pass HEAD by default to argparse

how_to/Change_25.md

@@ -0,0 +1,12 @@
+- 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.

ugit/base.py

@@ -130,6 +130,9 @@ def get_commit(oid):
 
 
 def get_oid(name):
+    if name == "@":
+        name = "HEAD"
+
     # Name is ref
     refs_to_try = [
         f"{name}",

ugit/cli.py

@@ -45,7 +45,7 @@ def parse_args():
 
     log_parser = commands.add_parser("log")
     log_parser.set_defaults(func=log)
-    log_parser.add_argument("oid", type=oid, nargs="?")
+    log_parser.add_argument("oid", default="@", type=oid, nargs="?")
 
     checkout_parser = commands.add_parser("checkout")
     checkout_parser.set_defaults(func=checkout)
@@ -54,7 +54,7 @@ def parse_args():
     tag_parser = commands.add_parser("tag")
     tag_parser.set_defaults(func=tag)
     tag_parser.add_argument("name")
-    tag_parser.add_argument("oid", type=oid, nargs="?")
+    tag_parser.add_argument("oid", default="@", type=oid, nargs="?")
 
     return parser.parse_args()
 
@@ -87,7 +87,7 @@ def commit(args):
 
 
 def log(args):
-    oid = args.oid or data.get_ref("HEAD")
+    oid = args.oid
     while oid:
         commit = base.get_commit(oid)
 
@@ -103,5 +103,4 @@ def checkout(args):
 
 
 def tag(args):
-    oid = args.oid or data.get_ref("HEAD")
-    base.create_tag(args.name, oid)
+    base.create_tag(args.name, args.oid)