Call a COM or VB.NET Method with Optional Parameter(s) from C#
Provided by: FMS Development Team
I have to make call to VB.NET or legacy COM components (Interop wrapper will
be created for it.). Fairly often, there are methods with optional
parameters. Unlike VB.NET or VB, C# does not support optional parameter.
Then, how should I call these methods?
C# forces you to specify all the parameters when calling a method. This
means that you have to pass in something for the optional parameter.
You could look into document to figure out the
default value of the parameter and pass it in.
Sometimes, the value you passed in does not matter.
You can pass in a dummy value. Make sure pass in the
right data type.
If the parameter is using the
type "object" (or "variant" from VB/COM standpoint), there is a
shortcut: you can just pass in this value:
If you need do this often, you could define it as a read-only member
variable and use this variable instead, like this:
def = System.Reflection.Missing.Value;
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