question on namespaces


A

Aniket Sule

Hi,
I am trying to use a class from one namespace in another via the using
directive. The 2 namespaces have some part of the name in common (A.B.x,
A.B.y). However in the second namespace, I am unable to access the class
from the first without qualifying it, which is what i want to avoid. Any
ideas what I am doing wrong?

I am attaching the code and compiler error below to show exactly what I am
trying to do,

Any help is greatly appreciated,
Thanks
Aniket

file1.cs -
using System;
namespace apstry.A.apstry1
{
public class apstry1
{
public apstry1()
{
}
public static void Dummy()
{
System.Windows.Forms.MessageBox.Show("dummy call");
}
}
public class noName
{
public noName()
{
}
}
}

file2.cs -
using System;
using apstry.A.apstry1;
namespace apstry.A.apstry2
{
public class Class11
{
public Class11()
{
System.Windows.Forms.MessageBox.Show("duh");
apstry1.apstry1.Dummy(); // -- this works
apstry1.Dummy();

/*--gives the error C:\temp\apstry2\apstry2\Class1.cs(22): The type or
namespace name 'Dummy' does not exist in the class or namespace
'apstry.A.apstry1' (are you missing an assembly reference?)*/

noName y;
noName z;

}
public void duh()
{
}
}
}
 
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G

Goran Genter

I think that the problem is in :

namespace apstry.A.apstry1
{
public class apstry1
{
..
..
..

You have a namespace and class with same name : apstry1.
 
M

Mark Johnson

The name of the class and the end of the namespace are the same so the
compiler doesn't know which one you want without prefixing the name of the
class with the last part of the namespace.
 
A

Aniket Sule

Thanks a lot, that explains it. I dont have control over the class naming
right now, so looks like I will have to go with the qualified name
 
T

Tyler Dixon

It's because your first class has the same name as the enclosing namespace.
The compiler thinks you are trying to call

apstry.A.apstry1.Dummy()

which of course doesn't work because namespaces cannot contain methods
directly. Just change the name of the first class to something else, and
the compiler won't get confused.
 
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1

100

Hi Aniket,
If you don't have control over the name of the class. You might be able to
change the name you are using only in file2. You can do that using aliases

file2:

using System;
using apstry.A.apstry1;
using NewName = apstry.A.apstry1.apstry1; //a new name for the class apstry1

and then call Dummy like:
NewName.Dummy();

HTH
B\rgds
100
 
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V

Val Savvateev

I'll agree with Joe that this the problem occurs because of the way name
resolutions is done in C#. However it's not that simple - for instance try
to move [using apstry.A.apstry1;] directive _inside_ apstry2 namespace and
see what happens.
If you find it entertaining you could go through sections 3.7, 3.8 and 9 of
the language cpecs, but I'd suggest not to bother and just avoid name
collisions.

Regards,
Val.
 

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