Programming .NET Components
by Juval Lowy

The unconfirmed error reports are from readers.  They have not yet been 
approved or disproved by the author or editor and represent solely the
opinion of the reader.

Here's a key to the markup:
        [page-number]: serious technical mistake
        {page-number}: minor technical mistake
        <page-number>: important language/formatting problem
        (page-number): language change or minor formatting problem
        ?page-number?: reader question or request for clarification

This page was updated September 29, 2004.


UNCONFIRMED  errors and comments from readers: 


{18}  1st paragraph, first line.;
"When the compiler generates an EXE file. its entry point is the WinMain() method."

I've search Google, all said the entry point is CorExeMain.
I also dump the PE information of a .exe file, there's no
WinMain() but only a _CoreExeMain imported from MSCorEE.dll.


{29}  3rd paragraph;
The book incorrectly describes how "protected internal" works.  It says "To
subclasses outside the assembly, the DoWork() method appears as an inaccessible
private method...".

This is not true.  The method shows up as protected and is accessible from subclasses
outside the assembly.


{210}  last code sample on page;
I believe this line:
currentThread.ApartmentState = ApartmentState.STA;

should use the workerThread object, rather than the currentThread object:
workerThread.ApartmentState = ApartmentState.STA;


[239]  The note;
Note: I have not finished reading the entire book yet, but I must say, this is one of
the best, if not The Best, books that I've read on the subject.

The note states: ".., the calling assembly must reference the assembly being
specified"

I believe this is not absolutely true if interfaces are used.

Here is an example (which I wrote some time ago to prove some other point) that
involves 4 assemblies:
1) "Interfaces" assembly declares Interface1 and interface2
2) "ClassLibrary1" assembly contains TestClass1 that implements Interface1
3) "ClassLibrary2" assembly contains TestClass2 and TestClass3, both implement
Interface2
4) "DomainTest" contains a Form which loads ClassLibrary1 in one domain, and
ClassLibrary2 in another domain, but it only references the Interfaces assembly.
Following are excerpts from the Interfaces and DomainTest assemblies:

"Interfaces" contains the following
public interface Interface1
{
	void Test();
}
public interface Interface2:Interface1
{
	void OtherClasses(Interface1 cls2, Interface1 cls3);
}

DomainTest contains the following code:

AppDomain appDomain1  = null;
AppDomain appDomain2  = null;
Interface1 testClass1 = null;
Interface2 testClass2 = null;
Interface2 testClass3 = null;

private void LoadDomain2()
{
	try
	{
		AppDomainSetup setup2 = new AppDomainSetup();
		setup2.ApplicationName = "TestClass2";

		appDomain2 = AppDomain.CreateDomain("Domain2", null, setup2);

		testClass2 = (Interface2)
appDomain2.CreateInstanceFromAndUnwrap("ClassLibrary2.dll",
"ClassLibrary2.TestClass2");
		testClass3 = (Interface2)
appDomain2.CreateInstanceFromAndUnwrap("ClassLibrary2.dll",
"ClassLibrary2.TestClass3");
		if(testClass1 != null)
		{
			testClass1.OtherClasses(testClass2,testClass3);
		}
	}
	catch(Exception ex1)
	{
		MessageBox.Show("LoadDomain2: " + ex1.ToString());
	}
}


private void LoadDomain1()
{
	try
	{
		AppDomainSetup setup1 = new AppDomainSetup();
		setup1.ApplicationName = "TestClass1";

		appDomain1 = AppDomain.CreateDomain("Domain1", null, setup1);

		testClass1 = (Interface1)
appDomain1.CreateInstanceFromAndUnwrap("ClassLibrary1.dll",
"ClassLibrary1.TestClass1");
		testClass1.OtherClasses(testClass2,testClass3);
	}
	catch(Exception ex1)
	{
		MessageBox.Show("LoadDomain1: " + ex1.ToString());
	}
}

private void btnTest_Click(object sender, System.EventArgs e)
{
	if (testClass1 != null)
	{
		testClass1.Test(); //verifies that class1 has access to both class2 and class3
	}
}


{285}  First code sample;
I believe this code:
IChannel channel = new TcpChannel();
should pass port 0 into the TcpChannel constructor:
IChannel channel = new TcpChannel(0);

The MSDN documentation states that if the default constructor is used, "the channel
functions only as a client channel, and does not listen on any ports", so it seems
that Remote Callbacks would not work.