Change __str__ to render

We'll want to pass in arguments to render (i.e., width),
so using __str__ is not going to be appropriate.

28 files changed, 78 insertions, 75 deletions

diff --git a/ttystatus/bytesize.py b/ttystatus/bytesize.py
index 4c338aa..b5a8059 100644
--- a/ttystatus/bytesize.py
+++ b/ttystatus/bytesize.py
@@ -28,7 +28,7 @@ class ByteSize(ttystatus.Widget):
     def update(self, ts):
         self._bytes = ts[self.name]
         
-    def __str__(self):
+    def render(self):
         units = (
             (1024**4, 2, 'TiB'),
             (1024**3, 2, 'GiB'),
diff --git a/ttystatus/bytesize_tests.py b/ttystatus/bytesize_tests.py
index d1dd94d..e6ce761 100644
--- a/ttystatus/bytesize_tests.py
+++ b/ttystatus/bytesize_tests.py
@@ -25,33 +25,33 @@ class ByteSizeTests(unittest.TestCase):
         self.w = ttystatus.ByteSize('foo')
 
     def test_formats_zero_bytes_without_update(self):
-        self.assertEqual(str(self.w), '0 B')
+        self.assertEqual(self.w.render(), '0 B')
 
     def test_formats_zero_bytes_correctly(self):
         self.w.update({ 'foo': 0 })
-        self.assertEqual(str(self.w), '0 B')
+        self.assertEqual(self.w.render(), '0 B')
 
     def test_formats_one_bytes_correctly(self):
         self.w.update({ 'foo': 1 })
-        self.assertEqual(str(self.w), '1 B')
+        self.assertEqual(self.w.render(), '1 B')
 
     def test_formats_1023_bytes_correctly(self):
         self.w.update({ 'foo': 1023 })
-        self.assertEqual(str(self.w), '1023 B')
+        self.assertEqual(self.w.render(), '1023 B')
 
     def test_formats_1024_bytes_correctly(self):
         self.w.update({ 'foo': 1024 })
-        self.assertEqual(str(self.w), '1.0 KiB')
+        self.assertEqual(self.w.render(), '1.0 KiB')
 
     def test_formats_1_MiB_bytes_correctly(self):
         self.w.update({ 'foo': 1024**2 })
-        self.assertEqual(str(self.w), '1.00 MiB')
+        self.assertEqual(self.w.render(), '1.00 MiB')
 
     def test_formats_1_GiB_bytes_correctly(self):
         self.w.update({ 'foo': 1024**3 })
-        self.assertEqual(str(self.w), '1.00 GiB')
+        self.assertEqual(self.w.render(), '1.00 GiB')
 
     def test_formats_1_TiB_bytes_correctly(self):
         self.w.update({ 'foo': 1024**4 })
-        self.assertEqual(str(self.w), '1.00 TiB')
+        self.assertEqual(self.w.render(), '1.00 TiB')
 
diff --git a/ttystatus/bytespeed.py b/ttystatus/bytespeed.py
index cc62300..d7e8b78 100644
--- a/ttystatus/bytespeed.py
+++ b/ttystatus/bytespeed.py
@@ -33,7 +33,7 @@ class ByteSpeed(ttystatus.Widget):
         
         return time.time()
         
-    def __str__(self):
+    def render(self):
         units = (
             (1024**4, 2, 'TiB/s'),
             (1024**3, 2, 'GiB/s'),
diff --git a/ttystatus/bytespeed_tests.py b/ttystatus/bytespeed_tests.py
index 369c2f6..b56afc3 100644
--- a/ttystatus/bytespeed_tests.py
+++ b/ttystatus/bytespeed_tests.py
@@ -25,30 +25,30 @@ class ByteSpeedTests(unittest.TestCase):
         self.w = ttystatus.ByteSpeed('foo')
 
     def test_formats_zero_speed_without_update(self):
-        self.assertEqual(str(self.w), '0 B/s')
+        self.assertEqual(self.w.render(), '0 B/s')
 
     def test_formats_zero_bytes_correctly(self):
         self.w.update({ 'foo': 0 })
-        self.assertEqual(str(self.w), '0 B/s')
+        self.assertEqual(self.w.render(), '0 B/s')
 
     def test_formats_one_byte_per_second_correctly(self):
         self.w.now = lambda: 1
         self.w.update({ 'foo': 0 })
         self.w.now = lambda: 2
         self.w.update({ 'foo': 1 })
-        self.assertEqual(str(self.w), '1 B/s')
+        self.assertEqual(self.w.render(), '1 B/s')
 
     def test_formats_ten_bytes_per_second_correctly(self):
         self.w.now = lambda: 1
         self.w.update({ 'foo': 0 })
         self.w.now = lambda: 11
         self.w.update({ 'foo': 100 })
-        self.assertEqual(str(self.w), '10 B/s')
+        self.assertEqual(self.w.render(), '10 B/s')
 
     def test_formats_ten_tibs_per_second_correctly(self):
         self.w.now = lambda: 1
         self.w.update({ 'foo': 0 })
         self.w.now = lambda: 2
         self.w.update({ 'foo': 10 * 1024**4 })
-        self.assertEqual(str(self.w), '10.00 TiB/s')
+        self.assertEqual(self.w.render(), '10.00 TiB/s')
 
diff --git a/ttystatus/counter.py b/ttystatus/counter.py
index 5b92791..ae61fa0 100644
--- a/ttystatus/counter.py
+++ b/ttystatus/counter.py
@@ -26,7 +26,7 @@ class Counter(ttystatus.Widget):
         self.prev = None
         self.count = 0
 
-    def __str__(self):
+    def render(self):
         return str(self.count)
         
     def update(self, master):
diff --git a/ttystatus/counter_tests.py b/ttystatus/counter_tests.py
index f7dc3e1..638de6a 100644
--- a/ttystatus/counter_tests.py
+++ b/ttystatus/counter_tests.py
@@ -25,19 +25,19 @@ class CounterTests(unittest.TestCase):
         self.w = ttystatus.Counter('foo')
 
     def test_counts_zero_initially(self):
-        self.assertEqual(str(self.w), '0')
+        self.assertEqual(self.w.render(), '0')
 
     def test_counts_one_change(self):
         self.w.update({ 'foo': 'a' })
-        self.assertEqual(str(self.w), '1')
+        self.assertEqual(self.w.render(), '1')
 
     def test_counts_two_changes(self):
         self.w.update({ 'foo': 'a' })
         self.w.update({ 'foo': 'b' })
-        self.assertEqual(str(self.w), '2')
+        self.assertEqual(self.w.render(), '2')
 
     def test_does_not_count_if_value_does_not_change(self):
         self.w.update({ 'foo': 'a' })
         self.w.update({ 'foo': 'a' })
-        self.assertEqual(str(self.w), '1')
+        self.assertEqual(self.w.render(), '1')
 
diff --git a/ttystatus/elapsed.py b/ttystatus/elapsed.py
index 242c092..3a85303 100644
--- a/ttystatus/elapsed.py
+++ b/ttystatus/elapsed.py
@@ -31,7 +31,7 @@ class ElapsedTime(ttystatus.Widget):
         '''Wrapper around time.time() for unit tests to override.'''
         return time.time()
 
-    def __str__(self):
+    def render(self):
         secs = self.secs
         hours = secs / 3600
         secs %= 3600
diff --git a/ttystatus/elapsed_tests.py b/ttystatus/elapsed_tests.py
index 9c82acb..3197a77 100644
--- a/ttystatus/elapsed_tests.py
+++ b/ttystatus/elapsed_tests.py
@@ -25,17 +25,17 @@ class ElapsedtimeTests(unittest.TestCase):
         self.w = ttystatus.ElapsedTime()
 
     def test_shows_zero_initially(self):
-        self.assertEqual(str(self.w), '00h00m00s')
+        self.assertEqual(self.w.render(), '00h00m00s')
 
     def test_shows_zero_after_first_update(self):
         self.w.get_time = lambda: 1
         self.w.update({})
-        self.assertEqual(str(self.w), '00h00m00s')
+        self.assertEqual(self.w.render(), '00h00m00s')
 
     def test_shows_one_one_one_after_second_update(self):
         self.w.get_time = lambda: 0
         self.w.update({})
         self.w.get_time = lambda: 60*60 + 60 + 1
         self.w.update({})
-        self.assertEqual(str(self.w), '01h01m01s')
+        self.assertEqual(self.w.render(), '01h01m01s')
 
diff --git a/ttystatus/fmt_tests.py b/ttystatus/fmt_tests.py
index af39948..422a7fe 100644
--- a/ttystatus/fmt_tests.py
+++ b/ttystatus/fmt_tests.py
@@ -32,13 +32,13 @@ class FormatTests(unittest.TestCase):
         x = ttystatus.fmt.parse('hello, world')
         self.assertEqual(len(x), 1)
         self.assertEqual(type(x[0]), ttystatus.Literal)
-        self.assertEqual(str(x[0]), 'hello, world')
+        self.assertEqual(x[0].render(), 'hello, world')
 
     def test_parses_escaped_pecent(self):
         x = ttystatus.fmt.parse('%%')
         self.assertEqual(len(x), 1)
         self.assertEqual(type(x[0]), ttystatus.Literal)
-        self.assertEqual(str(x[0]), '%')
+        self.assertEqual(x[0].render(), '%')
 
     def test_parses_parameterless_widget(self):
         x = ttystatus.fmt.parse('%ElapsedTime()')
@@ -60,12 +60,12 @@ class FormatTests(unittest.TestCase):
         self.assertEqual(len(x), 4)
 
         self.assertEqual(type(x[0]), ttystatus.Literal)
-        self.assertEqual(str(x[0]), 'hello, ')
+        self.assertEqual(x[0].render(), 'hello, ')
 
         self.assertEqual(type(x[1]), ttystatus.String)
 
         self.assertEqual(type(x[2]), ttystatus.Literal)
-        self.assertEqual(str(x[2]), ': ')
+        self.assertEqual(x[2].render(), ': ')
 
         self.assertEqual(type(x[3]), ttystatus.ElapsedTime)
 
diff --git a/ttystatus/index.py b/ttystatus/index.py
index daa13df..3e73502 100644
--- a/ttystatus/index.py
+++ b/ttystatus/index.py
@@ -27,7 +27,7 @@ class Index(ttystatus.Widget):
         self.value = None
         self.listvalue = []
         
-    def __str__(self):
+    def render(self):
         try:
             index = self.listvalue.index(self.value) + 1
         except ValueError:
diff --git a/ttystatus/index_tests.py b/ttystatus/index_tests.py
index d3d420e..05d2db7 100644
--- a/ttystatus/index_tests.py
+++ b/ttystatus/index_tests.py
@@ -25,13 +25,13 @@ class IndexTests(unittest.TestCase):
         self.w = ttystatus.Index('foo', 'foos')
 
     def test_is_zero_initially(self):
-        self.assertEqual(str(self.w), '0/0')
+        self.assertEqual(self.w.render(), '0/0')
         
     def test_gets_index_right(self):
         self.w.update({ 'foo': 'x', 'foos': ['a', 'x', 'b'] })
-        self.assertEqual(str(self.w), '2/3')
+        self.assertEqual(self.w.render(), '2/3')
         
     def test_handles_value_not_in_list(self):
         self.w.update({ 'foo': 'xxx', 'foos': ['a', 'x', 'b'] })
-        self.assertEqual(str(self.w), '0/3')
+        self.assertEqual(self.w.render(), '0/3')
 
diff --git a/ttystatus/integer.py b/ttystatus/integer.py
index 1b27126..7def9ff 100644
--- a/ttystatus/integer.py
+++ b/ttystatus/integer.py
@@ -25,7 +25,7 @@ class Integer(ttystatus.Widget):
         self._key = key
         self.value = None
 
-    def __str__(self):
+    def render(self):
         try:
             return str(int(self.value))
         except (TypeError, ValueError):
diff --git a/ttystatus/integer_tests.py b/ttystatus/integer_tests.py
index f5b3f54..9ea8054 100644
--- a/ttystatus/integer_tests.py
+++ b/ttystatus/integer_tests.py
@@ -25,13 +25,13 @@ class IntegerTests(unittest.TestCase):
         self.w = ttystatus.Integer('foo')
 
     def test_is_error_initially(self):
-        self.assertEqual(str(self.w), '#')
+        self.assertEqual(self.w.render(), '#')
         
     def test_updates(self):
         self.w.update({'foo': 123})
-        self.assertEqual(str(self.w), '123')
+        self.assertEqual(self.w.render(), '123')
         
     def test_becomes_error_symbol_if_value_is_not_integer(self):
         self.w.update({'foo': 'bar'})
-        self.assertEqual(str(self.w), '#')
+        self.assertEqual(self.w.render(), '#')
 
diff --git a/ttystatus/literal.py b/ttystatus/literal.py
index d0a1dc7..fa09ceb 100644
--- a/ttystatus/literal.py
+++ b/ttystatus/literal.py
@@ -24,5 +24,5 @@ class Literal(ttystatus.Widget):
     def __init__(self, string):
         self.value = string
 
-    def __str__(self):
+    def render(self):
         return self.value
diff --git a/ttystatus/literal_tests.py b/ttystatus/literal_tests.py
index 969439d..73c8964 100644
--- a/ttystatus/literal_tests.py
+++ b/ttystatus/literal_tests.py
@@ -23,4 +23,4 @@ class LiteralTests(unittest.TestCase):
 
     def test_sets_value_correctly(self):
         literal = ttystatus.Literal('foo')
-        self.assertEqual(str(literal), 'foo')
+        self.assertEqual(literal.render(), 'foo')
diff --git a/ttystatus/pathname.py b/ttystatus/pathname.py
index a8b8253..0ecf4a7 100644
--- a/ttystatus/pathname.py
+++ b/ttystatus/pathname.py
@@ -29,7 +29,7 @@ class Pathname(ttystatus.Widget):
         self._key = key
         self.pathname = ''
 
-    def __str__(self):
+    def render(self):
         return self.pathname
         
     def update(self, master):
diff --git a/ttystatus/pathname_tests.py b/ttystatus/pathname_tests.py
index f9e62ef..7f09de0 100644
--- a/ttystatus/pathname_tests.py
+++ b/ttystatus/pathname_tests.py
@@ -25,12 +25,12 @@ class PathnameTests(unittest.TestCase):
         self.w = ttystatus.Pathname('foo')
 
     def test_is_empty_initially(self):
-        self.assertEqual(str(self.w), '')
+        self.assertEqual(self.w.render(), '')
         
     def test_updates(self):
         self.w.update({'foo': 'bar'})
-        self.assertEqual(str(self.w), 'bar')
+        self.assertEqual(self.w.render(), 'bar')
 
     def test_handles_update_to_other_value(self):
         self.w.update({'other': 1})
-        self.assertEqual(str(self.w), '')
+        self.assertEqual(self.w.render(), '')
diff --git a/ttystatus/percent.py b/ttystatus/percent.py
index 840c047..117fecc 100644
--- a/ttystatus/percent.py
+++ b/ttystatus/percent.py
@@ -28,7 +28,7 @@ class PercentDone(ttystatus.Widget):
         self.done = 0
         self.total = 1
         
-    def __str__(self):
+    def render(self):
         try:
             done = float(self.done)
             total = float(self.total)
diff --git a/ttystatus/percent_tests.py b/ttystatus/percent_tests.py
index 5f46498..c7d8d64 100644
--- a/ttystatus/percent_tests.py
+++ b/ttystatus/percent_tests.py
@@ -25,17 +25,17 @@ class PercentDoneTests(unittest.TestCase):
         self.w = ttystatus.PercentDone('done', 'total', decimals=1)
 
     def test_shows_zero_value_initially(self):
-        self.assertEqual(str(self.w), '0.0 %')
+        self.assertEqual(self.w.render(), '0.0 %')
 
     def test_sets_value(self):
         self.w.update({ 'done': 50, 'total': 100 })
-        self.assertEqual(str(self.w), '50.0 %')
+        self.assertEqual(self.w.render(), '50.0 %')
 
     def test_handles_empty_strings_as_values(self):
         self.w.update({ 'done': '', 'total': '' })
-        self.assertEqual(str(self.w), '0.0 %')
+        self.assertEqual(self.w.render(), '0.0 %')
 
     def test_handles_zero_total(self):
         self.w.update({ 'done': 0, 'total': 0 })
-        self.assertEqual(str(self.w), '0.0 %')
+        self.assertEqual(self.w.render(), '0.0 %')
 
diff --git a/ttystatus/progressbar.py b/ttystatus/progressbar.py
index d8189d3..54ca99f 100644
--- a/ttystatus/progressbar.py
+++ b/ttystatus/progressbar.py
@@ -28,7 +28,7 @@ class ProgressBar(ttystatus.Widget):
         self.total = 1
         self.width = width
 
-    def __str__(self):
+    def render(self):
         try:
             done = float(self.done)
             total = float(self.total)
diff --git a/ttystatus/progressbar_tests.py b/ttystatus/progressbar_tests.py
index a229f46..8c7c261 100644
--- a/ttystatus/progressbar_tests.py
+++ b/ttystatus/progressbar_tests.py
@@ -25,37 +25,37 @@ class ProgressBarTests(unittest.TestCase):
         self.w = ttystatus.ProgressBar('done', 'total', 10)
 
     def test_sets_initial_value_to_empty(self):
-        self.assertEqual(str(self.w), '-' * 10)
+        self.assertEqual(self.w.render(), '-' * 10)
 
     def test_shows_zero_percent_for_empty_string_total(self):
         self.w.update({ 'done': 1, 'total': '' })
-        self.assertEqual(str(self.w), '-' * 10)
+        self.assertEqual(self.w.render(), '-' * 10)
 
     def test_shows_zero_percent_for_zero_total(self):
         self.w.update({ 'done': 1, 'total': 0 })
-        self.assertEqual(str(self.w), '-' * 10)
+        self.assertEqual(self.w.render(), '-' * 10)
 
     def test_shows_zero_percent_correctly(self):
         self.w.update({ 'done': 0, 'total': 100 })
-        self.assertEqual(str(self.w), '-' * 10)
+        self.assertEqual(self.w.render(), '-' * 10)
 
     def test_shows_one_percent_correctly(self):
         self.w.update({ 'done': 1, 'total': 100 })
-        self.assertEqual(str(self.w), '-' * 10)
+        self.assertEqual(self.w.render(), '-' * 10)
 
     def test_shows_ten_percent_correctly(self):
         self.w.update({ 'done': 10, 'total': 100 })
-        self.assertEqual(str(self.w), '#' + '-' * 9)
+        self.assertEqual(self.w.render(), '#' + '-' * 9)
 
     def test_shows_ninety_percent_correctly(self):
         self.w.update({ 'done': 90, 'total': 100 })
-        self.assertEqual(str(self.w), '#' * 9 + '-')
+        self.assertEqual(self.w.render(), '#' * 9 + '-')
 
     def test_shows_ninety_ine_percent_correctly(self):
         self.w.update({ 'done': 99, 'total': 100 })
-        self.assertEqual(str(self.w), '#' * 10)
+        self.assertEqual(self.w.render(), '#' * 10)
 
     def test_shows_one_hundred_percent_correctly(self):
         self.w.update({ 'done': 100, 'total': 100 })
-        self.assertEqual(str(self.w), '#' * 10)
+        self.assertEqual(self.w.render(), '#' * 10)
 
diff --git a/ttystatus/remtime.py b/ttystatus/remtime.py
index 9d90895..50529e6 100644
--- a/ttystatus/remtime.py
+++ b/ttystatus/remtime.py
@@ -41,7 +41,7 @@ class RemainingTime(ttystatus.Widget):
         
         return time.time()
         
-    def __str__(self):
+    def render(self):
         if self.started is None:
             self.started = self.get_time()
         duration = self.get_time() - self.started
diff --git a/ttystatus/remtime_tests.py b/ttystatus/remtime_tests.py
index dced388..df6bced 100644
--- a/ttystatus/remtime_tests.py
+++ b/ttystatus/remtime_tests.py
@@ -26,30 +26,30 @@ class RemainingTimeTests(unittest.TestCase):
         self.w.get_time = lambda: 0.0
 
     def test_is_dashes_initially(self):
-        self.assertEqual(str(self.w), '--h--m--s')
+        self.assertEqual(self.w.render(), '--h--m--s')
 
     def test_estimates_and_formats_correctly(self):
-        self.assertEqual(str(self.w), '--h--m--s')
+        self.assertEqual(self.w.render(), '--h--m--s')
         self.w.update({ 'done': 0, 'total': 100 })
         self.w.get_time = lambda: 5.0
         self.w.update({ 'done': 5, 'total': 100 })
-        self.assertEqual(str(self.w), '00h01m35s')
+        self.assertEqual(self.w.render(), '00h01m35s')
         self.w.get_time = lambda: 10.0
         self.w.update({ 'done': 5, 'total': 100 })
-        self.assertEqual(str(self.w), '00h03m10s')
+        self.assertEqual(self.w.render(), '00h03m10s')
         self.w.get_time = lambda: 20.0
         self.w.update({ 'done': 80, 'total': 100 })
-        self.assertEqual(str(self.w), '00h00m05s')
+        self.assertEqual(self.w.render(), '00h00m05s')
 
     def test_handles_zero_speed(self):
         self.w.update({ 'done': 0, 'total': 100 })
         self.w.get_time = lambda: 5.0
         self.w.update({ 'done': 0, 'total': 100 })
-        self.assertEqual(str(self.w), '--h--m--s')
+        self.assertEqual(self.w.render(), '--h--m--s')
 
     def test_handles_empty_strings_for_done_and_total(self):
         self.w.update({ 'done': '', 'total': '' })
         self.w.get_time = lambda: 5.0
         self.w.update({ 'done': '', 'total': '' })
-        self.assertEqual(str(self.w), '--h--m--s')
+        self.assertEqual(self.w.render(), '--h--m--s')
 
diff --git a/ttystatus/status.py b/ttystatus/status.py
index e45c774..526029b 100644
--- a/ttystatus/status.py
+++ b/ttystatus/status.py
@@ -76,7 +76,7 @@ class TerminalStatus(object):
 
     def _render(self):
         '''Format and output all widgets.'''
-        self._m.write(''.join(str(w) for w in self._widgets))
+        self._m.write(''.join(w.render() for w in self._widgets))
     
     def increase(self, key, delta):
         '''Increase value for a key by a given amount.'''
diff --git a/ttystatus/status_tests.py b/ttystatus/status_tests.py
index 03a0499..bb581f6 100644
--- a/ttystatus/status_tests.py
+++ b/ttystatus/status_tests.py
@@ -94,9 +94,9 @@ class TerminalStatusTests(unittest.TestCase):
     def test_updates_widgets_when_value_is_set(self):
         w = ttystatus.String('foo')
         self.ts.add(w)
-        self.assertEqual(str(w), '')
+        self.assertEqual(w.render(), '')
         self.ts['foo'] = 'bar'
-        self.assertEqual(str(w), 'bar')
+        self.assertEqual(w.render(), 'bar')
 
     def test_increases_value(self):
         self.ts['foo'] = 10
@@ -128,5 +128,5 @@ class TerminalStatusTests(unittest.TestCase):
         self.ts.add(w)
         for i in range(n):
             self.ts['value'] = i
-        self.assertEqual(str(w), str(n))
+        self.assertEqual(w.render(), str(n))
 
diff --git a/ttystatus/string.py b/ttystatus/string.py
index a23a8e5..90fb48b 100644
--- a/ttystatus/string.py
+++ b/ttystatus/string.py
@@ -25,7 +25,7 @@ class String(ttystatus.Widget):
         self._key = key
         self.value = ''
 
-    def __str__(self):
+    def render(self):
         return str(self.value)
         
     def update(self, master):
diff --git a/ttystatus/string_tests.py b/ttystatus/string_tests.py
index aad21f5..b377f37 100644
--- a/ttystatus/string_tests.py
+++ b/ttystatus/string_tests.py
@@ -25,12 +25,12 @@ class StringTests(unittest.TestCase):
         self.s = ttystatus.String('foo')
 
     def test_is_empty_initially(self):
-        self.assertEqual(str(self.s), '')
+        self.assertEqual(self.s.render(), '')
         
     def test_updates(self):
         self.s.update({'foo': 'bar'})
-        self.assertEqual(str(self.s), 'bar')
+        self.assertEqual(self.s.render(), 'bar')
         
     def test_handles_non_string_value(self):
         self.s.update({'foo': 123})
-        self.assertEqual(str(self.s), '123')
+        self.assertEqual(self.s.render(), '123')
diff --git a/ttystatus/widget.py b/ttystatus/widget.py
index 17c2df4..9fccc29 100644
--- a/ttystatus/widget.py
+++ b/ttystatus/widget.py
@@ -26,12 +26,15 @@ class Widget(object):
     
     * the widget `update` method is called by TerminalStatus whenever
       any of the values change
-    * the widget `__str__` method is called by TerminalStatus when it is
+    * the widget `render` method is called by TerminalStatus when it is
       time to display things
-    
+
     '''
     
     def __str__(self):
+        raise NotImplementedError()
+    
+    def render(self):
         '''Format the current value.
         
         This will be called only when the value actually needs to be