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Is it unreasonable to expect Any() *not* to throw a null reference exception?
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When you create an extension method you can, of course, call it on null.But, unlike an instance method call, calling it on null doesn't have to throw a NullReferenceException -> you have to check and throw it manually.
For the implementation of the Linq extension method Any() Microsoft decided that they should throw a NullReferenceException (https://github.com/dotnet/corefx/blob/master/src/System.Linq/src/System/Linq/AnyAll.cs).
It irks me to have to write if( myCollection != null && myCollection.Any() )
Am I wrong, as a client of this code, to expect that e.g. ((int)null).Any() should return false?
c# .net linq extension-method
asked 2 hours ago
thisextendsthat
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up vote
2
down vote
favorite
When you create an extension method you can, of course, call it on null.But, unlike an instance method call, calling it on null doesn't have to throw a NullReferenceException -> you have to check and throw it manually.
For the implementation of the Linq extension method Any() Microsoft decided that they should throw a NullReferenceException (https://github.com/dotnet/corefx/blob/master/src/System.Linq/src/System/Linq/AnyAll.cs).
It irks me to have to write if( myCollection != null && myCollection.Any() )
Am I wrong, as a client of this code, to expect that e.g. ((int)null).Any() should return false?
c# .net linq extension-method
asked 2 hours ago
thisextendsthat
1172
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thisextendsthat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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This is too opinionated for this site, however I too am constantly annoyed about checking for null when I treat a null collection and empty collection exactly the same: Don't do anything with it. However, this breaks down when a null pointer is meaningful versus an empty collection (hide search results if null versus "Your search returned no results").
– Greg Burghardt
8 mins ago
add a comment |Â
up vote
2
down vote
favorite
up vote
2
down vote
favorite
When you create an extension method you can, of course, call it on null.But, unlike an instance method call, calling it on null doesn't have to throw a NullReferenceException -> you have to check and throw it manually.
For the implementation of the Linq extension method Any() Microsoft decided that they should throw a NullReferenceException (https://github.com/dotnet/corefx/blob/master/src/System.Linq/src/System/Linq/AnyAll.cs).
It irks me to have to write if( myCollection != null && myCollection.Any() )
Am I wrong, as a client of this code, to expect that e.g. ((int)null).Any() should return false?
c# .net linq extension-method
asked 2 hours ago
thisextendsthat
1172
New contributor
thisextendsthat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
When you create an extension method you can, of course, call it on null.But, unlike an instance method call, calling it on null doesn't have to throw a NullReferenceException -> you have to check and throw it manually.
For the implementation of the Linq extension method Any() Microsoft decided that they should throw a NullReferenceException (https://github.com/dotnet/corefx/blob/master/src/System.Linq/src/System/Linq/AnyAll.cs).
It irks me to have to write if( myCollection != null && myCollection.Any() )
Am I wrong, as a client of this code, to expect that e.g. ((int)null).Any() should return false?
c# .net linq extension-method
c# .net linq extension-method
asked 2 hours ago
thisextendsthat
1172
New contributor
thisextendsthat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
thisextendsthat
1172
New contributor
thisextendsthat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
thisextendsthat
1172
New contributor
thisextendsthat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
thisextendsthat
1172
asked 2 hours ago
thisextendsthat
1172
1172
New contributor
thisextendsthat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
thisextendsthat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
thisextendsthat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
This is too opinionated for this site, however I too am constantly annoyed about checking for null when I treat a null collection and empty collection exactly the same: Don't do anything with it. However, this breaks down when a null pointer is meaningful versus an empty collection (hide search results if null versus "Your search returned no results").
– Greg Burghardt
8 mins ago
add a comment |Â
This is too opinionated for this site, however I too am constantly annoyed about checking for null when I treat a null collection and empty collection exactly the same: Don't do anything with it. However, this breaks down when a null pointer is meaningful versus an empty collection (hide search results if null versus "Your search returned no results").
– Greg Burghardt
8 mins ago
This is too opinionated for this site, however I too am constantly annoyed about checking for null when I treat a null collection and empty collection exactly the same: Don't do anything with it. However, this breaks down when a null pointer is meaningful versus an empty collection (hide search results if null versus "Your search returned no results").
– Greg Burghardt
8 mins ago
This is too opinionated for this site, however I too am constantly annoyed about checking for null when I treat a null collection and empty collection exactly the same: Don't do anything with it. However, this breaks down when a null pointer is meaningful versus an empty collection (hide search results if null versus "Your search returned no results").
– Greg Burghardt
8 mins ago
add a comment |Â
4 Answers
4
active
oldest
votes
up vote
5
down vote
First off, it appears that that source code will throw ArgumentNullException, not NullReferenceException.
Having said that, in many cases you already know that your collection is not null, because this code is only called from code that knows that the collection already exists, so you won't have to put the null check in there very often. But if you don't know that it exists, then it does make sense to check before calling Any() on it.
Am I wrong, as a client of this code, to expect that e.g.
((int)null).Any()should returnfalse?
Yes. The question that Any() answers is "does this collection contain any elements?" If this collection does not exist, then the question itself is nonsensical; it can neither contain nor not-contain anything, because it doesn't exist.
answered 1 hour ago
Mason Wheeler
72.9k18206294
add a comment |Â
up vote
3
down vote
I have a bag with five potatoes in it. Are there .Any() potatoes in the bag?
"Yes," you say. <= true
I take all of the potatoes out and eat them. Are there .Any() potatoes in the bag?
"No," you say. <= false
I completely incinerate the bag in a fire. Are there .Any() potatoes in the bag now?
"There is no bag." <= ArgumentNullException
answered 40 mins ago
Dan Wilson
5208
1
Love the illustration! +1 Still annoys me to do a null check when I don't care if the bag was incinerated though. I'm totally including this extension method in all future projects:IEnumerable<T>.IsIncineratedOrEmpty()
– Greg Burghardt
12 mins ago
add a comment |Â
up vote
0
down vote
Null means missing information, not no elements.
You might consider more broadly avoiding null -- for example, use one of the built-in empty enumerables to represent a collection with no elements instead of null.
If you are returning null in some circumstances, you might change that to return the empty collection. (Otherwise, if you're finding null's returned by library methods (not yours), that's unfortunate, and I would wrap them to normalize.) See also
https://stackoverflow.com/questions/1191919/what-does-linq-return-when-the-results-are-empty
answered 1 hour ago
Erik Eidt
20.4k33051
Thatnulldoesn't mean no elements is a matter of using a sensible convention. Just think about native OLESTRINGS, where it actually does mean that.
– Deduplicator
1 hour ago
@Deduplicator, are you talking about Microsoft's Object Linking and Embedding perchance? If you are let's recall that OLE is from the '90s! Looking more currently, many modern languages (C#,Java,Swift) are providing facilities to eliminate/eradicate uses of null.
– Erik Eidt
54 mins ago
add a comment |Â
up vote
0
down vote
Am I wrong, as a client of this code, to expect that e.g. ((int)null).Any() should return false?
Yes, simply because you're in C# and that behavior is well defined and documented.
If you were making your own library, or if you were using a different language with different exception culture then it would be more reasonable to expect false.
Personally I feel as though that is a safer approach that makes your program more robust, but it's debatable at least.
answered 27 mins ago
Telastyn
90.1k24203310
add a comment |Â
4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
5
down vote
First off, it appears that that source code will throw ArgumentNullException, not NullReferenceException.
Having said that, in many cases you already know that your collection is not null, because this code is only called from code that knows that the collection already exists, so you won't have to put the null check in there very often. But if you don't know that it exists, then it does make sense to check before calling Any() on it.
Am I wrong, as a client of this code, to expect that e.g.
((int)null).Any()should returnfalse?
Yes. The question that Any() answers is "does this collection contain any elements?" If this collection does not exist, then the question itself is nonsensical; it can neither contain nor not-contain anything, because it doesn't exist.
answered 1 hour ago
Mason Wheeler
72.9k18206294
add a comment |Â
up vote
5
down vote
First off, it appears that that source code will throw ArgumentNullException, not NullReferenceException.
Having said that, in many cases you already know that your collection is not null, because this code is only called from code that knows that the collection already exists, so you won't have to put the null check in there very often. But if you don't know that it exists, then it does make sense to check before calling Any() on it.
Am I wrong, as a client of this code, to expect that e.g.
((int)null).Any()should returnfalse?
Yes. The question that Any() answers is "does this collection contain any elements?" If this collection does not exist, then the question itself is nonsensical; it can neither contain nor not-contain anything, because it doesn't exist.
answered 1 hour ago
Mason Wheeler
72.9k18206294
add a comment |Â
up vote
5
down vote
up vote
5
down vote
First off, it appears that that source code will throw ArgumentNullException, not NullReferenceException.
Having said that, in many cases you already know that your collection is not null, because this code is only called from code that knows that the collection already exists, so you won't have to put the null check in there very often. But if you don't know that it exists, then it does make sense to check before calling Any() on it.
Am I wrong, as a client of this code, to expect that e.g.
((int)null).Any()should returnfalse?
Yes. The question that Any() answers is "does this collection contain any elements?" If this collection does not exist, then the question itself is nonsensical; it can neither contain nor not-contain anything, because it doesn't exist.
answered 1 hour ago
Mason Wheeler
72.9k18206294
First off, it appears that that source code will throw ArgumentNullException, not NullReferenceException.
Having said that, in many cases you already know that your collection is not null, because this code is only called from code that knows that the collection already exists, so you won't have to put the null check in there very often. But if you don't know that it exists, then it does make sense to check before calling Any() on it.
Am I wrong, as a client of this code, to expect that e.g.
((int)null).Any()should returnfalse?
Yes. The question that Any() answers is "does this collection contain any elements?" If this collection does not exist, then the question itself is nonsensical; it can neither contain nor not-contain anything, because it doesn't exist.
answered 1 hour ago
Mason Wheeler
72.9k18206294
answered 1 hour ago
Mason Wheeler
72.9k18206294
answered 1 hour ago
Mason Wheeler
72.9k18206294
answered 1 hour ago
Mason Wheeler
72.9k18206294
72.9k18206294
add a comment |Â
add a comment |Â
up vote
3
down vote
I have a bag with five potatoes in it. Are there .Any() potatoes in the bag?
"Yes," you say. <= true
I take all of the potatoes out and eat them. Are there .Any() potatoes in the bag?
"No," you say. <= false
I completely incinerate the bag in a fire. Are there .Any() potatoes in the bag now?
"There is no bag." <= ArgumentNullException
answered 40 mins ago
Dan Wilson
5208
1
Love the illustration! +1 Still annoys me to do a null check when I don't care if the bag was incinerated though. I'm totally including this extension method in all future projects:IEnumerable<T>.IsIncineratedOrEmpty()
– Greg Burghardt
12 mins ago
add a comment |Â
up vote
3
down vote
I have a bag with five potatoes in it. Are there .Any() potatoes in the bag?
"Yes," you say. <= true
I take all of the potatoes out and eat them. Are there .Any() potatoes in the bag?
"No," you say. <= false
I completely incinerate the bag in a fire. Are there .Any() potatoes in the bag now?
"There is no bag." <= ArgumentNullException
answered 40 mins ago
Dan Wilson
5208
1
Love the illustration! +1 Still annoys me to do a null check when I don't care if the bag was incinerated though. I'm totally including this extension method in all future projects:IEnumerable<T>.IsIncineratedOrEmpty()
– Greg Burghardt
12 mins ago
add a comment |Â
up vote
3
down vote
up vote
3
down vote
I have a bag with five potatoes in it. Are there .Any() potatoes in the bag?
"Yes," you say. <= true
I take all of the potatoes out and eat them. Are there .Any() potatoes in the bag?
"No," you say. <= false
I completely incinerate the bag in a fire. Are there .Any() potatoes in the bag now?
"There is no bag." <= ArgumentNullException
answered 40 mins ago
Dan Wilson
5208
I have a bag with five potatoes in it. Are there .Any() potatoes in the bag?
"Yes," you say. <= true
I take all of the potatoes out and eat them. Are there .Any() potatoes in the bag?
"No," you say. <= false
I completely incinerate the bag in a fire. Are there .Any() potatoes in the bag now?
"There is no bag." <= ArgumentNullException
answered 40 mins ago
Dan Wilson
5208
answered 40 mins ago
Dan Wilson
5208
answered 40 mins ago
Dan Wilson
5208
answered 40 mins ago
Dan Wilson
5208
5208
1
Love the illustration! +1 Still annoys me to do a null check when I don't care if the bag was incinerated though. I'm totally including this extension method in all future projects:IEnumerable<T>.IsIncineratedOrEmpty()
– Greg Burghardt
12 mins ago
add a comment |Â
1
Love the illustration! +1 Still annoys me to do a null check when I don't care if the bag was incinerated though. I'm totally including this extension method in all future projects:IEnumerable<T>.IsIncineratedOrEmpty()
– Greg Burghardt
12 mins ago
1
1
Love the illustration! +1 Still annoys me to do a null check when I don't care if the bag was incinerated though. I'm totally including this extension method in all future projects:
IEnumerable<T>.IsIncineratedOrEmpty()– Greg Burghardt
12 mins ago
Love the illustration! +1 Still annoys me to do a null check when I don't care if the bag was incinerated though. I'm totally including this extension method in all future projects:
IEnumerable<T>.IsIncineratedOrEmpty()– Greg Burghardt
12 mins ago
add a comment |Â
up vote
0
down vote
Null means missing information, not no elements.
You might consider more broadly avoiding null -- for example, use one of the built-in empty enumerables to represent a collection with no elements instead of null.
If you are returning null in some circumstances, you might change that to return the empty collection. (Otherwise, if you're finding null's returned by library methods (not yours), that's unfortunate, and I would wrap them to normalize.) See also
https://stackoverflow.com/questions/1191919/what-does-linq-return-when-the-results-are-empty
answered 1 hour ago
Erik Eidt
20.4k33051
Thatnulldoesn't mean no elements is a matter of using a sensible convention. Just think about native OLESTRINGS, where it actually does mean that.
– Deduplicator
1 hour ago
@Deduplicator, are you talking about Microsoft's Object Linking and Embedding perchance? If you are let's recall that OLE is from the '90s! Looking more currently, many modern languages (C#,Java,Swift) are providing facilities to eliminate/eradicate uses of null.
– Erik Eidt
54 mins ago
add a comment |Â
up vote
0
down vote
Null means missing information, not no elements.
You might consider more broadly avoiding null -- for example, use one of the built-in empty enumerables to represent a collection with no elements instead of null.
If you are returning null in some circumstances, you might change that to return the empty collection. (Otherwise, if you're finding null's returned by library methods (not yours), that's unfortunate, and I would wrap them to normalize.) See also
https://stackoverflow.com/questions/1191919/what-does-linq-return-when-the-results-are-empty
answered 1 hour ago
Erik Eidt
20.4k33051
Thatnulldoesn't mean no elements is a matter of using a sensible convention. Just think about native OLESTRINGS, where it actually does mean that.
– Deduplicator
1 hour ago
@Deduplicator, are you talking about Microsoft's Object Linking and Embedding perchance? If you are let's recall that OLE is from the '90s! Looking more currently, many modern languages (C#,Java,Swift) are providing facilities to eliminate/eradicate uses of null.
– Erik Eidt
54 mins ago
add a comment |Â
up vote
0
down vote
up vote
0
down vote
Null means missing information, not no elements.
You might consider more broadly avoiding null -- for example, use one of the built-in empty enumerables to represent a collection with no elements instead of null.
If you are returning null in some circumstances, you might change that to return the empty collection. (Otherwise, if you're finding null's returned by library methods (not yours), that's unfortunate, and I would wrap them to normalize.) See also
https://stackoverflow.com/questions/1191919/what-does-linq-return-when-the-results-are-empty
answered 1 hour ago
Erik Eidt
20.4k33051
Null means missing information, not no elements.
You might consider more broadly avoiding null -- for example, use one of the built-in empty enumerables to represent a collection with no elements instead of null.
If you are returning null in some circumstances, you might change that to return the empty collection. (Otherwise, if you're finding null's returned by library methods (not yours), that's unfortunate, and I would wrap them to normalize.) See also
https://stackoverflow.com/questions/1191919/what-does-linq-return-when-the-results-are-empty
answered 1 hour ago
Erik Eidt
20.4k33051
answered 1 hour ago
Erik Eidt
20.4k33051
answered 1 hour ago
Erik Eidt
20.4k33051
answered 1 hour ago
Erik Eidt
20.4k33051
20.4k33051
Thatnulldoesn't mean no elements is a matter of using a sensible convention. Just think about native OLESTRINGS, where it actually does mean that.
– Deduplicator
1 hour ago
@Deduplicator, are you talking about Microsoft's Object Linking and Embedding perchance? If you are let's recall that OLE is from the '90s! Looking more currently, many modern languages (C#,Java,Swift) are providing facilities to eliminate/eradicate uses of null.
– Erik Eidt
54 mins ago
add a comment |Â
Thatnulldoesn't mean no elements is a matter of using a sensible convention. Just think about native OLESTRINGS, where it actually does mean that.
– Deduplicator
1 hour ago
@Deduplicator, are you talking about Microsoft's Object Linking and Embedding perchance? If you are let's recall that OLE is from the '90s! Looking more currently, many modern languages (C#,Java,Swift) are providing facilities to eliminate/eradicate uses of null.
– Erik Eidt
54 mins ago
That
null doesn't mean no elements is a matter of using a sensible convention. Just think about native OLESTRINGS, where it actually does mean that.– Deduplicator
1 hour ago
That
null doesn't mean no elements is a matter of using a sensible convention. Just think about native OLESTRINGS, where it actually does mean that.– Deduplicator
1 hour ago
@Deduplicator, are you talking about Microsoft's Object Linking and Embedding perchance? If you are let's recall that OLE is from the '90s! Looking more currently, many modern languages (C#,Java,Swift) are providing facilities to eliminate/eradicate uses of null.
– Erik Eidt
54 mins ago
@Deduplicator, are you talking about Microsoft's Object Linking and Embedding perchance? If you are let's recall that OLE is from the '90s! Looking more currently, many modern languages (C#,Java,Swift) are providing facilities to eliminate/eradicate uses of null.
– Erik Eidt
54 mins ago
add a comment |Â
up vote
0
down vote
Am I wrong, as a client of this code, to expect that e.g. ((int)null).Any() should return false?
Yes, simply because you're in C# and that behavior is well defined and documented.
If you were making your own library, or if you were using a different language with different exception culture then it would be more reasonable to expect false.
Personally I feel as though that is a safer approach that makes your program more robust, but it's debatable at least.
answered 27 mins ago
Telastyn
90.1k24203310
add a comment |Â
up vote
0
down vote
Am I wrong, as a client of this code, to expect that e.g. ((int)null).Any() should return false?
Yes, simply because you're in C# and that behavior is well defined and documented.
If you were making your own library, or if you were using a different language with different exception culture then it would be more reasonable to expect false.
Personally I feel as though that is a safer approach that makes your program more robust, but it's debatable at least.
answered 27 mins ago
Telastyn
90.1k24203310
add a comment |Â
up vote
0
down vote
up vote
0
down vote
Am I wrong, as a client of this code, to expect that e.g. ((int)null).Any() should return false?
Yes, simply because you're in C# and that behavior is well defined and documented.
If you were making your own library, or if you were using a different language with different exception culture then it would be more reasonable to expect false.
Personally I feel as though that is a safer approach that makes your program more robust, but it's debatable at least.
answered 27 mins ago
Telastyn
90.1k24203310
Am I wrong, as a client of this code, to expect that e.g. ((int)null).Any() should return false?
Yes, simply because you're in C# and that behavior is well defined and documented.
If you were making your own library, or if you were using a different language with different exception culture then it would be more reasonable to expect false.
Personally I feel as though that is a safer approach that makes your program more robust, but it's debatable at least.
answered 27 mins ago
Telastyn
90.1k24203310
answered 27 mins ago
Telastyn
90.1k24203310
answered 27 mins ago
Telastyn
90.1k24203310
answered 27 mins ago
Telastyn
90.1k24203310
90.1k24203310
add a comment |Â
add a comment |Â
thisextendsthat is a new contributor. Be nice, and check out our Code of Conduct.
thisextendsthat is a new contributor. Be nice, and check out our Code of Conduct.
thisextendsthat is a new contributor. Be nice, and check out our Code of Conduct.
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This is too opinionated for this site, however I too am constantly annoyed about checking for null when I treat a null collection and empty collection exactly the same: Don't do anything with it. However, this breaks down when a null pointer is meaningful versus an empty collection (hide search results if null versus "Your search returned no results").
– Greg Burghardt
8 mins ago