Tuesday, May 27, 2008

ReSharper 3.1 and Empty Constructor

ReSharper has this nice feature to make you aware of code that are not necessarily required. I like this feature since it allows me to reduce the number of characters that I have to read and as a consequence I can process more of them at a time. As a result I can work faster. However, I just came across an item where this feature doesn't work as I hoped. I have a class publicly visible from outside the assembly. For the constructor I have added a number of XML documentation tags. The constructor itself doesn't take parameters and it doesn't do anything. But I want to keep the constructor for the XML documentation. Since the compiler automatically generates the same constructor, ReSharper emits that as a warning and also suggests to remove the constructor. If I followed that suggestion it would also remove the XML documentation along with it. Alternatively ReSharper offers to supress the warning. So I did that. ReSharper is now happy. But my compiler isn't since it sees the following (the pragma was added by ReSharper):
#pragma warning disable EmptyConstructor
The compiler now complains about 'EmptyConstrutor' not being a valid number. Fair enough it is not. So I removed the pragma since any other pragma would get ReSharper complaining again. To keep ReSharper quiet the constructor now looks as follows:
public class Foo() {
  // ... the XML markup for documentation
  public Foo() {
    ; // to shut up ReSharper
Now both, the compiler and ReSharper, are happy! :-) No big issue but the better solution would have been if ReSharper would modify the code only in such a way that it doesn't cause additional warnings. Update This applies to essentially all such pragma's ReSharper inserts, including but not limited to:
  • UnusedMemberInPrivateClass
  • PossibleNullReferenceException

As stated before: Best option would be if the code inserted by ReSharper would not cause additional warnings from the C# compiler. Or in other words: The added code should be "compatible" with the compiler. One option could be to use comments instead. The compiler ignores them.

The C# preprocessor is not as powerful and flexible as the C/C++ one. The latter allows your extensions by ignoring unknown ones. The C# version does not have that "back door" but checks them for validity as well. In essence you can't define your own. (Or at least you shouldn't if you don't want to cause compiler warnings.)


Serge Baltic said...

Seems like this warning is a bug in the csc compiler, as the pragma is not required to be a number by the standard. So it's pretty safe to suppress the compiler warning in the project settings by its number (and that's what we'd do).

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