C# Declare Variable in if statement, Common Base Class

Question

I am attempting to pass a string into a method and based on what string is passed in, either instantiate BasicHttpBinding or WSHttpBinding. The following if statement is in my code.

if(bindingObject == "basic")
{System.ServiceModel.BasicHttpBinding binding = new System.ServiceModel.BasicHttpBinding();}
else
{System.ServiceModel.WSHttpBinding binding = new System.ServiceModel.WSHttpBinding();

This code gives me the error

The name 'binding' does not exist in the current context

From my research it seems I have to use a common base class between the two service models if I want to use the variable named binding no matter which ServiceModel I need to use.

My question is, what is the common base class that would work? Or is there a way to do this. The closest I have found is System.ServiceModel.Channels.Binding but then I get the error such as

does not contain a definition for 'MaxBufferPoolSize' and no extension method 'MaxBufferPoolSize' accepting a first argument of tyep 'System.ServiceModel.Channels.Binding' could be found

Answer 1

The problem you're facing is because of scoping of local variables. According to C# specs for scoping from MSDN,

Scopes can be nested, and an inner scope may redeclare the meaning of a name from an outer scope (this does not, however, remove the restriction imposed by §1.20 that within a nested block it is not possible to declare a local variable with the same name as a local variable in an enclosing block).

Another from spec for identifiers scoping,

For each occurrence of a given identifier as a simple-name in an expression or declarator, within the local variable declaration space, immediately enclosing block, or switch-block of that occurrence, every other occurrence of the same identifier as a simple-name in an expression or declarator within the immediately enclosing block or switch-block must refer to the same entity. This rule ensures that the meaning of a name is always the same within a given block, switch block, for-, foreach- or using-statement, or anonymous function.

Now moving to the error you're facing: BasicHttpBinding is derived from HttpBindingBase which derived from Binding and implement IBindingRuntimePreferences. WSHttpBinding is dervied from WSHttpBindingBase which derived from Binding and implement IBindingRuntimePreferences.

But the property MaxBufferPoolSize resides in HttpBindingBase and WsHttpBindingBase and not in their common parent Binding or IBindingRuntimePreferences. Which means you can not use a common class to represent these bindings. Rather you should use dynamic as type which would bind the types at runtime instead of compile time.

Public dynamic GetBinding(string bindingObject)
 {
    if (bindingObject == "basic")
    {
        binding = new System.ServiceModel.BasicHttpBinding();
    }
    else
    {
        binding = new System.ServiceModel.WSHttpBinding();
    }

   return binding;
  }