Remove usage of Trait() (#925)

* Replace Trait() by Union() where appropriate.

* Replace Trait() usage where it is simply applying a default.

* Replace uses of Trait() by Enum() or Map() where appropriate.

* Replace Trait() by custom TraitTypes where appropriate.

* Remove some stray Trait() imports.

* Add tests for scroll bar traits; other fixes from review.

enable/abstract_window.py

@@ -14,7 +14,7 @@
 
 # Enthought library imports
 from traits.api import (
-    Any, Bool, Event, Float, HasTraits, Instance, List, Property, Trait, Tuple,
+    Any, Bool, Event, Float, HasTraits, Instance, List, Property, Tuple, Union,
 )
 
 
@@ -54,7 +54,7 @@ class AbstractWindow(HasTraits):
 
     # When a component captures the mouse, it can optionally store a
     # dispatch order for events (until it releases the mouse).
-    mouse_owner_dispatch_history = Trait(None, None, List, transient=True)
+    mouse_owner_dispatch_history = Union(None, List, transient=True)
 
     # A scaling constant applied to any GraphicsContext used for drawing the
     # window's component.
@@ -89,7 +89,7 @@ class AbstractWindow(HasTraits):
     _prev_event_handler = Instance(Component, transient=True)
 
     # (dx, dy) integer size of the Window.
-    _size = Trait(None, Tuple, transient=True)
+    _size = Union(None, Tuple, transient=True)
 
     # The regions to update upon redraw
     _update_region = Any(transient=True)

enable/canvas.py

@@ -10,7 +10,7 @@
 """ Defines the enable Canvas class """
 
 # Enthought library imports
-from traits.api import Bool, List, Trait, Tuple
+from traits.api import Bool, List, Tuple, Union
 from kiva.api import FILL
 
 
@@ -39,7 +39,7 @@ class Canvas(Container):
     # of the "region of interest" that it should use when computing its
     # notional bounds for clipping and event handling purposes.  If this trait
     # is None, then the canvas really does behave as if it has no bounds.
-    view_bounds = Trait(None, None, Tuple)
+    view_bounds = Union(None, Tuple)
 
     # The (x,y) position of the lower-left corner of the rectangle
     # corresponding to the dimensions in self.bounds.  Unlike self.position,

enable/component.py

@@ -13,7 +13,7 @@
 
 # Enthought library imports
 from traits.api import (
-    Any, Bool, Delegate, Enum, Float, Instance, Int, List, Property, Str, Trait
+    Any, Bool, Delegate, Enum, Float, Instance, Int, List, Property, Str, Union
 )
 from kiva.api import FILL, STROKE
 
@@ -93,7 +93,7 @@ class Component(CoordinateBox, Interactor):
     # The ratio of the component's width to its height.  This is used by
     # the component itself to maintain bounds when the bounds are changed
     # independently, and is also used by the layout system.
-    aspect_ratio = Trait(None, None, Float)
+    aspect_ratio = Union(None, Float)
 
     # When the component's bounds are set to a (width,height) tuple that does
     # not conform to the set aspect ratio, does the component center itself
@@ -113,7 +113,7 @@ class Component(CoordinateBox, Interactor):
     # component specifies, say, a fixed preferred width of 50 and another one
     # specifies a fixed preferred width of 100, then the latter component will
     # always be twice as wide as the former.
-    fixed_preferred_size = Trait(None, None, bounds_trait)
+    fixed_preferred_size = Union(None, bounds_trait)
 
     # ------------------------------------------------------------------------
     # Overlays and underlays

enable/drawing/drag_box.py

@@ -18,7 +18,7 @@
 # Enthought library imports
 from enable.primitives.api import Box
 from enable.enable_traits import Pointer
-from traits.api import Event, Float, Trait, Tuple
+from traits.api import Event, Float, Tuple, Union
 
 # Application specific imports.
 
@@ -43,8 +43,8 @@ class DragBox(Box):
     complete = Event
 
     # Constraints on size:
-    x_bounds = Trait(None, None, Tuple(Float, Float))
-    y_bounds = Trait(None, None, Tuple(Float, Float))
+    x_bounds = Union(None, Tuple(Float, Float))
+    y_bounds = Union(None, Tuple(Float, Float))
 
     # Pointers. ####
 

enable/enable_traits.py

@@ -16,7 +16,9 @@
 
 # Enthought library imports
 from kiva.trait_defs.api import KivaFont
-from traits.api import List, PrefixList, PrefixMap, Range, Trait, TraitFactory
+from traits.api import (
+    BaseFloat, List, Map, PrefixList, PrefixMap, Range, TraitType, Union,
+)
 from traitsui.api import ImageEnumEditor, EnumEditor
 
 # Try to get the CList trait; for traits 2 backwards compatibility, fall back
@@ -100,26 +102,23 @@
 # -----------------------------------------------------------------------------
 
 # Privates used for specification of line style trait.
-__line_style_trait_values = {
+_line_style_trait_values = {
     "solid": None,
     "dot dash": array([3.0, 5.0, 9.0, 5.0]),
     "dash": array([6.0, 6.0]),
     "dot": array([2.0, 2.0]),
     "long dash": array([9.0, 5.0]),
 }
-__line_style_trait_map_keys = list(__line_style_trait_values.keys())
-LineStyleEditor = EnumEditor(values=__line_style_trait_map_keys)
-
-
-def __line_style_trait(value="solid", **metadata):
-    return Trait(
-        value, __line_style_trait_values, editor=LineStyleEditor, **metadata
-    )
 
+# An editor preset for line styles.
+LineStyleEditor = EnumEditor(values=list(_line_style_trait_values))
 
 # A mapped trait for use in specification of line style attributes.
-LineStyle = TraitFactory(__line_style_trait)
-
+LineStyle = Map(
+    _line_style_trait_values,
+    default_value='solid',
+    editor=LineStyleEditor,
+)
 
 # -----------------------------------------------------------------------------
 #  Trait definitions:
@@ -132,9 +131,6 @@ def __line_style_trait(value="solid", **metadata):
 bounds_trait = CList([0.0, 0.0])  # (w,h)
 coordinate_trait = CList([0.0, 0.0])  # (x,y)
 
-# bounds_trait = Trait((0.0, 0.0, 20.0, 20.0), valid_bounds,
-#                      editor=bounds_editor)
-
 # Component minimum size trait
 # PZW: Make these just floats, or maybe remove them altogether.
 ComponentMinSize = Range(0.0, 99999.0)
@@ -152,8 +148,55 @@ def __line_style_trait(value="solid", **metadata):
 border_size_trait = Range(0, 8, editor=border_size_editor)
 
 # Time interval trait:
-TimeInterval = Trait(None, None, Range(0.0, 3600.0))
+TimeInterval = Union(None, Range(0.0, 3600.0))
 
 # Stretch traits:
 Stretch = Range(0.0, 1.0, value=1.0)
 NoStretch = Stretch(0.0)
+
+
+# Scrollbar traits
+class ScrollBarRange(TraitType):
+    """ Trait that holds a (low, high, page_size, line_size) range tuple.
+    """
+
+    def validate(self, object, name, value):
+        if isinstance(value, (tuple, list)) and (len(value) == 4):
+            low, high, page_size, line_size = value
+            try:
+                if high < low:
+                    low, high = high, low
+                elif high == low:
+                    high = low + 1.0
+                page_size = max(min(page_size, high - low), 0.0)
+                line_size = max(min(line_size, page_size), 0.0)
+                return (
+                    float(low),
+                    float(high),
+                    float(page_size),
+                    float(line_size),
+                )
+            except Exception:
+                self.error(object, name, value)
+
+        self.error(object, name, value)
+
+    def info(self):
+        return "a (low, high, page_size, line_size) range tuple"
+
+
+class ScrollPosition(BaseFloat):
+    """A Trait that ensures the position is within the scroll range.
+    """
+
+    #: the name of the trait holding the range information.
+    range_name = "range"
+
+    def validate(self, object, name, value):
+        value = super().validate(object, name, value)
+        try:
+            low, high, page_size, line_size = getattr(object, self.range_name)
+            x = max(min(float(value), high - page_size), low)
+            return x
+        except Exception:
+            self.error(object, name, value)

enable/interactor.py

@@ -11,7 +11,7 @@
 
 # Enthought library imports
 from kiva.api import affine_identity
-from traits.api import Any, Bool, HasTraits, List, Property, Str, Trait
+from traits.api import Any, Bool, HasTraits, List, Property, Str, Union
 
 # Local relative imports
 from enable.colors import ColorTrait
@@ -62,7 +62,7 @@ class Interactor(HasTraits):
     pointer = Pointer
 
     # The "tooltip" to display if a user mouse-overs this interactor
-    tooltip = Trait(None, None, Str)
+    tooltip = Union(None, Str)
 
     # The cursor "style" to use
     cursor_style = cursor_style_trait

enable/markers.py

@@ -15,7 +15,7 @@
 from numpy import array, pi
 
 # Enthought library imports
-from traits.api import HasTraits, Bool, Instance, Trait
+from traits.api import HasTraits, Bool, Instance, Map
 from traitsui.api import EnumEditor
 from kiva.api import (
     CIRCLE_MARKER, CROSS_MARKER, DIAMOND_MARKER, DOT_MARKER, FILL_STROKE,
@@ -470,8 +470,6 @@ def get_compiled_path(self, size):
 }
 
 #: A mapped trait that allows string naming of marker classes.
-MarkerTrait = Trait(
-    "square", MarkerNameDict, editor=EnumEditor(values=marker_names)
-)
+MarkerTrait = Map(MarkerNameDict, default_value="square")
 
 marker_trait = MarkerTrait

enable/primitives/line.py

@@ -13,7 +13,7 @@
 
 # Enthought library imports.
 from kiva.api import FILL, FILL_STROKE, STROKE
-from traits.api import Any, Event, Float, List, Trait, Bool
+from traits.api import Any, Event, Float, List, Bool
 
 # Local imports.
 from enable.api import border_size_trait, Component
@@ -36,7 +36,7 @@ class Line(Component):
     line_dash = Any
 
     # The width of the line.
-    line_width = Trait(1, border_size_trait)
+    line_width = border_size_trait(1)
 
     # The points that make up this polygon.
     points = List  # List of Tuples

enable/primitives/polygon.py

@@ -6,7 +6,7 @@
 # Enthought library imports.
 from kiva.api import EOF_FILL_STROKE, FILL, FILL_STROKE, points_in_polygon
 from traits.api import (
-    Any, Event, Float, HasTraits, Instance, List, Property, Trait, Tuple
+    Any, Event, Float, HasTraits, Instance, List, Map, Property, Tuple
 )
 from traitsui.api import Group, View
 
@@ -42,14 +42,15 @@ class Polygon(Component):
     border_dash = Any
 
     # The thickness of the border of this polygon.
-    border_size = Trait(1, border_size_trait)
+    border_size = border_size_trait(1)
 
     # Event fired when the polygon is "complete".
     complete = Event
 
     # The rule to use to determine the inside of the polygon.
-    inside_rule = Trait(
-        "winding", {"winding": FILL_STROKE, "oddeven": EOF_FILL_STROKE}
+    inside_rule = Map(
+        {"winding": FILL_STROKE, "oddeven": EOF_FILL_STROKE},
+        default_value="winding",
     )
 
     # The points that make up this polygon.

enable/qt4/scrollbar.py

@@ -13,47 +13,10 @@
 """
 
 from pyface.qt import QtCore, QtGui
-from traits.api import Any, Bool, Enum, Float, Int, Property, Trait, TraitError
+from traits.api import Any, Bool, Enum, Float, Int, Property
 
 from enable.component import Component
-
-
-def valid_range(object, name, value):
-    """ Verify that a set of range values for a scrollbar is valid.
-    """
-    try:
-        if (type(value) in (tuple, list)) and (len(value) == 4):
-            low, high, page_size, line_size = value
-            if high < low:
-                low, high = high, low
-            elif high == low:
-                high = low + 1.0
-            page_size = max(min(page_size, high - low), 0.0)
-            line_size = max(min(line_size, page_size), 0.0)
-            return (
-                float(low),
-                float(high),
-                float(page_size),
-                float(line_size),
-            )
-    except Exception:
-        raise
-    raise TraitError
-
-
-valid_range.info = "a (low,high,page_size,line_size) range tuple"
-
-
-def valid_scroll_position(object, name, value):
-    """ Verify that a specified scroll bar position is valid.
-    """
-    try:
-        low, high, page_size, line_size = object.range
-        x = max(min(float(value), high - page_size), low)
-        return x
-    except Exception:
-        raise
-    raise TraitError
+from enable.enable_traits import ScrollBarRange, ScrollPosition
 
 
 class QResizableScrollBar(QtGui.QScrollBar):
@@ -74,17 +37,17 @@ class NativeScrollBar(Component):
 
     # The current position of the scroll bar.  This must be within the range
     # (self.low, self.high)
-    scroll_position = Trait(0.0, valid_scroll_position)
+    scroll_position = ScrollPosition()
 
     # A tuple (low, high, page_size, line_size).  Can be accessed using
     # convenience properties (see below).
-    range = Trait((0.0, 100.0, 10.0, 1.0), valid_range)
+    range = ScrollBarRange((0.0, 100.0, 10.0, 1.0))
 
     # The orientation of the scrollbar
-    orientation = Trait("horizontal", "vertical")
+    orientation = Enum("horizontal", "vertical")
 
     # Is y=0 at the top or bottom?
-    origin = Trait("bottom", "top")
+    origin = Enum("bottom", "top")
 
     # Determines if the scroll bar should be visible and respond to events
     enabled = Bool(True)

enable/slider.py

@@ -12,7 +12,7 @@
 # Enthought library imports
 from kiva.api import STROKE
 from traits.api import (
-    Any, Bool, Enum, Float, Int, Property, Trait, observe,
+    Any, Bool, Enum, Float, Int, Map, Property, observe,
 )
 from traitsui.api import EnumEditor
 
@@ -21,13 +21,9 @@
 from .component import Component
 from .markers import CustomMarker, MarkerNameDict, marker_names
 
-slider_marker_names = list(marker_names) + ["rect"]
-SliderMarkerTrait = Trait(
-    "rect",
-    "rect",
-    MarkerNameDict,
-    editor=EnumEditor(values=slider_marker_names),
-)
+slider_marker_map = {'rect': None}
+slider_marker_map.update(MarkerNameDict)
+SliderMarkerTrait = Map(slider_marker_map, default_value='rect')
 
 
 class Slider(Component):