Extract function
The following demo illustrates the usage of the Extract function refactoring, as well as Extract parameter, Extract lambda parameter, and Live templates:
When the Extract Function refactoring is invoked, CLion analyzes 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.
Extract a function
In the editor, select a block of code to be transformed into a function.
From the main menu or from the context menu of the selection, select or press Ctrl+Alt+M.
In the Extract Function dialog that opens, specify the name of the new function, the return type, and other settings.
If the function has not been yet declared, select the declaration place: above or below current place.
In the parameters pane:
Add the new parameters or delete the unnecessary ones
Rename parameters or/and change their types by clicking the corresponding parameter lines and entering the new names and types
Reorder parameters in the list
Change the return type of the function
You can make a function
constexprornoexceptusing the corresponding checkboxes.Check the result in the Signature Preview pane and click Extract to create the function.
The selected code fragment will be replaced with a function call.
Before | After |
|---|---|
int main() {
int x = 15;
int y = 10;
int z = x - y;
return 0;
}
|
int main() {
int x = 10;
int y = 15;
int z = XSubY(x,y);
return 0;
}
void XSubY(int x, int y) { return x - y; }
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Code examples
Before | After |
|---|---|
private func setupUI() {
// ...
// This code will be extracted to a method
self.buttonLogin.layer.borderColor = UIColor.black.cgColor
self.buttonLogin.layer.borderWidth = 1.0
self.buttonLogin.setTitleColor(UIColor.black, for: .normal)
self.buttonLogin.setTitle("Login", for: .normal)
}
|
private func setupUI() {
// ...
// Extracted method's call
setupLoginButton()
}
// Extracted method
private func setupLoginButton() {
self.buttonLogin.layer.borderColor = UIColor.black.cgColor
self.buttonLogin.layer.borderWidth = 1.0
self.buttonLogin.setTitleColor(UIColor.black, for: .normal)
self.buttonLogin.setTitle("Login", for: .normal)
}
|
Before | After |
|---|---|
- (void)setupUI {
// ...
// This code will be extracted to a method
self.buttonLogin.layer.borderColor = [[UIColor blackColor] CGColor];
self.buttonLogin.layer.borderWidth = 1.0;
[self.buttonLogin setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[self.buttonLogin setTitle:@"Login" forState:UIControlStateNormal];
}
|
- (void)setupUI {
// ...
// Extracted method's call
[self setupLoginButton];
}
// Extracted method
- (void)setupLoginButton {
self.buttonLogin.layer.borderColor = [[UIColor blackColor] CGColor];
self.buttonLogin.layer.borderWidth = 1.0;
[self.buttonLogin setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[self.buttonLogin setTitle:@"Login" forState:UIControlStateNormal];
}
|