diff --git a/progress/__init__.py b/progress/__init__.py
index 515b31f..b4d16dc 100644
--- a/progress/__init__.py
+++ b/progress/__init__.py
@@ -14,6 +14,7 @@
 
 from __future__ import division
 
+from datetime import timedelta
 from math import ceil
 from sys import stderr
 from time import time
@@ -26,16 +27,25 @@ class Infinite(object):
     file = stderr
 
     def __init__(self, *args, **kwargs):
-        self.ctx = {}
-        for key, val in kwargs.items():
-            if hasattr(self, key):
-                setattr(self, key, val)
-            else:
-                self.ctx[key] = val
-
-        self.index = 0
         self.avg = 0
-        self._ts = time()
+        self.index = 0
+        self.start_ts = time()
+        self._ts = self.start_ts
+        for key, val in kwargs.items():
+            setattr(self, key, val)
+
+    def __getitem__(self, key):
+        if key.startswith('_'):
+            return None
+        return getattr(self, key, None)
+
+    @property
+    def elapsed(self):
+        return int(time() - self.start_ts)
+
+    @property
+    def elapsed_td(self):
+        return timedelta(seconds=self.elapsed)
 
     def update_stats(self):
         # Calculate moving average
@@ -44,10 +54,6 @@ class Infinite(object):
         self.avg = (dt + self.index * self.avg) / (self.index + 1) if self.avg else dt
         self._ts = now
 
-        kv = [(key, val) for key, val in self.__dict__.items()
-                         if not key.startswith('_')]
-        self.ctx.update(kv)
-
     def update(self):
         pass
 
@@ -75,8 +81,15 @@ class Progress(Infinite):
     def __init__(self, *args, **kwargs):
         super(Progress, self).__init__(*args, **kwargs)
         self.max = kwargs.get('max', 100)
-        self.eta = 0
-        self.elapsed = 0
+        self.remaining = self.max
+
+    @property
+    def eta(self):
+        return int(ceil(self.avg * self.remaining))
+
+    @property
+    def eta_td(self):
+        return timedelta(seconds=self.eta)
 
     def update_stats(self):
         self.progress = min(1, self.index / self.max)
@@ -88,14 +101,8 @@ class Progress(Infinite):
         if self.delta:
             dt = (now - self._ts) / self.delta
             self.avg = (dt + self.index * self.avg) / (self.index + 1) if self.avg else dt
-            self.eta = int(ceil(self.avg * self.remaining))
-            self.elapsed += now - self._ts
         self._ts = now
 
-        kv = [(key, val) for key, val in self.__dict__.items()
-                         if not key.startswith('_')]
-        self.ctx.update(kv)
-
     def start(self):
         self.delta = 0
         self.update_stats()
diff --git a/progress/bar.py b/progress/bar.py
index 311b47a..8ce1461 100644
--- a/progress/bar.py
+++ b/progress/bar.py
@@ -32,10 +32,10 @@ class Bar(WritelnMixin, Progress):
         filled_length = int(self.width * self.progress)
         empty_length = self.width - filled_length
 
-        message = self.message % self.ctx
+        message = self.message % self
         bar = self.fill * filled_length
         empty = self.empty_fill * empty_length
-        suffix = self.suffix % self.ctx
+        suffix = self.suffix % self
         line = ''.join([message, self.bar_prefix, bar, empty, self.bar_suffix,
                         suffix])
         self.writeln(line)
@@ -69,11 +69,11 @@ class IncrementalBar(Bar):
         empty_length = self.width - filled_length
         phase = expanded_length - (filled_length * nphases)
 
-        message = self.message % self.ctx
+        message = self.message % self
         bar = self.phases[-1] * filled_length
         current = self.phases[phase] if phase > 0 else ''
         empty = self.empty_fill * max(0, empty_length - len(current))
-        suffix = self.suffix % self.ctx
+        suffix = self.suffix % self
         line = ''.join([message, self.bar_prefix, bar, current, empty,
                         self.bar_suffix, suffix])
         self.writeln(line)
diff --git a/test_progress.py b/test_progress.py
index e87b670..f70c6a3 100755
--- a/test_progress.py
+++ b/test_progress.py
@@ -10,13 +10,16 @@ from progress.bar import (Bar, ChargingBar, FillingSquaresBar,
 from progress.spinner import Spinner, PieSpinner, MoonSpinner, LineSpinner
 from progress.counter import Counter, Countdown, Stack, Pie
 
-
-for bar in (Bar, ChargingBar, FillingSquaresBar, FillingCirclesBar):
-    for i in bar(bar.__name__).iter(range(100)):
+for bar_cls in (Bar, ChargingBar, FillingSquaresBar, FillingCirclesBar):
+    suffix = '%(index)d/%(max)d [%(elapsed)d / %(eta)d]'
+    bar = bar_cls(bar_cls.__name__, suffix=suffix)
+    for i in bar.iter(range(100)):
         sleep(0.04)
 
-for bar in (IncrementalBar, ShadyBar):
-    for i in bar(bar.__name__).iter(range(200)):
+for bar_cls in (IncrementalBar, ShadyBar):
+    suffix = '%(percent)d%% [%(elapsed_td)s / %(eta_td)s]'
+    bar = bar_cls(bar_cls.__name__, suffix=suffix)
+    for i in bar.iter(range(200)):
         sleep(0.02)
 
 for spin in (Spinner, PieSpinner, MoonSpinner, LineSpinner):
@@ -26,7 +29,7 @@ for spin in (Spinner, PieSpinner, MoonSpinner, LineSpinner):
 
 for singleton in (Counter, Countdown, Stack, Pie):
     for i in singleton(singleton.__name__ + ' ').iter(range(100)):
-        sleep(0.04)
+        sleep(0.03)
     print()
 
 bar = IncrementalBar('Random', backtrack=True, suffix='')