Adding iteration to ProgressBar to make it a more useful utility

IPython/core/display.py

@@ -774,6 +774,19 b' class ProgressBar(DisplayObject):'
         self._progress = value
         self.update()
 
+    def __iter__(self):
+        self.display()
+        self._progress = -1 # First iteration is 0
+        return self
+
+    def __next__(self):
+        """Returns current value and increments display by one."""
+        self.progress += 1
+        if self.progress < self.total:
+            return self.progress
+        else:
+            raise StopIteration()
+
 class JSON(DisplayObject):
     """JSON expects a JSON-able dict or list
 

IPython/core/tests/test_display.py

@@ -196,11 +196,18 b' def test_displayobject_repr():'
 
 def test_progress():
     p = display.ProgressBar(10)
-    nt.assert_true('0/10' in repr(p))
+    nt.assert_in('0/10',repr(p))
     p.html_width = '100%'
     p.progress = 5
     nt.assert_equal(p._repr_html_(), "<progress style='width:100%' max='10' value='5'></progress>")
 
+def test_progress_iter(capsys):
+    for i in display.ProgressBar(5):
+        out, err = capsys.readouterr()
+        nt.assert_in('{0}/5'.format(i), out)
+    out, err = capsys.readouterr()
+    nt.assert_in('5/5', out)
+
 def test_json():
     d = {'a': 5}
     lis = [d]

examples/IPython Kernel/Updating Displays.ipynb

@@ -21,10 +21,8 b''
   },
   {
    "cell_type": "code",
-   "execution_count": 10,
-   "metadata": {
-    "collapsed": true
-   },
+   "execution_count": 1,
+   "metadata": {},
    "outputs": [],
    "source": [
     "from IPython.display import display, update_display"
@@ -32,7 +30,7 b''
   },
   {
    "cell_type": "code",
-   "execution_count": 13,
+   "execution_count": 2,
    "metadata": {},
    "outputs": [
     {
@@ -50,7 +48,7 b''
        "<DisplayHandle display_id=update-me>"
       ]
      },
-     "execution_count": 13,
+     "execution_count": 2,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -70,7 +68,7 b''
   },
   {
    "cell_type": "code",
-   "execution_count": 14,
+   "execution_count": 3,
    "metadata": {},
    "outputs": [
     {
@@ -97,10 +95,8 b''
   },
   {
    "cell_type": "code",
-   "execution_count": 15,
-   "metadata": {
-    "collapsed": true
-   },
+   "execution_count": 4,
+   "metadata": {},
    "outputs": [],
    "source": [
     "handle.update('z')"
@@ -116,7 +112,7 b''
   },
   {
    "cell_type": "code",
-   "execution_count": 16,
+   "execution_count": 5,
    "metadata": {},
    "outputs": [
     {
@@ -131,10 +127,10 b''
     {
      "data": {
       "text/plain": [
-       "<DisplayHandle display_id=07fc47b2ef652ccb70addeee3eb0981a>"
+       "<DisplayHandle display_id=118a56127f42348f8893440da7181c57>"
       ]
      },
-     "execution_count": 16,
+     "execution_count": 5,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -154,7 +150,7 b''
   },
   {
    "cell_type": "code",
-   "execution_count": 17,
+   "execution_count": 6,
    "metadata": {},
    "outputs": [
     {
@@ -173,7 +169,7 b''
   },
   {
    "cell_type": "code",
-   "execution_count": 18,
+   "execution_count": 7,
    "metadata": {},
    "outputs": [
     {
@@ -200,10 +196,8 b''
   },
   {
    "cell_type": "code",
-   "execution_count": 19,
-   "metadata": {
-    "collapsed": true
-   },
+   "execution_count": 8,
+   "metadata": {},
    "outputs": [],
    "source": [
     "update_display('z', display_id='here')"
@@ -222,16 +216,16 b''
   },
   {
    "cell_type": "code",
-   "execution_count": 14,
+   "execution_count": 9,
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/html": [
-       "<progress style='width:100%' max='10' value='10'></progress>"
+       "<progress style='width:60ex' max='10' value='10'></progress>"
       ],
       "text/plain": [
-       "<IPython.core.display.ProgressBar object>"
+       "[============================================================] 10/10"
       ]
      },
      "metadata": {},
@@ -254,16 +248,16 b''
   },
   {
    "cell_type": "code",
-   "execution_count": 15,
+   "execution_count": 10,
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/html": [
-       "<progress style='width:100%' max='10' value='10'></progress>"
+       "<progress style='width:60ex' max='10' value='10'></progress>"
       ],
       "text/plain": [
-       "<IPython.core.display.ProgressBar object>"
+       "[============================================================] 10/10"
       ]
      },
      "metadata": {},
@@ -285,6 +279,36 b''
    "cell_type": "markdown",
    "metadata": {},
    "source": [
+    "The ProgressBar also has an update built into iteration:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<progress style='width:60ex' max='10' value='10'></progress>"
+      ],
+      "text/plain": [
+       "[============================================================] 10/10"
+      ]
+     },
+     "metadata": {},
+     "output_type": "display_data"
+    }
+   ],
+   "source": [
+    "for i in ProgressBar(10):\n",
+    "    time.sleep(0.25)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
     "We would encourage any updatable-display objects that track their own display_ids to follow-suit with `.display()` and `.update()` or `.update_display()` methods."
    ]
   }