Move columnization code out of GUI code so we can test it better.

IPython/frontend/qt/console/console_widget.py

@@ -19,6 +19,7 b' from IPython.external.qt import QtCore, QtGui'
 from IPython.config.configurable import Configurable
 from IPython.frontend.qt.rich_text import HtmlExporter
 from IPython.frontend.qt.util import MetaQObjectHasTraits, get_font
+from IPython.utils.text import columnize
 from IPython.utils.traitlets import Bool, Enum, Int, Unicode
 from ansi_code_processor import QtAnsiCodeProcessor
 from completion_widget import CompletionWidget
@@ -1295,52 +1296,7 b' class ConsoleWidget(Configurable, QtGui.QWidget):'
         width = self._control.viewport().width()
         char_width = QtGui.QFontMetrics(self.font).width(' ')
         displaywidth = max(10, (width / char_width) - 1)
-
-        # Some degenerate cases.
-        size = len(items)
-        if size == 0: 
-            return '\n'
-        elif size == 1:
-            return '%s\n' % items[0]
-
-        # Try every row count from 1 upwards
-        array_index = lambda nrows, row, col: nrows*col + row
-        for nrows in range(1, size):
-            ncols = (size + nrows - 1) // nrows
-            colwidths = []
-            totwidth = -len(separator)
-            for col in range(ncols):
-                # Get max column width for this column
-                colwidth = 0
-                for row in range(nrows):
-                    i = array_index(nrows, row, col)
-                    if i >= size: break
-                    x = items[i]
-                    colwidth = max(colwidth, len(x))
-                colwidths.append(colwidth)
-                totwidth += colwidth + len(separator)
-                if totwidth > displaywidth: 
-                    break
-            if totwidth <= displaywidth: 
-                break
-
-        # The smallest number of rows computed and the max widths for each
-        # column has been obtained. Now we just have to format each of the rows.
-        string = ''
-        for row in range(nrows):
-            texts = []
-            for col in range(ncols):
-                i = row + nrows*col
-                if i >= size:
-                    texts.append('')
-                else:
-                    texts.append(items[i])
-            while texts and not texts[-1]:
-                del texts[-1]
-            for col in range(len(texts)):
-                texts[col] = texts[col].ljust(colwidths[col])
-            string += '%s\n' % separator.join(texts)
-        return string
+        return columnize(items, separator, displaywidth)
 
     def _get_block_plain_text(self, block):
         """ Given a QTextBlock, return its unformatted text.

IPython/utils/text.py

@@ -611,3 +611,69 b' class EvalFormatter(Formatter):'
                 raise KeyError(key)
 
 
+def columnize(items, separator='  ', displaywidth=80):
+    """ Transform a list of strings into a single string with columns.
+
+    Parameters
+    ----------
+    items : sequence of strings
+        The strings to process.
+
+    separator : str, optional [default is two spaces]
+        The string that separates columns.
+
+    displaywidth : int, optional [default is 80]
+        Width of the display in number of characters.
+    
+    Returns
+    -------
+    The formatted string.
+    """
+    # Note: this code is adapted from columnize 0.3.2.
+    # See http://code.google.com/p/pycolumnize/
+
+    # Some degenerate cases.
+    size = len(items)
+    if size == 0: 
+        return '\n'
+    elif size == 1:
+        return '%s\n' % items[0]
+
+    # Try every row count from 1 upwards
+    array_index = lambda nrows, row, col: nrows*col + row
+    for nrows in range(1, size):
+        ncols = (size + nrows - 1) // nrows
+        colwidths = []
+        totwidth = -len(separator)
+        for col in range(ncols):
+            # Get max column width for this column
+            colwidth = 0
+            for row in range(nrows):
+                i = array_index(nrows, row, col)
+                if i >= size: break
+                x = items[i]
+                colwidth = max(colwidth, len(x))
+            colwidths.append(colwidth)
+            totwidth += colwidth + len(separator)
+            if totwidth > displaywidth: 
+                break
+        if totwidth <= displaywidth: 
+            break
+
+    # The smallest number of rows computed and the max widths for each
+    # column has been obtained. Now we just have to format each of the rows.
+    string = ''
+    for row in range(nrows):
+        texts = []
+        for col in range(ncols):
+            i = row + nrows*col
+            if i >= size:
+                texts.append('')
+            else:
+                texts.append(items[i])
+        while texts and not texts[-1]:
+            del texts[-1]
+        for col in range(len(texts)):
+            texts[col] = texts[col].ljust(colwidths[col])
+        string += '%s\n' % separator.join(texts)
+    return string