Method chaining with short-circuit parameter evaluation
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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 == nullthen we have a runtime null ref error because, regardless of what the NotNull method returns as part of the chaining,myObjectis still null. So this got me thinking: You can doif (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
No Programming Questions in the lounge. I am going to have to report you to yourself. Please give yourself a good dressing down and wag an admonishing finger at yourself!
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
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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 == nullthen we have a runtime null ref error because, regardless of what the NotNull method returns as part of the chaining,myObjectis still null. So this got me thinking: You can doif (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
Oooh! Oooh! Oooh! Use
ON ERROR RESUME! :-D -
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 == nullthen we have a runtime null ref error because, regardless of what the NotNull method returns as part of the chaining,myObjectis still null. So this got me thinking: You can doif (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
Chris Maunder wrote:
Am I procrastinating?
Yes.
Nihil obstat
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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 == nullthen we have a runtime null ref error because, regardless of what the NotNull method returns as part of the chaining,myObjectis still null. So this got me thinking: You can doif (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
For years I wished for something like
Flibber f = Bugger?.GetGoodShoboil()?.Libbl;to evaluate to null silently if either Bugger is or GetGoodShoboil Returns null. I dimly remember last time I voiced this here, I was told to not want this by the disciples of the Occasionally Useful Suggestion Of Demeter[^], as well as an apparently unrelated Sir Or Madam Chris Munder who suggested to not add more garbage to this wonderful, sleek new thing called C#. -
No Programming Questions in the lounge. I am going to have to report you to yourself. Please give yourself a good dressing down and wag an admonishing finger at yourself!
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
I would if it were a programming question. And, regardless of the attempt at humour, I am sad, deeply sad, that it was you who jumped on the "no programming questions" bandwagon. So I'm going to jump on my soapbox because it's a fantastic way to procrastinate further, and bemoan the lack of interesting technical discussion on the lounge where bad jokes and political rhetoric seem to be more accepted than discussion on the topics that we as developers hold dearest to our hearts. For shame, David. For shame.
cheers, Chris Maunder The Code Project | Co-founder Microsoft C++ MVP
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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 == nullthen we have a runtime null ref error because, regardless of what the NotNull method returns as part of the chaining,myObjectis still null. So this got me thinking: You can doif (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
Chris Maunder wrote:
Am I procrastinating?
I think this would get my vote...
Beauty is in the eye of the beer-holder Be careful which toes you step on today, they might be connected to the foot that kicks your butt tomorrow. You can't scare me, I have children.
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For years I wished for something like
Flibber f = Bugger?.GetGoodShoboil()?.Libbl;to evaluate to null silently if either Bugger is or GetGoodShoboil Returns null. I dimly remember last time I voiced this here, I was told to not want this by the disciples of the Occasionally Useful Suggestion Of Demeter[^], as well as an apparently unrelated Sir Or Madam Chris Munder who suggested to not add more garbage to this wonderful, sleek new thing called C#.I was drunk. That suggestion is awesome and I recant.
cheers, Chris Maunder The Code Project | Co-founder Microsoft C++ MVP
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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 == nullthen we have a runtime null ref error because, regardless of what the NotNull method returns as part of the chaining,myObjectis still null. So this got me thinking: You can doif (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
You can implement this using extension methods[^] ...
Espen Harlinn Principal Architect, Software - Goodtech Projects & Services AS Projects promoting programming in "natural language" are intrinsically doomed to fail. Edsger W.Dijkstra
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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 == nullthen we have a runtime null ref error because, regardless of what the NotNull method returns as part of the chaining,myObjectis still null. So this got me thinking: You can doif (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
Interesting. Today, you'd have to wrap it in a Try/Catch and eat the null reference exception if thrown. But, if you could do this, you would have to be able to tell the compiler you don't want the exception thrown and to just continue with the next statement. Hell, they added async/await keywords, why not add another one? I'm kind of thinking that this would complicate debugging a bit too.
A guide to posting questions on CodeProject[^]
Dave Kreskowiak -
I would if it were a programming question. And, regardless of the attempt at humour, I am sad, deeply sad, that it was you who jumped on the "no programming questions" bandwagon. So I'm going to jump on my soapbox because it's a fantastic way to procrastinate further, and bemoan the lack of interesting technical discussion on the lounge where bad jokes and political rhetoric seem to be more accepted than discussion on the topics that we as developers hold dearest to our hearts. For shame, David. For shame.
cheers, Chris Maunder The Code Project | Co-founder Microsoft C++ MVP
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I would if it were a programming question. And, regardless of the attempt at humour, I am sad, deeply sad, that it was you who jumped on the "no programming questions" bandwagon. So I'm going to jump on my soapbox because it's a fantastic way to procrastinate further, and bemoan the lack of interesting technical discussion on the lounge where bad jokes and political rhetoric seem to be more accepted than discussion on the topics that we as developers hold dearest to our hearts. For shame, David. For shame.
cheers, Chris Maunder The Code Project | Co-founder Microsoft C++ MVP
Do Not Procrastinate Today! Wait until tomorrow and have a whole day of it. Until then, stare at this picture[^] of a cat.
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
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I was drunk. That suggestion is awesome and I recant.
cheers, Chris Maunder The Code Project | Co-founder Microsoft C++ MVP
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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 == nullthen we have a runtime null ref error because, regardless of what the NotNull method returns as part of the chaining,myObjectis still null. So this got me thinking: You can doif (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
The null object pattern.
public class Customer{}
public class NullCustomer : Customer{}Then instead of assigning a customer reference to null you assign it to the null customer, etc. Then you can do all of your work without null checks. There are some instances where this works really, really, well. However, if you are chaining functions it is probably some sort of workflow so there maybe another solution that issue.
Need custom software developed? I do custom programming based primarily on MS tools with an emphasis on C# development and consulting. "And they, since they Were not the one dead, turned to their affairs" -- Robert Frost "All users always want Excel" --Ennis Lynch
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No. I always say that.
Panic, Chaos, Destruction. My work here is done. Drink. Get drunk. Fall over - P O'H OK, I will win to day or my name isn't Ethel Crudacre! - DD Ethel Crudacre I cannot live by bread alone. Bacon and ketchup are needed as well. - Trollslayer Have a bit more patience with newbies. Of course some of them act dumb - they're often *students*, for heaven's sake - Terry Pratchett
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I would if it were a programming question. And, regardless of the attempt at humour, I am sad, deeply sad, that it was you who jumped on the "no programming questions" bandwagon. So I'm going to jump on my soapbox because it's a fantastic way to procrastinate further, and bemoan the lack of interesting technical discussion on the lounge where bad jokes and political rhetoric seem to be more accepted than discussion on the topics that we as developers hold dearest to our hearts. For shame, David. For shame.
cheers, Chris Maunder The Code Project | Co-founder Microsoft C++ MVP
I think you should ban him! :laugh: ;P
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No. I always say that.
Panic, Chaos, Destruction. My work here is done. Drink. Get drunk. Fall over - P O'H OK, I will win to day or my name isn't Ethel Crudacre! - DD Ethel Crudacre I cannot live by bread alone. Bacon and ketchup are needed as well. - Trollslayer Have a bit more patience with newbies. Of course some of them act dumb - they're often *students*, for heaven's sake - Terry Pratchett
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I may well be tonight.
Panic, Chaos, Destruction. My work here is done. Drink. Get drunk. Fall over - P O'H OK, I will win to day or my name isn't Ethel Crudacre! - DD Ethel Crudacre I cannot live by bread alone. Bacon and ketchup are needed as well. - Trollslayer Have a bit more patience with newbies. Of course some of them act dumb - they're often *students*, for heaven's sake - Terry Pratchett
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If voting was available, I would of shot you a 5, but alas.....
Software Kinetics - Dependable Software news
Norm .net wrote:
If voting was available, I would of shot you a 5, but alas.....
Seconded.
CPallini wrote:
You cannot argue with agile people so just take the extreme approach and shoot him. :Smile:
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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 == nullthen we have a runtime null ref error because, regardless of what the NotNull method returns as part of the chaining,myObjectis still null. So this got me thinking: You can doif (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
There is a way that you could do this, but it would be much more trouble than it was worth, and it would definitely open up a whole world of hurt. Effectively, what would need to be implemented is an IL rewriter to manage and rewrite the chain internally. Then you could create a fluid interface that would need to be recognised as the item that needs rewriting.
*pre-emptive celebratory nipple tassle jiggle* - Sean Ewington
"Mind bleach! Send me mind bleach!" - Nagy Vilmos
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