Simplify/fix some manual manipulation of len(args).

anntzer · anntzer · commit 5e8cf998f604 · 2018-04-06T00:20:02.000-07:00
The note removed in contributing.rst is simply not true anymore in Py3.

The changes in patches.py fix what appears to have been a bug (well, I'd
rather we decide once and for all whether we want to accept `(x, y)` or
`((x, y))` but until then we may as well make sure both work -- end of
rant).
diff --git a/doc/devel/contributing.rst b/doc/devel/contributing.rst
@@ -410,26 +410,6 @@ local arguments and the rest are passed on as
           self.add_line(line)
           lines.append(line)
 
-Note: there is a use case when ``kwargs`` are meant to be used locally
-in the function (not passed on), but you still need the ``**kwargs``
-idiom.  That is when you want to use ``*args`` to allow variable
-numbers of non-keyword args.  In this case, python will not allow you
-to use named keyword args after the ``*args`` usage, so you will be
-forced to use ``**kwargs``.  An example is
-:meth:`matplotlib.contour.ContourLabeler.clabel`::
-
-  # in contour.py
-  def clabel(self, *args, **kwargs):
-      fontsize = kwargs.get('fontsize', None)
-      inline = kwargs.get('inline', 1)
-      self.fmt = kwargs.get('fmt', '%1.3f')
-      colors = kwargs.get('colors', None)
-      if len(args) == 0:
-          levels = self.levels
-          indices = range(len(self.levels))
-      elif len(args) == 1:
-         ...etc...
-
 .. _using_logging:
 
 Using logging for debug messages
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -156,6 +156,7 @@ def __setstate__(self, state):
         self.set_prop_cycle()
 
     def set_prop_cycle(self, *args, **kwargs):
+        # Can't do `args == (None,)` as that crashes cycler.
         if not (args or kwargs) or (len(args) == 1 and args[0] is None):
             prop_cycler = rcParams['axes.prop_cycle']
         else:
@@ -1206,6 +1207,7 @@ def set_prop_cycle(self, *args, **kwargs):
         if args and kwargs:
             raise TypeError("Cannot supply both positional and keyword "
                             "arguments to this method.")
+        # Can't do `args == (None,)` as that crashes cycler.
         if len(args) == 1 and args[0] is None:
             prop_cycle = None
         else:
diff --git a/lib/matplotlib/patches.py b/lib/matplotlib/patches.py
@@ -775,7 +775,7 @@ def set_bounds(self, *args):
 
         ACCEPTS: (left, bottom, width, height)
         """
-        if len(args) == 0:
+        if len(args) == 1:
             l, b, w, h = args[0]
         else:
             l, b, w, h = args
@@ -2628,7 +2628,7 @@ def set_bounds(self, *args):
 
         ACCEPTS: (left, bottom, width, height)
         """
-        if len(args) == 0:
+        if len(args) == 1:
             l, b, w, h = args[0]
         else:
             l, b, w, h = args
diff --git a/lib/matplotlib/tri/triplot.py b/lib/matplotlib/tri/triplot.py
@@ -41,9 +41,7 @@ def triplot(ax, *args, **kwargs):
     x, y, edges = (tri.x, tri.y, tri.edges)
 
     # Decode plot format string, e.g., 'ro-'
-    fmt = ""
-    if len(args) > 0:
-        fmt = args[0]
+    fmt = args[0] if args else ""
     linestyle, marker, color = matplotlib.axes._base._process_plot_format(fmt)
 
     # Insert plot format string into a copy of kwargs (kwargs values prevail).
