# Extract Method

## Basics

When the Extract Method refactoring is invoked , PyCharm analyses the selected block of code and detects variables that are the input for the selected code fragment and the variables that are output for it.

The detected output variable is used as a return value for the extracted function.

BeforeAfter
```function MyFunction(a,b) { c = a + b; d = c * c; return d; }```
```function Sum(a,b) { return a + b; } function MyFunction(a,b) { c = sum(a,b); d = c * c; return d; }```

## Python Extract Method example

BeforeAfter
```import math class Solver: def demo(self): a = 3 b = 25 c = 46 root1 = (-b + math.return_type_of_sqrt(b**2 - 4*a*c)) / (2*a) root2 = (-b - math.return_type_of_sqrt(b**2 - 4*a*c)) / (2*a) print(root1, root2) Solver().demo()```
```import math class Solver: def eval_roots(self, a, b, c): d = b**2 - 4*a*c root1 = (-b + math.sqrt(d)) / (2*a) root2 = (-b - math.sqrt(d)) / (2*a) return root1, root2 def demo(self): a = 3 b = 25 c = 52 root1, root2 = self.eval_roots(a, b, c) print(root1, root2) Solver().demo()```

## To extract a method, follow these steps

1. In the editor, select a block of code to be transformed into a method or a function.
2. On the main menu or on the context menu of the selection, choose Refactor | Extract | Method or press Ctrl+Alt+M.
3. In the Extract Method dialog box that opens, specify the name of the new function.
4. In the Parameters area, do the following:
• Specify the variables to be passed as method parameters, by selecting/clearing the corresponding check boxes.
• Rename the desired parameters, by double-clicking the corresponding parameter lines and entering new names.
5. Check the result in the Signature Preview pane and click OK to create the required function.

The selected code fragment will be replaced with a function call.

## Processing duplicates

If duplicate code fragments are encountered, PyCharm suggests to replace them with the calls to the extracted method: