New List pattern and some bugfixes and tweaks.

code/cpp/echomesh/color/ColorList.pyx

@@ -40,6 +40,13 @@ cdef class ColorList:
             recolumn(self.thisptr, self._columns, cols)
             self._columns = cols
 
+    property size:
+        def __get__(self):
+            return len(self)
+
+        def __set__(self, unsigned int new_size):
+            self.thisptr.resize(new_size)
+
     def append(self, object item):
         cdef FColor c
         if fill_color(item, &c):
@@ -86,8 +93,7 @@ cdef class ColorList:
         original_length = len(self)
         colors = list(colors)
         new_length = len(colors)
-        if return_errors:
-            error_colors = []
+        error_colors = []
 
         self.thisptr.reserve(original_length + new_length)
         for color in colors:
@@ -119,8 +125,9 @@ cdef class ColorList:
 
     def interpolate(self, color_list, float fader, unsigned int smooth=0):
         cdef ColorList cl = toColorList(color_list)
-        cdef ColorList result = ColorList(columns=self.columns)
-        result.thisptr[0] = self.thisptr.interpolate(cl.thisptr[0], fader, smooth)
+        cdef ColorList result = ColorList(columns=self.column or cl.columns)
+        result.thisptr[0] = self.thisptr.interpolate(
+            cl.thisptr[0], fader, smooth)
         return result
 
     def pop(self, int index=-1):

code/cpp/echomesh/color/FColor.h

@@ -134,7 +134,9 @@ class FColor {
     }
 
     struct Comparer {
-        bool operator()(const FColor& x, const FColor& y) { return x.compare(y) < 0; }
+        bool operator()(const FColor& x, const FColor& y) {
+            return x.compare(y) < 0;
+        }
     };
 
     void combine(const FColor& x) {
@@ -149,7 +151,10 @@ class FColor {
     }
 
   private:
-    float red_, green_, blue_, alpha_;
+    float red_ = 0.0;
+    float green_ = 0.0;
+    float blue_ = 0.0;
+    float alpha_ = 1.0;
 };
 
 }  // namespace color

code/cpp/echomesh/color/HSB.h

@@ -62,4 +62,3 @@ class HSB : public ColorModel {
 
 }  // namespace color
 }  // namespace echomesh
-

code/python/echomesh/base/MergeSettings.py

@@ -93,8 +93,6 @@ def save(self):
                 if not os.path.exists(parent):
                     print('Creating directory', parent)
                     os.makedirs(parent)
-                else:
-                    print('Directory exists', parent)
 
                 with open(f, 'wb') as fw:
                     if data:

code/python/echomesh/color/Scroll_test.py

@@ -12,7 +12,7 @@ def setUp(self):
            'plum', 'teal', 'wheat', 'orchid', ])
 
     def doTest(self, dx, dy, expected):
-        result = cechomesh.scroll_color_list(self.data, dx, dy, 4)
+        result = cechomesh.scroll_color_list(self.data, dx, dy, columns=4)
         expected = cechomesh.ColorList(expected)
         self.assertEquals(result, cechomesh.ColorList(expected))
 

code/python/echomesh/pattern/Column.py

@@ -6,7 +6,7 @@
 from echomesh.pattern.Pattern import Pattern
 
 class Column(Pattern):
-    HELP = 'Set or rest the number of columns in an x, y pattern.'
+    HELP = 'Set or reset the number of columns in an x, y pattern.'
 
     SETTINGS = {
       'columns': {

code/python/echomesh/pattern/List.py

@@ -0,0 +1,56 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+from echomesh.Cechomesh import cechomesh
+
+import itertools
+
+from echomesh.pattern.Pattern import Pattern
+from echomesh.util.string.Plural import plural
+
+class List(Pattern):
+    HELP = 'Display a spread of colors between two or more color endpoints.'
+    CONSTANT = True
+    PATTERN_COUNT = 0
+
+    SETTINGS = {
+      'colors': {
+        'default': [],
+        'help': 'A list of colors to be displayed.',
+        },
+      'columns': {
+        'default': 0,
+        'help': 'The number of columns in the result',
+        },
+      }
+
+    PATTERN_COUNT = 0
+
+    def _evaluate(self):
+        colors = self.get_raw('colors')
+        has_lists, has_scalars = False, False
+        for c in colors:
+            is_list = isinstance(c, list)
+            has_lists = has_lists or is_list
+            has_scalars = has_scalars or not is_list
+
+        if has_scalars:
+            if has_lists:
+                raise Exception('Can\'t mix lists and scalars in pattern.List')
+            colors = [colors]
+        max_column = max(len(c) for c in colors)
+        columns = self.get('columns') or max_column
+        if not max_column:
+            # Empty list.
+            return cechomesh.Colorlist(columns=columns)
+
+        ce = (cechomesh.color_list_with_errors(c) for c in colors)
+        color_lists, errors = zip(*ce)
+        errors = list(itertools.chain(*errors))
+        if errors:
+            raise Exception('\nCan\'t understand %s: %s.' % (
+                plural(len(errors), 'color'), ', '.join(errors)))
+        result = cechomesh.ColorList(columns=columns)
+        for i, cl in enumerate(color_lists):
+            cl.size = columns
+            result.extend(cl)
+        return result

code/python/echomesh/pattern/Registry.py

@@ -11,6 +11,7 @@
   'Image',
   'Inject',
   'Insert',
+  'List',
   'Mirror',
   'Scroll',
   'Spread',