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Extract Function

What: Turn a fragment of code into its own function.

When: You have a fragment of existing code in some function that needs to be called from another function.

Why: You could copy/paste that code, but that would lead to duplication. A better solution is to refactor that fragment into its own function, which can be called by any other function.

How:

  1. Highlight the code to be extracted:

    Screenshot showing the following code that is highlighted prepartory to being extracted: double area = M_PI * readious * radious;.

  2. Next, do one of the following:

    • Keyboard
      • Press Ctrl+R, then Ctrl+M. (Your keyboard shortcut may be different depending on which profile you've selected.)
      • Press Ctrl+. to trigger the Quick Actions and Refactorings menu and select Extract Function (Experimental) from the context menu.
    • Mouse
      • Select Edit > Refactor > Extract Function (Experimental).
      • Right-click the code, select the Quick Actions and Refactorings menu and select Extract Function (Experimental) from the context menu.
      • Click the Lightbulb. icon that appears in the left margin and select Extract Function (Experimental) from the context menu.
  3. In the Extract Function/Method (Experimental) window, enter the new function name, select where you want the code to be placed, and click the OK button.

    Screenshot of the extract function dialog which takes the function name and whether to create it above or below the current function.

  4. The new function will be created where you specified, a function prototype in the corresponding header file, and the original code will be changed to call that function.

    Screenshot of the created function that contains the extracted code. The definition is void CalculateArea(double radius).