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GeneralMethod chaining with short-circuit parameter evaluation [modified]adminChris Maunder10 Jan '13 - 3:53 
I am testing several depths of properties in an object to make sure they are safe before I call them:
Test.NotNull(myObject);
if (myObject != null)
{
    Test.NotNull(myObject.MyProperty);
    if (myObject.MyProperty != null)
        Test.IsPositive(myObject.MyProperty.Id);
        ...
}
I was thinking it would be really cool to be able to do
Test.NotNull(myObject).NotNull(myObject.MyProperty).IsPositive(myObject.MyProperty.Id);
but obviously if myObject == null then we have a runtime null ref error because, regardless of what the NotNull method returns as part of the chaining, myObject is still null.
 
So this got me thinking: You can do
if (myObject != null && myObject.MyProperty != null)
because of short circuit boolean evaluation in C#, but I was wondering, with my fairly mainstream experience in languages, if there are languages out there that would allow chaining of methods with short circuit evaluation.
 
Essentially you'd have to have the input parameter be resolved after the method was called in order to have the method be able to say "I don't need the input parameter, please just ignore it".
 
Has anyone heard of this? Would it open up a World Of Pain when it comes to debugging? Would it be useful? Am I procrastinating?
 
---
Update: and it turns out this leads into a great discussion of extension methods. See
The Maybe Monad[^] and Chained null checks and the Maybe monad[^] for two ways of achieving this. Once you've done that, debate the correctness of extension methods that are able by design to operate on a null references.
 
I will be over there looking for new, shiny, distracting things.
cheers,
Chris Maunder
 
The Code Project | Co-founder
Microsoft C++ MVP


modified 10 Jan '13 - 16:48.
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GeneralRe: Method chaining with short-circuit parameter evaluationmemberDalek Dave10 Jan '13 - 4:00 
GeneralRe: Method chaining with short-circuit parameter evaluationadminChris Maunder10 Jan '13 - 4:07 
GeneralRe: Method chaining with short-circuit parameter evaluationgroupNorm .net10 Jan '13 - 4:14 
GeneralRe: Method chaining with short-circuit parameter evaluationmember Shelby Robertson 10 Jan '13 - 4:41 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberPaul Conrad10 Jan '13 - 6:06 
GeneralRe: Method chaining with short-circuit parameter evaluationgroupNorm .net10 Jan '13 - 20:20 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberDalek Dave10 Jan '13 - 4:18 
JokeRe: Method chaining with short-circuit parameter evaluationmemberdjj5510 Jan '13 - 4:34 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberPIEBALDconsult10 Jan '13 - 4:01 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberMaximilien10 Jan '13 - 4:03 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberpeterchen10 Jan '13 - 4:06 
GeneralRe: Method chaining with short-circuit parameter evaluationadminChris Maunder10 Jan '13 - 4:08 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberpeterchen10 Jan '13 - 4:20 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberDalek Dave10 Jan '13 - 4:26 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberNagy Vilmos10 Jan '13 - 4:34 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberDalek Dave10 Jan '13 - 4:37 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberNagy Vilmos10 Jan '13 - 4:40 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberjibesh10 Jan '13 - 5:03 
GeneralRe: Method chaining with short-circuit parameter evaluationmembergavindon10 Jan '13 - 4:08 
GeneralRe: Method chaining with short-circuit parameter evaluationmvpEspen Harlinn10 Jan '13 - 4:11 
GeneralRe: Method chaining with short-circuit parameter evaluationmvpEddy Vluggen10 Jan '13 - 4:53 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberJörgen Andersson10 Jan '13 - 8:42 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberRanjan.D10 Jan '13 - 5:01 
GeneralRe: Method chaining with short-circuit parameter evaluationmvpDave Kreskowiak10 Jan '13 - 4:13 
GeneralThere is a cool patternmemberEnnis Ray Lynch, Jr.10 Jan '13 - 4:22 
GeneralRe: Method chaining with short-circuit parameter evaluationprotectorPete O'Hanlon10 Jan '13 - 4:43 
GeneralRe: Method chaining with short-circuit parameter evaluationadminChris Maunder10 Jan '13 - 10:53 
GeneralRe: Method chaining with short-circuit parameter evaluationprotectorPete O'Hanlon10 Jan '13 - 10:58 
GeneralRe: Method chaining with short-circuit parameter evaluationmembermark merrens10 Jan '13 - 4:54 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberRoger Wright10 Jan '13 - 5:02 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberNemanja Trifunovic10 Jan '13 - 5:11 
GeneralRe: Method chaining with short-circuit parameter evaluationadminChris Maunder10 Jan '13 - 10:54 
GeneralRe: Method chaining with short-circuit parameter evaluationprotectorAspDotNetDev10 Jan '13 - 5:15 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberszukuro10 Jan '13 - 5:21 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberszukuro10 Jan '13 - 5:18 
GeneralRe: Method chaining with short-circuit parameter evaluationmemberZac Greve10 Jan '13 - 5:41 
GeneralRe: Method chaining with short-circuit parameter evaluationmvpOriginalGriff10 Jan '13 - 5:19 
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