Assign By Reference
-
Is there any way to assign an object by address in C#? (I want to use the word reference but it complicates the question). It's like you can have reference behaviour through functions that you cannot have WITHIN the function. Example: private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { objIn = new MyClass() //Creates a new object in the function that called this procedure } But if did private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { m_MyClass = objIn; } public void SomeOtherFunction() { m_MyClass = new MyClass() //Now the calling function's object is forever unlinked } My question is: //Is there some way to do something more like m_Myclass = ref objIn; //???? I thank everyone who wants to be helpful but I am not looking for a workaround, I am trying to advance my understanding of .NET. Thanks again, All.
-
Is there any way to assign an object by address in C#? (I want to use the word reference but it complicates the question). It's like you can have reference behaviour through functions that you cannot have WITHIN the function. Example: private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { objIn = new MyClass() //Creates a new object in the function that called this procedure } But if did private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { m_MyClass = objIn; } public void SomeOtherFunction() { m_MyClass = new MyClass() //Now the calling function's object is forever unlinked } My question is: //Is there some way to do something more like m_Myclass = ref objIn; //???? I thank everyone who wants to be helpful but I am not looking for a workaround, I am trying to advance my understanding of .NET. Thanks again, All.
Ummm... what? It's hard to read that code; put it in pre tags (select it and click
code block).thenutz72 wrote:
It's like you can have reference behaviour through functions that you cannot have WITHIN the function.
C# (.net) is all about references.
thenutz72 wrote:
is forever unlinked
I don't know what that's supposed to mean.
thenutz72 wrote:
way to do something more like
No, that's silly.
-
Is there any way to assign an object by address in C#? (I want to use the word reference but it complicates the question). It's like you can have reference behaviour through functions that you cannot have WITHIN the function. Example: private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { objIn = new MyClass() //Creates a new object in the function that called this procedure } But if did private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { m_MyClass = objIn; } public void SomeOtherFunction() { m_MyClass = new MyClass() //Now the calling function's object is forever unlinked } My question is: //Is there some way to do something more like m_Myclass = ref objIn; //???? I thank everyone who wants to be helpful but I am not looking for a workaround, I am trying to advance my understanding of .NET. Thanks again, All.
-
Is there any way to assign an object by address in C#? (I want to use the word reference but it complicates the question). It's like you can have reference behaviour through functions that you cannot have WITHIN the function. Example: private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { objIn = new MyClass() //Creates a new object in the function that called this procedure } But if did private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { m_MyClass = objIn; } public void SomeOtherFunction() { m_MyClass = new MyClass() //Now the calling function's object is forever unlinked } My question is: //Is there some way to do something more like m_Myclass = ref objIn; //???? I thank everyone who wants to be helpful but I am not looking for a workaround, I am trying to advance my understanding of .NET. Thanks again, All.
thenutz72 wrote:
It's like you can have reference behaviour through functions that you cannot have WITHIN the function.
Pretty much everything is done by reference:
MyObject foo = new MyObject();
foo is a reference to the object created by the constructor. When it gets used it is automatically de-referenced, see this[^] for the c# boxing and unboxing model. When you pass an object to a method it is passed as a reference by default, you have to tell the method if you want it passed by value. If you need pointers you have to use unmanagedunsafe code, where pointers are available, but in C# you rarely need it. I've being doing this for 10 years, and the only time I had to use pointers was during some interop work I was doing. Oh and a another time after I'd just graduated using c++ and didn't know how C# really worked, which was a bit embarrasing :-) Finally, please tag up your code with <pre> , it makes it easier to read. Otherwise you'll get responses of varying degrees of snottiness. [edit]: When I said unmanaged code, I of course meant unsafe code. Better have a nice nap and a cup of tea, I'm getting old!
Sort of a cross between Lawrence of Arabia and Dilbert.[^]
modified on Saturday, October 9, 2010 1:03 PM
-
Is there any way to assign an object by address in C#? (I want to use the word reference but it complicates the question). It's like you can have reference behaviour through functions that you cannot have WITHIN the function. Example: private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { objIn = new MyClass() //Creates a new object in the function that called this procedure } But if did private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { m_MyClass = objIn; } public void SomeOtherFunction() { m_MyClass = new MyClass() //Now the calling function's object is forever unlinked } My question is: //Is there some way to do something more like m_Myclass = ref objIn; //???? I thank everyone who wants to be helpful but I am not looking for a workaround, I am trying to advance my understanding of .NET. Thanks again, All.
-
thenutz72 wrote:
It's like you can have reference behaviour through functions that you cannot have WITHIN the function.
Pretty much everything is done by reference:
MyObject foo = new MyObject();
foo is a reference to the object created by the constructor. When it gets used it is automatically de-referenced, see this[^] for the c# boxing and unboxing model. When you pass an object to a method it is passed as a reference by default, you have to tell the method if you want it passed by value. If you need pointers you have to use unmanagedunsafe code, where pointers are available, but in C# you rarely need it. I've being doing this for 10 years, and the only time I had to use pointers was during some interop work I was doing. Oh and a another time after I'd just graduated using c++ and didn't know how C# really worked, which was a bit embarrasing :-) Finally, please tag up your code with <pre> , it makes it easier to read. Otherwise you'll get responses of varying degrees of snottiness. [edit]: When I said unmanaged code, I of course meant unsafe code. Better have a nice nap and a cup of tea, I'm getting old!
Sort of a cross between Lawrence of Arabia and Dilbert.[^]
modified on Saturday, October 9, 2010 1:03 PM
Thanks Kieth, But in my code examples you'll see the ref keyword does act like a pointer to an object. Where as the assignment operator just assigns a reference. In the former, there are two variables with the same address. The latter, two variables that only point to the same reference. Use of the new keyword in each scenario will confirm the difference. I just find it odd that a function parameter can make use of pointers to objects but there's no way to duplicate that behaviour inside of a function. I was able to use unsafe code and pointers to primitive types to share addresses across multple variables. But was unable to do the same with a class/object instance.
-
Thanks Kieth, But in my code examples you'll see the ref keyword does act like a pointer to an object. Where as the assignment operator just assigns a reference. In the former, there are two variables with the same address. The latter, two variables that only point to the same reference. Use of the new keyword in each scenario will confirm the difference. I just find it odd that a function parameter can make use of pointers to objects but there's no way to duplicate that behaviour inside of a function. I was able to use unsafe code and pointers to primitive types to share addresses across multple variables. But was unable to do the same with a class/object instance.
You still haven't explained your question clearly.
-
Thanks Kieth, But in my code examples you'll see the ref keyword does act like a pointer to an object. Where as the assignment operator just assigns a reference. In the former, there are two variables with the same address. The latter, two variables that only point to the same reference. Use of the new keyword in each scenario will confirm the difference. I just find it odd that a function parameter can make use of pointers to objects but there's no way to duplicate that behaviour inside of a function. I was able to use unsafe code and pointers to primitive types to share addresses across multple variables. But was unable to do the same with a class/object instance.
First, in your code, the
refkeyword is redundant, the reference pointer is passed round on objects by default, not the value itself. Second, I'm still really not clear on your question.private MyClass
public void MyFunction(MyClass objIn)
{
m_MyClass = objIn;
}public void SomeOtherFunction()
{
m_MyClass = new MyClass() //*Now the calling function's object is forever unlinked*
// Actually, it isn't just unlinked, the m_MyClass reference is replaced with the one
// you have just instantiated, The original object is orphaned and ready up for Garbage
// collection as no reference to it exists any more.
}public void Main()
{
MyFunction(new MyClass());
SomeOtherFunction();
}Which language are you used to using and what exactly are you trying to achieve? If you need pointers you are probably going about things the wrong way in C#.
-
Is there any way to assign an object by address in C#? (I want to use the word reference but it complicates the question). It's like you can have reference behaviour through functions that you cannot have WITHIN the function. Example: private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { objIn = new MyClass() //Creates a new object in the function that called this procedure } But if did private MyClass m_MyClass; public void MyFunction(ref MyClass objIn) { m_MyClass = objIn; } public void SomeOtherFunction() { m_MyClass = new MyClass() //Now the calling function's object is forever unlinked } My question is: //Is there some way to do something more like m_Myclass = ref objIn; //???? I thank everyone who wants to be helpful but I am not looking for a workaround, I am trying to advance my understanding of .NET. Thanks again, All.
I am not sure if I understand what you want to accomplish. I guess you could try the
outkeyword instead of therefkeyword.