Refactor DisplayBase.run() to make it easier to override separate parts in subclasses.

Rename get_data() to take_action() so subclasses that do something other than query for values have a clear place to override.

5 files changed, 27 insertions, 16 deletions

diff --git a/cliff/display.py b/cliff/display.py
index 2d9a7f7..6d9f522 100644
--- a/cliff/display.py
+++ b/cliff/display.py
@@ -70,14 +70,23 @@ class DisplayCommandBase(Command):
         return parser
 
     @abc.abstractmethod
-    def get_data(self, parsed_args):
+    def take_action(self, parsed_args):
         """Return a two-part tuple with a tuple of column names
         and a tuple of values.
         """
 
     @abc.abstractmethod
+    def produce_output(self, parsed_args, column_names, data):
+        """Use the formatter to generate the output.
+
+        :param parsed_args: argparse.Namespace instance with argument values
+        :param column_names: sequence of strings containing names
+                             of output columns
+        :param data: iterable with values matching the column names
+        """
+
     def run(self, parsed_args):
-        column_names, data = self.get_data(parsed_args)
-        formatter = self.formatters[parsed_args.formatter]
-        formatter.emit_one(column_names, data, self.app.stdout, parsed_args)
+        column_names, data = self.take_action(parsed_args)
+        self.formatter = self.formatters[parsed_args.formatter]
+        self.produce_output(parsed_args, column_names, data)
         return 0
diff --git a/cliff/lister.py b/cliff/lister.py
index abf3771..c3fb909 100644
--- a/cliff/lister.py
+++ b/cliff/lister.py
@@ -24,13 +24,12 @@ class Lister(DisplayCommandBase):
         return 'table'
 
     @abc.abstractmethod
-    def get_data(self, parsed_args):
+    def take_action(self, parsed_args):
         """Return a tuple containing the column names and an iterable
         containing the data to be listed.
         """
 
-    def run(self, parsed_args):
-        column_names, data = self.get_data(parsed_args)
+    def produce_output(self, parsed_args, column_names, data):
         if not parsed_args.columns:
             columns_to_include = column_names
             data_gen = data
@@ -50,6 +49,8 @@ class Lister(DisplayCommandBase):
             # list so the table formatter can ask for its length.
             data_gen = (list(itertools.compress(row, selector))
                         for row in data)
-        formatter = self.formatters[parsed_args.formatter]
-        formatter.emit_list(columns_to_include, data_gen, self.app.stdout, parsed_args)
+        self.formatter.emit_list(columns_to_include,
+                                 data_gen,
+                                 self.app.stdout,
+                                 parsed_args)
         return 0
diff --git a/cliff/show.py b/cliff/show.py
index 34af0b4..39e94b1 100644
--- a/cliff/show.py
+++ b/cliff/show.py
@@ -24,13 +24,12 @@ class ShowOne(DisplayCommandBase):
         return 'table'
 
     @abc.abstractmethod
-    def get_data(self, parsed_args):
+    def take_action(self, parsed_args):
         """Return a two-part tuple with a tuple of column names
         and a tuple of values.
         """
 
-    def run(self, parsed_args):
-        column_names, data = self.get_data(parsed_args)
+    def produce_output(self, parsed_args, column_names, data):
         if not parsed_args.columns:
             columns_to_include = column_names
         else:
@@ -40,6 +39,8 @@ class ShowOne(DisplayCommandBase):
             selector = [(c in columns_to_include)
                         for c in column_names]
             data = list(itertools.compress(data, selector))
-        formatter = self.formatters[parsed_args.formatter]
-        formatter.emit_one(columns_to_include, data, self.app.stdout, parsed_args)
+        self.formatter.emit_one(columns_to_include,
+                                data,
+                                self.app.stdout,
+                                parsed_args)
         return 0
diff --git a/demoapp/cliffdemo/list.py b/demoapp/cliffdemo/list.py
index 124997f..3dcee4a 100644
--- a/demoapp/cliffdemo/list.py
+++ b/demoapp/cliffdemo/list.py
@@ -12,7 +12,7 @@ class Files(Lister):
 
     log = logging.getLogger(__name__)
 
-    def get_data(self, parsed_args):
+    def take_action(self, parsed_args):
         return (('Name', 'Size'),
                 ((n, os.stat(n).st_size) for n in os.listdir('.'))
                 )
diff --git a/demoapp/cliffdemo/show.py b/demoapp/cliffdemo/show.py
index 54d98be..9351148 100644
--- a/demoapp/cliffdemo/show.py
+++ b/demoapp/cliffdemo/show.py
@@ -14,7 +14,7 @@ class File(ShowOne):
         parser.add_argument('filename', nargs='?', default='.')
         return parser
 
-    def get_data(self, parsed_args):
+    def take_action(self, parsed_args):
         stat_data = os.stat(parsed_args.filename)
         columns = ('Name',
                    'Size',