When I was working on the .NET reflection extravaganza thing that I explained in my previous column, i learnt one another interesting thing, that is about the Type.InvokeMember. How will pass out or ref parameters for the method invoked using Type.InvokeMember ? If you are going to invoke a method with the prototype
int DoSomething(string someString, int someInt);
then you would use InvokeMember like this:-
object obj = someType.InvokeMember(“DoSomething”,
BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance,
null,
this,
new object[] {“Largest Integer”, 1});
or use some variables in the new object[] {…}. But what do you with the args if DoSomething takes out or ref parameters ?
int DoSomething(out string someString, ref int someInt);
Something like this will not work
string someText = string.Empty;
int someInt = 0;
object obj =
someType.InvokeMember(
“DoSomething”,
BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance,
null,
this,
new object[] {someText, someInt}
);
It is tricky.
object[] args = new object[] { someText, someInt };
object obj =
someType.InvokeMember(
“DoSomething”,
BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance,
null,
this,
args
);
or even suprisingly this works:-
object[] args = new object[2];
// or object[] args = new object[] { null, null };
object obj =
someType.InvokeMember(
“DoSomething”,
BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance,
null,
this,
args
);
Access the values by indexing args. So declaring the argument object[] as a local variable solves the problem, but I do not understand why this behavior. May be somebody can explain !!!
