DIY_GIT_in_Python/how_to/Change_25.md

• cli: pass HEAD by default in argparse

First, make “@” be an alias for HEAD. (Implemented in get_oid)

Second, do a little refactoring in cli.py. Some commands accept an optional OID argument and if the argument isn’t provided it defaults to HEAD. For example git log can get an OID to start logging from, but by default it logs all commits before HEAD.

Instead of having each command implement this logic, let’s just make “@” (HEAD) be the default value for those commands. The relevant commands at this stage are log and tag. More will follow.