredproperty as string, myvalue as boolean (for example)

This would then be called like :-

mymethodwithparameter(“Visible”,False)

and then the method would do something like (which doesn’t work as I’ve put it here)

someobjectonwindow.alteredproperty.stringvalue=myvalue

Obviously, the above is more like pseudocode but hopefully someone will understand what I mean/want!

Thanks.

2

If you aren’t concerned about performance you can do this via Introspection.

I’ve just hacked the following together that should do what you want:

[code]Sub SetPropertyValue(pObject As Object, pPropertyName As String, pValue As Variant)
Dim found As Boolean
Dim typeInfoObj As Introspection.TypeInfo
Dim propertyInfoObjList(-1) As Introspection.PropertyInfo
Dim count, i As Int32
Dim thePropertyInfoObj As Introspection.PropertyInfo

found = False

typeInfoObj = Introspection.GetType(pObject)

propertyInfoObjList = typeInfoObj.GetProperties

count = UBound(propertyInfoObjList)
For i = 0 To count
thePropertyInfoObj = propertyInfoObjList(i)

If thePropertyInfoObj.Name = pPropertyName Then
  thePropertyInfoObj.Value(pObject) = pValue
  
  found = True
  
  Exit For
End If

Next

If found = False Then
Raise New KeyNotFoundException
End If
End Sub[/code]

Example:
Set the Title property for a window:

SetPropertyValue(Self, "Title", "Hello")

Edit…

To make this a bit more friendlier, put the method into a module and change the declaration:

Extends pObject As Object, pPropertyName As String, Assigns pValue As Variant

Examples of setting properties on a window:

Self.SetPropertyValue("Title") = "Hello" Self.SetPropertyValue("Width") = 100

4

I have a feature request out there for something like GetTypeInfo( object.Property ) As PropertyInfo.

5

[quote=463224:@Michel Bujardet]Create a method with parameters alteredproperty as string, myvalue as boolean, that’s it.

Does that answer your question ?[/quote]

No because that’s just the start of my explanation of what I want. I want to pass those method parameters (which yes, I do know how to use) and use them with object properties as per my question.

6

Wow Kevin, thank you for your detailed post and the time to write that code.

Is performance in a desktop app doing this likely to pose a real world problem then?

[quote=463216:@Kevin Gale]If you aren’t concerned about performance you can do this via Introspection.

I’ve just hacked the following together that should do what you want:

[code]Sub SetPropertyValue(pObject As Object, pPropertyName As String, pValue As Variant)
Dim found As Boolean
Dim typeInfoObj As Introspection.TypeInfo
Dim propertyInfoObjList(-1) As Introspection.PropertyInfo
Dim count, i As Int32
Dim thePropertyInfoObj As Introspection.PropertyInfo

found = False

typeInfoObj = Introspection.GetType(pObject)

propertyInfoObjList = typeInfoObj.GetProperties

count = UBound(propertyInfoObjList)
For i = 0 To count
thePropertyInfoObj = propertyInfoObjList(i)

If thePropertyInfoObj.Name = pPropertyName Then
  thePropertyInfoObj.Value(pObject) = pValue
  
  found = True
  
  Exit For
End If

Next

If found = False Then
Raise New KeyNotFoundException
End If
End Sub[/code]

Example:
Set the Title property for a window:

SetPropertyValue(Self, "Title", "Hello")

Edit…

To make this a bit more friendlier, put the method into a module and change the declaration:

Extends pObject As Object, pPropertyName As String, Assigns pValue As Variant

Examples of setting properties on a window:

Self.SetPropertyValue("Title") = "Hello" Self.SetPropertyValue("Width") = 100[/quote]

7

[quote=463237:@Rod Pascoe]Wow Kevin, thank you for your detailed post and the time to write that code.

Is performance in a desktop app doing this likely to pose a real world problem then?[/quote]
Introspection is definitely considered “expensive” and “slow” but honestly in most cases that expense is negligible. Unless you’re doing a heavy computing math application or image processing, I doubt the cost will be impactful. I use a ton of introspection to serialize and deserialize objects, and it works great. Think of it as a scale where bitwise operations are extremely fast, operations on primitives are fast, dealing with objects and method calling is slow, and introspection/reflection is even slower. But you can still do 1000’s of introspection calls within a second without a user noticing any problem.

8

[quote=463237:@Rod Pascoe]Wow Kevin, thank you for your detailed post and the time to write that code.

Is performance in a desktop app doing this likely to pose a real world problem then?[/quote]
I haven’t benchmarked the code but I probably wouldn’t want to call it lots of times within a loop.

9

Thanks Brock.

10

Thanks Kevin,

I’ll only be using it a handful of times for what I have in mind and those should be several minutes apart so all good.

Nice to know though, always good to learn.