'Item': member names cannot be the same as their enclosing type
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My schoolmate told me about a situation he faced while coding using C#. if we have the following code snippet :
public class Item
{
public int this[int y]
{
get
{
return 0;
}
}
}While compiling an error will appear saying: 'Item': member names cannot be the same as their enclosing type :wtf: First I got confused, since I knew that I was defining indexer property for the class 'Item'. After I referred to MSDN I read this : Compiler Error CS0542 If your class is named 'Item' and has an indexer declared as this, you may get this error. A default indexer is given the name 'Item' in the emitted code, creating the conflict. At the end I think that this MSIL specification mustn't be exist at all.:cool:
Best wishes, Redwan Al-Bougha
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Ok, it's time for a little nitpicking then :-) (or, as we say in French, cutting hairs in four). Beware, I've 44 years of experience at that game :-) It means that everything I say here has absolutely no importance at all, and is by no way an attack on anyone. It's just saying something for the pleasure of saying something. The ".ctor" is not a C# name, it is a CLR/MSIL/whatever name. When I write a constructor for my C# class, I dont type ".ctor", I type the name of my class as the name of the method. Now, whether the compiler has an urgent need to create MSIL code named ".ctor" or "Groborozgruduruk" is totally irrelevant. When I program in C#, and also when I read C# code written by anyone else, I know that if a method is declared that has the same name as the class, it is a constructor. In Delphi, type casts use the same syntax as a function call, so having a function and a type with the same name is not a good idea there neither. Other languages may still have other good reasons to abhor that. This is a good reason why I agree with the compiler when it insists that I don't call my method the same name as the class. This brings the second question: as the compiler internally creates a method named "Item" as the implementation of the default indexer, does it really impose an unbearable burden on the creativity of programmers? Of course, it means that you cannot have a class named "Item" that has an indexer. But wait! Do you really think a good design would involve a class named very generically "Item" that has a default indexer (and so is itself composed of a collection of something else.) What are these called then? "SubItem" maybe? What if SubItem has itself an indexer? "SubSubItem"? "YetAnoterSubItem"? If you don't give meaningful names to your classes and methods, you are of course welcome to do so, but please don't say the compiler is restricting your creativity :-) On the other hand, now we know where the coding horror is :-)
-- Quidquid latine dictum sit, altum sonatur. http://streambolics.flimbase.com S. L.
WilliamSauron wrote:
This brings the second question: as the compiler internally creates a method named "Item" as the implementation of the default indexer, does it really impose an unbearable burden on the creativity of programmers?
No, they provide an easy way around it. See
IndexerNameAttribute.xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 1 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x)) -
Ok, it's time for a little nitpicking then :-) (or, as we say in French, cutting hairs in four). Beware, I've 44 years of experience at that game :-) It means that everything I say here has absolutely no importance at all, and is by no way an attack on anyone. It's just saying something for the pleasure of saying something. The ".ctor" is not a C# name, it is a CLR/MSIL/whatever name. When I write a constructor for my C# class, I dont type ".ctor", I type the name of my class as the name of the method. Now, whether the compiler has an urgent need to create MSIL code named ".ctor" or "Groborozgruduruk" is totally irrelevant. When I program in C#, and also when I read C# code written by anyone else, I know that if a method is declared that has the same name as the class, it is a constructor. In Delphi, type casts use the same syntax as a function call, so having a function and a type with the same name is not a good idea there neither. Other languages may still have other good reasons to abhor that. This is a good reason why I agree with the compiler when it insists that I don't call my method the same name as the class. This brings the second question: as the compiler internally creates a method named "Item" as the implementation of the default indexer, does it really impose an unbearable burden on the creativity of programmers? Of course, it means that you cannot have a class named "Item" that has an indexer. But wait! Do you really think a good design would involve a class named very generically "Item" that has a default indexer (and so is itself composed of a collection of something else.) What are these called then? "SubItem" maybe? What if SubItem has itself an indexer? "SubSubItem"? "YetAnoterSubItem"? If you don't give meaningful names to your classes and methods, you are of course welcome to do so, but please don't say the compiler is restricting your creativity :-) On the other hand, now we know where the coding horror is :-)
-- Quidquid latine dictum sit, altum sonatur. http://streambolics.flimbase.com S. L.
First of all thanks for your reply it was really interesting to read it, especially:
WilliamSauron wrote:
but please don't say the compiler is restricting your creativity
WilliamSauron wrote:
On the other hand, now we know where the coding horror is
I have a lot to say, but Midterm is next week so I can't write a lot now. BYE ;)
Best wishes, Redwan Al-Bougha
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Try this:
public class Item
{
[IndexerName("IRDUM")]
public int this[int y]
{
get
{
return 0;
}
}
}xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 1 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))Thanks leppie, Rob Graham already told me about
IndexerNameAttribute. But thanks for your interest :cool:Best wishes, Redwan Al-Bougha
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WilliamSauron wrote:
This brings the second question: as the compiler internally creates a method named "Item" as the implementation of the default indexer, does it really impose an unbearable burden on the creativity of programmers?
No, they provide an easy way around it. See
IndexerNameAttribute.xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 1 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))There is no need to have a way around it through an attribute. If a class has an indexer, then it is a collection of some other things; "Item" is therefore not a good name for that class. It is a Coding Horror. Give the class an appropriate name, and you don't need the attribute...
-- Quidquid latine dictum sit, altum sonatur. http://streambolics.flimbase.com S. L.
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There is no need to have a way around it through an attribute. If a class has an indexer, then it is a collection of some other things; "Item" is therefore not a good name for that class. It is a Coding Horror. Give the class an appropriate name, and you don't need the attribute...
-- Quidquid latine dictum sit, altum sonatur. http://streambolics.flimbase.com S. L.
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WilliamSauron wrote:
"Item" is therefore not a good name for that class.
No, it's simply your opinion. :)
xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 1 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))Okay, your mission, should you choose to accept it, is to provide one single example where "Item" is an appropriate name for a collection class :-) If you get caught or killed, the moderator will disavow any knowledge of this thread (which will self destruct in five seconds anyway)
-- Quidquid latine dictum sit, altum sonatur. http://streambolics.flimbase.com S. L.
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My schoolmate told me about a situation he faced while coding using C#. if we have the following code snippet :
public class Item
{
public int this[int y]
{
get
{
return 0;
}
}
}While compiling an error will appear saying: 'Item': member names cannot be the same as their enclosing type :wtf: First I got confused, since I knew that I was defining indexer property for the class 'Item'. After I referred to MSDN I read this : Compiler Error CS0542 If your class is named 'Item' and has an indexer declared as this, you may get this error. A default indexer is given the name 'Item' in the emitted code, creating the conflict. At the end I think that this MSIL specification mustn't be exist at all.:cool:
Best wishes, Redwan Al-Bougha
That's right, imagine this:
class Dog
{
public string Dog //error: you can't do this
{
get
{
return "Fido";
}
}
}The only member names that can be the same as their enclosing type are constructors. In your case the indexer, named Item, is named like its enclosing type and is not a constructor, so, that's where your problem is coming from. To fix this, change The name of the class
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That's right, imagine this:
class Dog
{
public string Dog //error: you can't do this
{
get
{
return "Fido";
}
}
}The only member names that can be the same as their enclosing type are constructors. In your case the indexer, named Item, is named like its enclosing type and is not a constructor, so, that's where your problem is coming from. To fix this, change The name of the class
Thanks Camilo, I already know that, but I post this since it has some taste of horror. :rolleyes:
Best wishes, Redwan Al-Bougha