Allow setting the number of context lines in diff.conf

kittens/diff/config.py

@@ -49,6 +49,7 @@ def syntax_aliases(raw):
 
 type_map = {
     'syntax_aliases': syntax_aliases,
+    'num_context_lines': int,
 }
 
 for name in (

kittens/diff/diff.conf

@@ -9,6 +9,9 @@ syntax_aliases pyj:py recipe:py
 # for a list of schemes.
 pygments_style default
 
+# The number of lines of context to show around each change.
+num_context_lines 3
+
 # Colors
 foreground            black
 background            white

kittens/diff/main.py

@@ -50,7 +50,9 @@ class DiffHandler(Handler):
         self.report_traceback_on_exit = None
         self.args = args
         self.scroll_pos = self.max_scroll_pos = 0
-        self.current_context_count = self.args.context
+        self.current_context_count = self.original_context_count = self.args.context
+        if self.current_context_count < 0:
+            self.current_context_count = self.original_context_count = self.opts.num_context_lines
         self.highlighting_done = False
         self.restore_position = None
 
@@ -185,7 +187,7 @@ class DiffHandler(Handler):
                 if text == 'a':
                     new_ctx = 100000
                 elif text == '=':
-                    new_ctx = 3
+                    new_ctx = self.original_context_count
                 else:
                     new_ctx += (-1 if text == '-' else 1) * 5
                 self.change_context_count(new_ctx)
@@ -270,8 +272,9 @@ class DiffHandler(Handler):
 OPTIONS = partial('''\
 --context
 type=int
-default=3
+default=-1
-Number of lines of context to show between changes.
+Number of lines of context to show between changes. Negative values
+use the number set in diff.conf
 
 
 --config