I want to extend CMFCRibbonPanel - but the constructor is protected (I get the following error: cannot access protected member declared in class 'CMFCRibbonPanel'). The only way to obtain a CMFCRibbonPanel instance is by calling "category->AddPanel", but this way I cannot extend the CMFCRibbonPanel class.
Any suggestions?
A protected constructor is accessible from within the derived class.
My guess is that your derived class CTor is protected, too.
If you make it public, that should work.
Related
Please don't close as duplicate. I know there are multiple threads on this topic but none of them answers my question.
I am still struggling to understand why do we need Cloneable interface in java. If we want to create copy of an object, we can simply override clone method from Object class and call super.clone().
Since clone method in Object class is native, we don't know if the native implementation checks for instanceOf Cloneable and then create a copy else throw CloneNotSupportedException.
I know it's not a good practice to override clone() method to create a copy and should go for copy constructor instead, but still I want to know is the existence of Cloneable marker interface justified.
Whether an object implements Cloneable or not only matters if the built-in Object.clone() method is called (probably by some method in your class that calls super.clone()). If the built-in Object.clone() method is called, and the object does not implement Cloneable, it throws a CloneNotSupportedException. You say "we don't know" whether the Object.clone() method does that -- we do -- the documentation for Object.clone() method in the Java class library explicitly promises it, and it describes in detail the cloning operation that the method performs.
If you implement a cloning method that does not call up to Object.clone(), then whether the object implements Cloneable or not has no effect.
As it commonly known, one cannot extend or redefine interface of the overridden method in the inherited ABAP class. Help:
The interface and the category of the method (a general or functional instance method or event handler) are not changed in a redefinition.
This covers both global and local classes redefinition.
What are the probable workarounds of this limitation if one wants to add or remove methods parameters or change their type? Optional parameters is a way, though not very comfy. Any other ways?
You cannot change the signature of an interface method in any way in its implementations. This is simply because there is no way to do this that would not produce hard-to-analyze syntax errors at run time. An interface is a contract - any class implementing it promises that it will implement all methods (and variables...) that are present in the interface.
Assume there is a method METH of interface IF1 taking a single parameter PAR1 of type TYPE1. If you now write a class that implements a method METH with a single parameter PAR1 of type TYPE2, then you have not written a class that implements IF1. A caller that passes a parameter of type TYPE1 to the method of your class will encounter a type conversion error (whether at runtime or at compile time depends somewhat on the genericity of the types).
Therefore, there is no way to change the signature of an interface method in its redefinition without producing such runtime errors - your class does not implement the interface. Implementing an interface means that the class will accept exactly the number, type and kind of parameters specified for the methods in the interface. There is literally no use case in which you could meaningfully want to change this while still claiming that your class implements the interface. Whatever you're trying to do, this isn't the solution.
You can create your own interface, extending the existing interface. Add same method with different parameters. Then create abstract class from your extended interface and fill methods with code for calling real method with setting values to optional parameters. After then create your class from abstract.
interface
|--> extented interface
|--> abstract class
|--> class
I have a class called Awesome and have used the ServiceProvider and the Facade to register it to the app. Now I can use it as Awesome::Things().
I want to add constants to this class, so I tried
<?php namespace Helper\Awesome;
class Awesome()
{
public static $MOVIE = 'I love the Lego Movie!";
}
but when I call Awesome::$MOVIE, I get Access to undeclared static property: Helper\\Aesome\\Facades\\AwesomeFacade::$MOVIE
Can someone help?
The short version is -- you don't really want to do that. Laravel facades aren't mean to be used like normal classes, and if your application uses them that way you'll likely confuse future developers.
Warning out of the way. When you create a "facade" in Laravel, you're actually creating a class alias. When you added Awesome to the alias list in app/config/app.php, at some point code like the following ran
class_alias('Helper\Aesome\Facades\AwesomeFacade','Awesome');
That means whenever you use a global non-namespaced class Awesome, PHP substitutes Helper\Aesome\Facades\AwesomeFacade. If you wanted to add constants, you'd need to add them to this class.
Laravel's able to pass through methods because of the base Facade class implements a __callStatic method that passes on your call to the actual service implementation object. Facades don't pass on static constant access. Additionally, PHP does not (appear to?) have similar magic methods for passing along requests for constants.
If you're curious about the in depth version of this answer, I'm currently writing a series on Laravel's object system, including some in-depth information about the facade implementation.
I'm trying to make an object that is created and deleted using a factory visible to python.
The object has private constructor and destructor, and the factory lifetime must be bigger than the object it creates.
It seems like the following code should do it:
class_<Factory>("Factory")
.def("CreateObject", &Factory::CreateObject,
return_internal_reference<1, return_value_policy<manage_new_object>>());
class_<Object, boost::noncopyable>("Object", no_init);
And it does so with no compiler or runtime errors as far as I can tell.
The problem is how does boost know how to destroy the object?
I specified manage_new_object so it needs to destroy it, but it cannot call the destructor since its private and I haven't provided it with the name of the factory destruction method.
How can I specify it? I can add another def to Factory but that would mean python code will have to deal with destruction of object and can have dangling objects.
What I want to do is when this object's reference count reaches 0, either factory.DestroyObject(object) will be automatically called or even a static function I provide with only the object as argument will be called (the factory can be recovered from the object).
In my constructor of a class, I call a virtual member. Whether this should or should not be done is out of scope for my question.
WORKS (can call in my constructor):
protected void DoSomething();
protected virtual void DoSomething();
DOES NOT WORK
protected override void DoSomething();
The DOES NOT WORK part is located in the same library, the derived class has the same visibility, etc. As soon as I override the (virtual or abstract) DoSomething defined in class A in my Class B, I get a MissingMethodException as soon as the method is executed.
Does anyone have an idea why?
After lots of debugging, trying, etc, it seems that a class I used inside the method derived from an interface with this definition:
public interface IMyInterface<out TValueInterface>
It seems you cannot use covariant type parameters, otherwise you will get this exception.
For more information, see this blog post.
I think it's because you created the project with the beta 1 of the SDK.
Try again in a new project and you won't encounter the problem :-p !