Refactoring returns by introducing booleans

Consider code that looks like:

1. void foo() {
2. if( some-condition ) return;
3. if( some-other-condition ) { do-something; return; }

etc.

Say this code is replicated in several places. Obviously we want to extract it into a common subroutine or class - the extract method refactoring.

If you can jump right to the end of the refactoring, great. But, I admit that I have occasionally tripped myself up doing this. (The example is, of course, oversimplified.)

So, here's a micro-refactoring that can help:

Extract to a function that returns a bool, named check_and_do_some_things_and_maybe_return()

1. void foo() {
2. if( check_and_do_somethings_and_maybe_return() ) return;
3. ...
   

1. bool check_and_do_somethings_and_maybe_return() {
   
2. if( some-condition ) return 1;
3. if( some-other-condition ) { do-something; return 1; }
4. return 0;
5. }
   

etc.

This requires editing each return.

If you want to avoid that, maybe add a boolean temporary to the original code - instead of returning immediately, delay all of the returns to

1. void foo() {
2. bool return_early = false;
   
3. if( some-condition ) return_early=true;
4. if( !return_early ) {
   
5. if( some-other-condition ) { do-something; return_early = true; }
6. if( !return_early ) ...
7. }
8. if( return_early ) return;

THEN you can safely extract the method a line or statement at a time.