Merge pull request #230 from enthought/sync-enaml-with-chaco

Sync enaml with chaco

enaml/runner.py

@@ -9,23 +9,72 @@
 import os
 import sys
 import types
+import warnings
 
 from enaml import imports
 from enaml.stdlib.sessions import show_simple_view
 from enaml.core.parser import parse
 from enaml.core.enaml_compiler import EnamlCompiler
 
 
+def prepare_toolkit(toolkit_option):
+    """ Prepare the toolkit to be used by Enaml.
+
+    This function determines the Enaml toolkit based on the values of
+    the toolkit option and the ETS_TOOLKIT environment variable. ETS
+    gui components default to Wx when ETS_TOOLKIT is not defined, but
+    Enaml defaults to Qt. Under this condition, ETS_TOOLKIT is updated
+    to be consistent with Enaml. If ETS_TOOLKIT is already set and it
+    is incompatibile with the -t option, a warning is raised.
+
+    Parameters
+    ----------
+    toolkit_option : str
+        The toolkit option provided to the enaml-run script.
+
+    Returns
+    -------
+    result : str
+       The toolkit to be used by enaml.
+
+    """
+    if 'ETS_TOOLKIT' in os.environ:
+        ets_toolkit = os.environ['ETS_TOOLKIT'].lower().split('.')[0][:2]
+        if toolkit_option == 'default' and ets_toolkit in ('wx', 'qt'):
+            enaml_toolkit = ets_toolkit
+        else:
+            enaml_toolkit = 'wx' if toolkit_option == 'wx' else 'qt'
+            if ets_toolkit != enaml_toolkit:
+                msg = (
+                    'The --toolkit option is different from the ETS_TOOLKIT '
+                    'environment variable, which can cause incompatibility '
+                    'issues when using enable or chaco components.'
+                )
+                warnings.warn(msg)
+    else:
+        if toolkit_option == 'wx':
+            enaml_toolkit = 'wx'
+            os.environ['ETS_TOOLKIT'] = 'wx'
+        else:
+            enaml_toolkit = 'qt'
+            os.environ['ETS_TOOLKIT'] = 'qt4'
+    return enaml_toolkit
+
+
 def main():
     usage = 'usage: %prog [options] enaml_file [script arguments]'
     parser = optparse.OptionParser(usage=usage, description=__doc__)
     parser.allow_interspersed_args = False
-    parser.add_option('-c', '--component', default='Main',
-                      help='The component to view')
-    parser.add_option('-t', '--toolkit', default='qt',
-                      help='The GUI toolikit to use')
+    parser.add_option(
+        '-c', '--component', default='Main', help='The component to view'
+    )
+    parser.add_option(
+        '-t', '--toolkit', default='default',
+        help='The GUI toolkit to use [default: qt or ETS_TOOLKIT].'
+    )
 
     options, args = parser.parse_args()
+    toolkit = prepare_toolkit(options.toolkit)
 
     if len(args) == 0:
         print 'No .enaml file specified'
@@ -47,8 +96,8 @@ def main():
     module.__file__ = enaml_file
     ns = module.__dict__
 
-    # Put the directory of the Enaml file first in the path so relative imports
-    # can work.
+    # Put the directory of the Enaml file first in the path so relative
+    # imports can work.
     sys.path.insert(0, os.path.abspath(os.path.dirname(enaml_file)))
     # Bung in the command line arguments.
     sys.argv = [enaml_file] + script_argv
@@ -59,7 +108,7 @@ def main():
     if requested in ns:
         component = ns[requested]
         descr = 'Enaml-run "%s" view' % requested
-        show_simple_view(component(), options.toolkit, descr)
+        show_simple_view(component(), toolkit, descr)
     elif 'main' in ns:
         ns['main']()
     else: