Friday, November 30, 2007

Problem caused by dll loading mistake

It is very common that we have two versions of dll: somedll.dll(for Release build) and somedll_d.dll(for Debug build). Because of the dll dependancy complications, if these two versions were load at the same time, it may not cause build errors. However, something wrong can happen during the run time.

For example, if there is a global variable in the source file whose output is somedll.dll/somedll_d.dll, that global variable may be initialized twice (once during the load time of somedll.dll and once during the load time of somedll_d.dll). The client code then will get confused on which of the two references to use. But the fact is, it should be only one instance of that global variable existing.

Thursday, November 29, 2007

Time-saving Tips

1. Sometimes we may have weird link errors. Some of the errors will be gone if we try to delete the debug/release folder (clean) and rebuild the project.

2. If an environment involves several executables and dlls working together, their build version should match exactly. Otherwise, some bizarre behaviors may happen.

Mixed DLL Loading Problem

When using managed code inside unmanaged dll entry point, it may cause dll loading problem. For more information, follow the link below.

Monday, November 26, 2007

Be Careful of Naming

Sometimes bad naming may cause compile errors.

I named a managed enum "Event" (__value enum Event) inside a managed class "SopExt" (__gc class SopExt). In this class, I had a private field whose type is the managed enum "Event" and a pair of getter/setter of it. Later, I found that the compiler sometimes had trouble to recognize the expression like this: "sopExt->Event". The compiler sometimes also didn't recognize the type "SopExt::Event".

Obviously, neither expression is wrong. But apperently, the name of the managed enum "Event" is not a good name. Just by changing "Event" to "StreamEvent" (without even changing the name of getter/setter), the compiler error is gone. The reason that caused the compiler error is not clear. It might be that the name "Event" is too general so it confused the compiler? Anyway, good naming is a very important element in programming.

Friday, November 16, 2007

Examine std::vector in VS watch window

vector->_Myfirst[offset] or vector->_Myfirst, count

Thursday, November 15, 2007

Why using managed extension is a pain in the ***?

1. We simply cannot include unmanaged objects in a managed class. We can only include pointers to unmanaged objects.

Tuesday, November 13, 2007

__gc Array Aggregate Initialization

__gc Array Aggregate Initialization doesn't work inside a namespace (except that the method is a member of a gc class). We have to initialize each element one by one.

namespace Sample
void ParseString(String* str)
Char splitter[] = { ',' }; // This will cause link error
// Use the following instead
// Char splitter[] = new Char[1];
// splitter[0] = ',';