start creating a subclass of command for producing a list of output in different formats, using prettytable as an example formatter

cliff/formatters/base.py

@@ -0,0 +1,26 @@
+"""Base classes for formatters.
+"""
+
+import abc
+
+
+class Formatter(object):
+
+    def __init__(self):
+        return
+
+    def add_argument_group(self, parser):
+        """Add any options to the argument parser.
+
+        Should use our own argument group.
+        """
+        return
+
+
+class ListFormatter(Formatter):
+    __metaclass__ = abc.ABCMeta
+
+    @abc.abstractmethod
+    def emit_list(self, column_names, data, stdout):
+        """Format and print the list from the iterable data source.
+        """

cliff/formatters/table.py

@@ -0,0 +1,46 @@
+"""Output formatters using prettytable.
+"""
+
+import prettytable
+
+from .base import ListFormatter
+
+
+class TableLister(ListFormatter):
+
+    ALIGNMENTS = {
+        int: 'r',
+        str: 'l',
+        unicode: 'l',
+        float: 'r',
+        }
+
+    def add_argument_group(self, parser):
+        group = parser.add_argument_group('Table Formatter')
+        group.add_argument(
+            '-c', '--column',
+            action='append',
+            default=[],
+            dest='columns',
+            help='specify the column(s) to include, can be repeated',
+            )
+
+    def emit_list(self, column_names, data, stdout, parsed_args):
+        x = prettytable.PrettyTable(column_names)
+        x.set_padding_width(1)
+        # Figure out the types of the columns in the
+        # first row and set the alignment of the
+        # output accordingly.
+        data_iter = iter(data)
+        first_row = next(data_iter)
+        for value, name in zip(first_row, column_names):
+            alignment = self.ALIGNMENTS.get(type(value), 'l')
+            x.set_field_align(name, alignment)
+        # Now iterate over the data and add the rows.
+        x.add_row(first_row)
+        for row in data_iter:
+            x.add_row(row)
+        formatted = x.get_string(fields=(parsed_args.columns or column_names))
+        stdout.write(formatted)
+        stdout.write('\n')
+        return

cliff/lister.py

@@ -0,0 +1,47 @@
+"""Application base class for providing a list of data as output.
+"""
+
+import pkg_resources
+
+from .command import Command
+
+
+class Lister(Command):
+    """Command base class for providing a list of data as output.
+    """
+
+    def __init__(self, app, app_args):
+        super(Lister, self).__init__(app, app_args)
+        self.load_formatter_plugins()
+
+    def load_formatter_plugins(self):
+        self.formatters = dict(
+            (ep.name, ep.load()())
+            for ep in pkg_resources.iter_entry_points('cliff.formatter.list')
+            )
+
+    def get_parser(self, prog_name):
+        parser = super(Lister, self).get_parser(prog_name)
+        formatter_group = parser.add_argument_group(
+            title='Output Formatters',
+            description='List output formatter options',
+            )
+        formatter_choices = sorted(self.formatters.keys())
+        formatter_default = formatter_choices[0]
+        formatter_group.add_argument(
+            '-f', '--format',
+            dest='formatter',
+            action='store',
+            choices=formatter_choices,
+            default=formatter_default,
+            help='the output format to use, defaults to %s' % formatter_default,
+            )
+        for name, formatter in sorted(self.formatters.items()):
+            formatter.add_argument_group(parser)
+        return parser
+
+    def run(self, parsed_args):
+        column_names, data = self.get_data(parsed_args)
+        formatter = self.formatters[parsed_args.formatter]
+        formatter.emit_list(column_names, data, self.app.stdout, parsed_args)
+        return 0

demoapp/cliffdemo/list.py

@@ -0,0 +1,16 @@
+import logging
+import os
+import stat
+
+from cliff.lister import Lister
+
+
+class Files(Lister):
+    "Show a list of files in the current directory."
+
+    log = logging.getLogger(__name__)
+
+    def get_data(self, parsed_args):
+        return (('Name', 'Size'),
+                ((n, os.stat(n).st_size) for n in os.listdir('.'))
+                )

demoapp/setup.py

@@ -164,6 +164,7 @@ setup(
             'simple = cliffdemo.simple:Simple',
             'two_part = cliffdemo.simple:Simple',
             'error = cliffdemo.simple:Error',
+            'files = cliffdemo.list:Files',
             ],
         # 'virtualenvwrapper.initialize': [
         #     'user_scripts = virtualenvwrapper.user_scripts:initialize',

setup.py

@@ -158,13 +158,9 @@ setup(
                                    ),
 
     entry_points={
-        # 'console_scripts': [
-        #     'venvw_hook = virtualenvwrapper.hook_loader:main'
-        #     ],
-        # 'virtualenvwrapper.initialize': [
-        #     'user_scripts = virtualenvwrapper.user_scripts:initialize',
-        #     'project = virtualenvwrapper.project:initialize',
-        #     ],
+        'cliff.formatter.list': [
+            'table = cliff.formatters.table:TableLister',
+            ],
         },
 
     zip_safe=False,