To load a DLL and call function in VC++, we use LoadLibrary and GetProcAddress , which needs mangled name of the method. Does it instantiate a class object and then call the method?
If it does not then how can I call a method in a class but instantiating an object of the class and then call a method?
What is process to load .h file, load class, instantiate object and then call a method in VC++
There is actually a very good example on CodeProject that describes exactly how to do this.
EDIT with reference to your comment, if you read the above article, you'll see that GetProcAddress() does nothing more than return a function pointer. If you want to create an instance of a class that's exported from the DLL, you have to allocate memory and force the system to invoke the constructor of the class to instantiate it there. Once that's done, however, I'm sort of assuming that you can call functions defined in the class in the normal way by using the object you just created.
Related
I am new to Haxe and only plans to deploy for the web.
So I have a class A which has a method name doThis(). On class B, I inherited class A. I override doThis() on class B. When I check on the debugger, class A doThis() is being called and then class B doThis() is called as well.
My intuition is, I have overridden the methods explicitly and the only way I can call the parent is via a super.doThis() but it seems it does this automatically. I only want the version of doThis() to be B. Not A's.
Any thought on why it behaves like this? I think I a missing something here.
Thanks!
Without any further information, I'd bet good money that you have your debugger breakpoints on the definition of doThis, when you meant to put them in the invocation of doThis (inside the function body).
Other possible (but less likely) reasons:
A macro function is inserting a super.doThis() call
A modified Haxe compiler or JS generator is emitting a super.doThis() call.
Unless the function you are overriding is the constructor function new, calling the parent (super) function is optional. Furthermore, you can stipulate when the parent function is called by adjusting when you call super.doThis().
To illustrate, here is code that only runs the child classes function on try.haxe. It sounds like you may have already tried a similar approach, so ensure that you aren't missing some code that you may not be aware is calling the super function.
I think you're doing the right thing.
perhaps add some println to the parent function and the child function to make sure what you describe is what actually happens.
In other words, the debugger is not just playing with you.
I'd like to use a single duktape/C constructor function as dispatcher for these kind of calls. When the dispatcher function is called I need to know for which class this happend to call the appropriate C++ construction function.
I guess the this binding won't help since it represents the (not yet fully initialized) JS object we are creating here.
Another option would be the current function, but from the docs I can't see how to get the class name from that. What else could I use?
Could you elaborate what you mean by "class name"? Do you mean the .name property of the Ecmascript function object which is used as a the 'new' target?
If so, you can use duk_is_constructor_call() to see if the current call is a constructor call, then use duk_push_current_function() to get access to the Ecmascript constructor function object, and then read its properties using the usual property API calls. For example, if by "class name" you mean .name of the function object, you'd just read its "name" property using duk_get_prop_string().
I have a Node class which I import in many of my projects modules Once imported into required module I create object of it and then call related methods of that object.
My question is how do I get the object caller's file name in my class file without explicitly passing so
I don't want to use module.parent.filename as it only gives the file name of parent file and not of other files. After some R&D I came to know that there is a module called stack-trace which could provide me similar functionality. But when I tried following code into my class I got the name of file itself in which the code was written and not the name of file which was calling the object of that class
const stackTrace = require('stack-trace');
var trace = stackTrace.get()
console.log(trace[0].getFileName())
The manual states, for stackTrace.get():
Returns an array of CallSite objects, where element 0 is the current call site.
You don't want the current call site, but the previous one, so you need to use trace[1].getFileName()
I am trying to mock a call to a protected method of one of my classes:
import com.couchbase.client.java.view.Stale; // an enum
import com.google.common.base.Optional;
public class MyClass {
public List<String> myList(Optional<Integer> arg1, Optional<Stale> arg2) {
...
}
}
The mock shall be accomplished in the following way:
// Providing types for any() does not change anything
Mockito.when(myClass.myList(Mockito.any(), Mockito.any()).thenReturn(new ArrayList());
Whenever the previous line is executed the actual myList() method is called with null values for arg1 and arg2. Why is the method called, at all? After all, I am trying to avoid any executing thereof...
As Brice mentioned, if your myList method is final, then Java skips virtual method dispatch and will call the original object (not your mock).
If you are spying on an actual class, it is expected behavior that when will call the actual object as part of the stub: after all, in the expression when(foo.bar()) Java doesn't know anything special about when and assumes that it cares about the return value) of foo.bar(), not the call itself. (I walk through the stubbing process in the "Implementation details" section of my answer here.)
This syntax is better for spies:
doReturn(new ArrayList()).when(myClass).myList(any(), any());
Because this different when method receives an object, Mockito can prepare the object to do nothing during the stubbing, which avoids any spurious calls to your myList method.
Although Jeff's answer did not show a workaround for my problem it pointed me into the right direction.
After changing the mocking behaviour to doReturn... I suddenly got an error message. This message told me that myClass is not a mock which makes sense since you can only mock (or stub?) methods of mocked or spied objects. So as Jeff's answer indicates and is explained in the documentation of mockito I created a partial mock of MyClass with
MyClass myClass = Mockito.spy(new MyClass());
With this partial mock Jeff's approach to method mocking suddenly worked (mine still does not and should therefore be avoided).
So: Thank you, Jeff!
How do you define a non-default constructor for a COM object in Visual C++?
Is such a thing even possible?
Or do you have to construct a default object and use an init(params) method to configure it?
COM coclasses implemented in C++ cannot have a constructor that takes an argument. The CoCreateObject() function, the primary way to create an instance of a coclass, doesn't have any way to pass arguments. Same with IClassFactory::CreateInstance(), the underlying method.
So yes, not possible, you'll need an Initialize() method. And the code to verify that it was called, E_UNEXPECTED with a decent IErrorInfo message is boilerplate.