While studying the vim editor's test cases, I saw a command with a strange name; smile. Tested it and it was fun. Decided to study the source code of the vim to see how it works and then tried adding my own command to this superb editor; just for fun and practicing my C. We will see how professional programmers code, how we can compile that code and how we can even add to it.
00:00 - smile command in vim
01:30 - Studying vim source code in C
11:42 - Why C programmer look backward / decreasing
16:30 - compiling vim from source
19:25 - adding a new command to vim
p.s. I know.. there are some sound issues in this video :)