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How to translate this cpp code to golang ?
template<T> class CppTemp {
T a;
T* pa;
T foo(T &t);
};
template<T> T foo2(const T &t)
Go doesn't support templates or generics. There are three things you can do:
use non-empty interfaces where applicable
generate code with go generate
use interface{}:
type GoTemp struct {
a interface{}
}
func (gt *GoTemp) foo(v interface{}) {
// ...
}
func foo2(v interface{}) {
// ...
}
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I want to create a unique pointer in one class, class A, then pass on the ownership to another class, class B. Am I ok doing such a thing?
The code below gives me error in getC:
error: call to deleted constructor of 'std::unique_ptr<C>
What am I doing wrong?
class A {
...
void func(shared_ptr<B> Bptr) {
A_pass = make_unique<C>();
Bptr->setPass(move(A_pass));
}
unique_ptr<C> getC()
{
return A_pass;
}
unique_ptr<C> A_pass;
};
class B {
...
void setPass(unique_ptr<C> pass_ptr){
B_pass = move(pass_ptr);
}
unique_ptr<C> B_pass;
}
edit: update the question
Your question does not state where the compiler error occurs, but I would guess it’s the getC() member function:
class A {
...
unique_ptr<C> getC()
{
return A_pass;
}
unique_ptr<C> A_pass;
};
The function as written is attempting to copy A_pass, which of course is not possible for the std::unique_ptr<T> type.
You can rewrite it to explicitly move from the source (I’m not able to test this):
unique_ptr<C> A::getC() {
return A_pass.release();
// alternative: return unique_ptr<C>(std::move(A_pass));
}
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My main question is: can I put the generic type before a class definition?
Like, can I do something like this:
generic class Classname (ParameterType parameter)
{
cout << "Hello world";
}
Templates are the way to do generics in C++. You can write it like this:
template<class ItemType> class ClassName
{
public:
ClassName(const ItemType& newdata) : data(newdata) {}
private:
ItemType data;
};
Later on in main:
ClassName<int> data1(1);
ClassName<char> data2('A');
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I'm quite new to C++, and since I want my code to be good, I have a small question, let's say I have a function
UI::GetColor(CClass Class)
{
if (Class.m_Something)
return 0;
return 1;
}
Is it better to pass the CClass as a pointer, so it's not being copied or not? I saw a lot of code using different styles of that and I'm kind of confused which one is better and why. Thanks for answers.
The function should be written as follows:
class UI {
...
int GetColor(const CClass &c) const {
if (c.m_Something) {
return 0;
}
return 1;
}
}
The reference avoids an unnecessary copy; the const-parameter states that the parameter will not be changed; the const-function declarator states that the function will not change the this-object (i.e. the UI-instance on which it is called).
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I have an private property in my class and I want to add some code on its setter, how can I accomplish that?
I might do that using method but I don't want to just to avoid using property.
private:
float damage;
You can replace your plain old data type with a class type to do what you want:
class Damage
{
public:
Damage& operator=(float x) { value = x; /* add code here*/ }
operator float() const { return value; }
private:
float value;
};
Then just replace your float with Damage and you can make it behave how you want.
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I feel a bit confused about the default methods implementations in interfaces introduced in Java 8. I was wondering if we should write JUnit tests specifically for an interface and its implemented methods. I tried to google it, but I couldn't find some guidelines. Please advise.
Its depends on the method complexity. It is not really necessary if the code is trivial, for example:
public interface MyInterface {
ObjectProperty<String> ageProperty();
default String getAge() {
return ageProperty().getValue();
}
}
If the code is more complex, then you should write a unit test. For example, this default method from Comparator:
public interface Comparator<T> {
...
default Comparator<T> thenComparing(Comparator<? super T> other) {
Objects.requireNonNull(other);
return (Comparator<T> & Serializable) (c1, c2) -> {
int res = compare(c1, c2);
return (res != 0) ? res : other.compare(c1, c2);
};
}
...
}
How to test it?
Testing a default method from an interface is the same as testing an abstract class.
This has already been answered.