More cleanup suggested by @mhvk [skip ci]

taldcroft · taldcroft · commit a900297461fc · 2015-06-11T12:59:49.000-04:00
diff --git a/astropy/table/info.py b/astropy/table/info.py
@@ -20,7 +20,7 @@ def info(self, option='attributes', out=''):
     to include.  This can be a string, a function, or a list of
     strings or functions.  Built-in options are:
 
-    - ``meta``: basic column meta data like ``dtype`` or ``format``
+    - ``attributes``: basic column meta data like ``dtype`` or ``format``
     - ``stats``: basic statistics: minimum, mean, and maximum
 
     If a function is specified then that function will be called with the
@@ -73,11 +73,15 @@ def info(self, option='attributes', out=''):
 
     outlines = ['<' + ' '.join(descr_vals) + '>']
 
-    infos = []
-    for col in self.columns.values():
-        infos.append(col.info(option, out=None))
+    cols = self.columns.values()
+    if self.colnames:
+        infos = []
+        for col in cols:
+            infos.append(col.info(option, out=None))
 
-    info = Table(infos, names=list(infos[0]))
+        info = Table(infos, names=list(infos[0]))
+    else:
+        info = Table()
 
     if out is None:
         return info
@@ -88,12 +92,27 @@ def info(self, option='attributes', out=''):
         if np.all(info[name] == ''):
             del info[name]
 
-    if np.all(info['n_bad'] == 0):
+    if 'class' in info.colnames:
+        # Remove 'class' info column if all table columns are the same class
+        # and they are not mixin columns.
+        uniq_types = set(type(col) for col in cols)
+        if len(uniq_types) == 1 and not self._is_mixin_column(cols[0]):
+            del info['class']
+
+    if 'class' in info.colnames:
+        if np.all(info['class'] == 'Column') or np.all(info['class'] == 'MaskedColumn'):
+            del info['class']
+
+    if 'n_bad' in info.colnames and np.all(info['n_bad'] == 0):
         del info['n_bad']
 
     # Standard attributes has 'length' but this is typically redundant
     if 'length' in info.colnames and np.all(info['length'] == len(self)):
         del info['length']
 
-    outlines.extend(info.pformat(max_width=-1, max_lines=-1, show_unit=False))
+    if self.colnames:
+        outlines.extend(info.pformat(max_width=-1, max_lines=-1, show_unit=False))
+    else:
+        outlines.append('<No columns>')
+
     out.writelines(outline + os.linesep for outline in outlines)
diff --git a/astropy/table/tests/test_info.py b/astropy/table/tests/test_info.py
@@ -51,7 +51,7 @@ def test_table_info_attributes(table_types):
     assert np.all(tinfo['unit'] == ['', '', '', 'm', '', 'deg,deg'])
     assert np.all(tinfo['format'] == ['%02d', '', '', '', '', ''])
     assert np.all(tinfo['description'] == ['', '', '', 'quantity', 'time', 'skycoord'])
-    cls = 'MyColumn' if subcls else ''
+    cls = t.ColumnClass.__name__
     assert np.all(tinfo['class'] == [cls, cls, cls, cls, 'Time', 'SkyCoord'])
 
 def test_table_info_stats(table_types):
@@ -128,7 +128,7 @@ def test_data_info():
                                      ('unit', 'm / s'),
                                      ('format', ''),
                                      ('description', 'description'),
-                                     ('class', ''),
+                                     ('class', type(c).__name__),
                                      ('n_bad', 1),
                                      ('length', 3)])
 
@@ -139,6 +139,7 @@ def test_data_info():
                'dtype = float64',
                'unit = m / s',
                'description = description',
+               'class = {0}'.format(type(c).__name__),
                'n_bad = 1',
                'length = 3']
         assert out.getvalue().splitlines() == exp
@@ -163,16 +164,17 @@ class Column(table.Column):
         Confusingly named Column on purpose, but that is legal.
         """
         pass
-    c = Column([1, 2], dtype='int64')
-    cinfo = c.info(out=None)
-    assert cinfo == OrderedDict([('dtype', 'int64'),
-                                 ('shape', ''),
-                                 ('unit', ''),
-                                 ('format', ''),
-                                 ('description', ''),
-                                 ('class', 'Column'),
-                                 ('n_bad', 0),
-                                 ('length', 2)])
+    for data in ([], [1, 2]):
+        c = Column(data, dtype='int64')
+        cinfo = c.info(out=None)
+        assert cinfo == OrderedDict([('dtype', 'int64'),
+                                     ('shape', ''),
+                                     ('unit', ''),
+                                     ('format', ''),
+                                     ('description', ''),
+                                     ('class', 'Column'),
+                                     ('n_bad', 0),
+                                     ('length', len(data))])
 
 
 def test_scalar_info():
@@ -183,3 +185,11 @@ def test_scalar_info():
     cinfo = c.info(out=None)
     assert cinfo['n_bad'] == 0
     assert 'length' not in cinfo
+
+
+def test_empty_table():
+    t = table.Table()
+    out = six.moves.cStringIO()
+    t.info(out=out)
+    exp = ['<Table length=0>', '<No columns>']
+    assert out.getvalue().splitlines() == exp
diff --git a/astropy/utils/data_info.py b/astropy/utils/data_info.py
@@ -68,10 +68,8 @@ def _get_column_attribute(col, attr=None):
     """
     Get a column attribute for the ``attributes`` info summary method
     """
-    from ..table.column import Column, MaskedColumn
-
     if attr == 'class':
-        val = '' if type(col) in (Column, MaskedColumn) else type(col).__name__
+        val = type(col).__name__
     elif attr == 'dtype':
         val = col.info.dtype.name
     elif attr == 'shape':
