c# - Is it necessary to throw a NullReferenceException from an extension method? -

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• argumentnullexception or nullreferenceexception extension method? 5 answers

if define extension method such this:

static public string totitlecase(this string instance, cultureinfo culture) {     if (instance == null)         throw new nullreferenceexception();      if (culture == null)         throw new argumentnullexception("culture");      return culture.textinfo.totitlecase(instance); } 

is necessary me check string instance null , throw null reference exception myself? or clr treat extension methods instance methods in case , handle checking/throwing me?

i know extension methods syntactic sugar static methods, perhaps c# compiler adds in check @ compile time? please clarify :)

no. should never throw nullreferenceexception manually. should ever thrown framework itself.

in context, should throwing argumentnullexception both instance , culture:

static public string totitlecase(this string instance, cultureinfo culture) {     if (instance == null)         throw new argumentnullexception("instance");      if (culture == null)         throw new argumentnullexception("culture");     return culture.textinfo.totitlecase(instance); } 

from nullreferenceexception documentation:

note applications throw argumentnullexception exception rather nullreferenceexception exception discussed here.