CLion 2023.1 Help

Extract superclass

The Extract Superclass refactoring enables extracting certain members of a class into a superclass. In CLion, this refactoring is available for C++, Objective-C/C++, Python and JavaScript code.




class SomeClass { char SomeChar = 'a'; long d22; //This function will be extracted to a base class void exFunc(int); };
class SuperClass { void exFunc(int); }; class SomeClass : public SuperClass { char SomeChar = 'a'; long d22; };



@interface SClass : NSObject { int v; //This variable will be extracted to a superclass } - (void)initV; @end @implementation SClass - (void)initV { v = 20; } @end
@interface SuperClass : NSObject { int v; } @end @interface SClass : SuperClass - (void)initV; @end @implementation SClass - (void)initV { v = 20; } @end



class BaseClass: # This function will be extracted to a base class def eval_smth(self, a, b, c): x = 2*b - c y = 2*b + c return x, y
class SuperClass: def eval_smth(self, a, b, c): x = 2*b - c y = 2*b + c return x, y class BaseClass(SuperClass): pass



class Editor { //This function will be extracted to a superclass View() { console.log( + ' can view'); } Edit() { console.log( + ' can edit'); } }
class User { View() { console.log( + ' can view'); } } class Editor extends User { Edit() { console.log( + ' can edit'); } }

Extract a superclass

  1. Select the desired class in one of the views, or just open it in the editor.

  2. Choose Refactor | Extract/Introduce | Superclass from the main menu or Refactor | Extract Superclass from the context menu.

  3. In the Extract Superclass dialog that appears, specify the following information:

    • Name of the new superclass in the Extract superclass from field.

    • Members to be included in the superclass

      Extract Superclass dialog

    The Extract superclass from field displays the name of the class, from which a superclass should be extracted. It is read-only.

  4. Click Refactor to proceed with the refactoring. The superclass is created and the original class is modified to inherit from it:

Extracting the class dependent members

Let's consider the following sample of code:

int d1; class XClass { static const int d2 = 13; int exRes = d2 * d1; };

As you can see, there is a dependency between d1 and exRes. If you apply Extract Superclass refactoring to the above class and try to select exRes to be moved, CLion highlights the d2 variable with blue:

highlighted variable

Trying to proceed with extract, you will get the following warning message:

warning message

Choose Continue to ignore the problem and proceed with refactoring, or Cancel to return back and resolve it. Also you can observe the conflict in Find Tool Window.

Last modified: 25 April 2023