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C++ overriding the value of inherited static const variables


C++ overriding the value of inherited static const variables

By : Scott
Date : November 21 2020, 03:00 PM
wish helps you You cannot change the value of constants as the name states const. You can only initialize them.
code :
class A{
    protected:
        static const int val1, val2, val3;
    public:
        void myMethod();
};

const int A::val1 = 9;
const int A::val2 = 5;
const int A::val3 = 4;


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Should single-use values be inline, function-level const variables, or class-level static const variables?

Should single-use values be inline, function-level const variables, or class-level static const variables?


By : user2763518
Date : March 29 2020, 07:55 AM
To fix this issue My personal preference:
Keep the literal as close to the point of use as possible - so options A or B, but not C.
code :
// option A
void MyType::parse(const wstring& input)
{
    if (input == L"QUIT") { quit(); }
    else if (input == L"CONTINUE") { read_next(); }
}

// option B
void MyType::parse(const wstring& input)
{
    static const wstring quit_command = L"*34!";
    static const wstring continue_command = L"*17!";

    if (input == quit_command) { quit(); }
    else if (input == continue_command) { read_next(); }
}
Trouble overwriting inherited static const members

Trouble overwriting inherited static const members


By : user2125575
Date : March 29 2020, 07:55 AM
I wish did fix the issue. I have two classes. The base class is fruit,and the derived class is apple. I use type strings to identify the type of the classes.However,when I tried to access the type() function of an instance of class apple to get the return of its type string, I got the base class' type string "fruit" rather than "apple".What should I do to fix this? Here's my code: , This cannot work.
code :
    std::string type();
#include <string>
class fruit
{
public:
    virtual ~fruit() = default;
    virtual const std::string& type(); // (return _typeStr)
private:
    static const std::string _typeStr;
}
const std::string fruit::_typeStr = "fruit";
std::string fruit::type()
{
    return _typeStr;
}
class apple:public fruit
{
public:
    const std::string& type() override; // (return _typeStr; will return apple::_typeStr)
private:
    static const std::string _typeStr;
}
const std::string apple::_typeStr = "apple";
C++ static const members overriding

C++ static const members overriding


By : yuesong jiang
Date : March 29 2020, 07:55 AM
This might help you You are going to need a template, and to change the inheritance to use the template, as you will see. The trick is to make it work whether the derived class has an X to overshadow the base-class X or not.
Objective-C using inherited variables & overriding inherited properties

Objective-C using inherited variables & overriding inherited properties


By : Yuriy Gupalo
Date : March 29 2020, 07:55 AM
With these it helps In your subclass, use the inherited accessors cardValue and setCardValue: to get and set the inherited value. You don't need to override the value; you just need to use it.
Once your subclass consistently uses the accessors, then you can override the accessors if you want. For example
Which is one better for static const char* or static const string for declaring static variables

Which is one better for static const char* or static const string for declaring static variables


By : lbudha133
Date : March 29 2020, 07:55 AM
it should still fix some issue Usually, std::string is good but in any case it depends on what you want to do. There is no absolute silver bullet here. std::string has a constructor and will call new/malloc for example (when SSO small string optimization can't be applied). If this is undesirable for any reason, go with const char*.
It depends also on where it 's to be used. If this is a HWND window title for example and the main use is with Windows API functions, it won't differ if you use std::string's c_str() method all the time.
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