How to Handle Nulls Passed to Extension Methods
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From: Jehu Galeahsa on 10 May 2010 23:25 Hello: What is the correct/typical way to handle null "this" arguments passed to an extension method? Thanks, Travis Parks
From: Tom Shelton on 10 May 2010 23:52 It happens that Jehu Galeahsa formulated : > Hello: > > What is the correct/typical way to handle null "this" arguments passed > to an extension method? > > Thanks, > Travis Parks Well, for consistancy, I generally throw a null reference exception - just like any other instance method would do if called on a jull reference exception. -- Tom Shelton
From: Peter Duniho on 11 May 2010 03:14 Jehu Galeahsa wrote: > Hello: > > What is the correct/typical way to handle null "this" arguments passed > to an extension method? It depends on what the method does and whether a null "this" makes any sense. IMHO, you should try to avoid a design where calling a method on a null "this" makes any sense. And following that philosophy, you should throw a NullReferenceException if the "this" argument is null (I prefer that over ArgumentNullException for the "this" in an extension method, especially since it comes for free most of the time :) ). But I can't rule out some exceptional case where an operation on "null" makes sense. In that case, you would not throw the exception. Pete
From: Patrice on 11 May 2010 04:58 Hello, > What is the correct/typical way to handle null "this" arguments passed > to an extension method? I would throw the same exception than when you try to call a method using a null instance as this is the intended usage... -- Patrice
From: Arne Vajhøj on 11 May 2010 19:44
On 10-05-2010 23:25, Jehu Galeahsa wrote: > What is the correct/typical way to handle null "this" arguments passed > to an extension method? I would not handle it. Meaning that I think you should write the code without any special test for it and let it cause whatever exception or not it may. I don't see extension methods as having responsibility for enforcing any contracts in this regard, because it is really a utility method. Arne |