Is expression exist

[Ehaviv]

Hi

Currently I check if an expression
exist by using:

Try
expression.rename
Catch
' expression already exists
End Try

Please if someone know of a more
normal way.

Thank you.

 

[cowski]

I'm not sure if this is what you'd call 'normal', but I use a try catch block to create the expression. If it already exists, a specific error code will be returned - at which point I just use the existing expression. Something like below:

Dim exp_1 As Expression = Nothing
Dim exp1Value As Double = 2.7182
Try
    'create expression, type: Number [constant] (unitless)
    '.Create method will not work to create an expression of type String
    exp_1 = workPart.Expressions.Create("NXJ_1 = " & exp1Value.ToString)
 
    'alternately, let the compiler convert the value to a string
    'exp_1 = workPart.Expressions.Create("NXJ_1 = " & exp1Value)
 
    'or, pass in the value directly
    'exp_1 = workPart.Expressions.Create("NXJ_1 = 2.7182")
 
Catch ex As NXException
[highlight #FCE94F]    If ex.ErrorCode = 1050017 Then
        'expression already exists[/highlight]
        exp_1 = workPart.Expressions.FindObject("NXJ_1")
    Else
        'other error
        lw.WriteLine("NX exception: " & ex.ErrorCode & ", " & ex.Message)
 
    End If
 
End Try

Alternatively, you could iterate through the expression collection and check to see if an expression with a particular name already exists.

www.nxjournaling.com

 

[Ehaviv]

Cowski thank you.

The yellow code is more correct then
check an array.
Because is unsafe.

I wonder why nx developers
Don't provide a direct statement
Something lik isexprexisy.

Thank you again.

 

[cowski]

The yellow code is more correct then
check an array.
Because is unsafe.

What do you deem to be 'unsafe' about iterating through a collection or array?

www.nxjournaling.com

 

[Ehaviv]

I mean that expressions are created
Dynamically and can be a situation
that the array expressions are
not updated.

Thank you.