Test if an object property exists without error trapping

[Jubinell]

Hi,

Sometimes in VBA it's necessary to make sure that the property of an object exists before attempting to apply code to it.

For example, I'd like to set the chart title to "Awesome Chart" regardless of whether the chart already has a title or not.

Sub Add Chart()
Dim C As Chart
 For Each c In ThisWorkbook.Charts
    c.ChartTitle.Characters.Text = "5"
End If
End Sub

However if the chart doesn't have a title the c.charttitle.characters will fail. How do I test to see if .Characters exist before calling its .text property?

I know I can do On Error Goto, but that seems like a back-door approach to a front-door problem.

 

[tusharm]

On some occasions you will find a complementary property that you can check. For example, in the case of a chart title, use HasTitle.

That said, there's nothing "back door" about using error handling. In fact, as far as I am concerned, it is the most straight forward way of dealing with complex objects in complex environments. Imagine how compext the object model would become if the object designers had to provide a non-error-trap way to check which of the hundreds (or thousands) of properties and methods were valid at any given time.

 

[Jubinell]

That makes sense. Thank you.

 

[tusharm]

You are welcome.

 

[Caltor]

On some occasions you will find a complementary property that you can check. For example, in the case of a chart title, use HasTitle.

That said, there's nothing "back door" about using error handling. In fact, as far as I am concerned, it is the most straight forward way of dealing with complex objects in complex environments. Imagine how compext the object model would become if the object designers had to provide a non-error-trap way to check which of the hundreds (or thousands) of properties and methods were valid at any given time.

I would respectfully disagree and say that using Error Handling is a hokey way of checking for the existance of a property and reflects a shortcoming in the VBA language. You could try FreeVBCode code snippet: PropertyExists Routine Using TLBINF32.DLL for a way of doing it though.