Refactor of platutils for cleanup.

Reduces duplication of common functionality, os-specific modules only
implement their own routines and the common code is provided by the
top-level public module.

IPython/Magic.py

@@ -2728,8 +2728,7 b' Defaulting color scheme to \'NoColor\'"""'
                 os.chdir(os.path.expanduser(ps))
                 if self.shell.rc.term_title:
                     #print 'set term title:',self.shell.rc.term_title  # dbg
-                    ttitle = 'IPy ' + abbrev_cwd()
-                    platutils.set_term_title(ttitle)
+                    platutils.set_term_title('IPy ' + abbrev_cwd())
             except OSError:
                 print sys.exc_info()[1]
             else:

IPython/platutils.py

@@ -3,13 +3,8 b''
 
 Importing this module should give you the implementations that are correct 
 for your operation system, from platutils_PLATFORMNAME module.
-
-$Id: ipstruct.py 1005 2006-01-12 08:39:26Z fperez $
-
-
 """
 
-
 #*****************************************************************************
 #       Copyright (C) 2001-2006 Fernando Perez <[e-mail]>
 #
@@ -21,15 +16,32 b' from IPython import Release'
 __author__  = '%s <%s>' % Release.authors['Ville']
 __license__ = Release.license
 
-import os,sys
+import os
+import sys
 
+# Import the platform-specific implementations
 if os.name == 'posix':
-    from platutils_posix import *
+    import platutils_posix as _platutils
 elif sys.platform == 'win32':
-    from platutils_win32 import *
+    import platutils_win32 as _platutils
 else:
-    from platutils_dummy import *
+    import platutils_dummy as _platutils
     import warnings
     warnings.warn("Platutils not available for platform '%s', some features may be missing" %
         os.name)
     del warnings
+
+
+# Functionality that's logically common to all platforms goes here, each
+# platform-specific module only provides the bits that are OS-dependent.
+
+def freeze_term_title():
+    _platutils.ignore_termtitle = True
+
+
+def set_term_title(title):
+    """Set terminal title using the necessary platform-dependent calls."""
+
+    if _platutils.ignore_termtitle:
+        return
+    _platutils.set_term_title(title)

IPython/platutils_dummy.py

@@ -3,13 +3,8 b''
 
 This has empty implementation of the platutils functions, used for 
 unsupported operating systems.
-
-$Id: ipstruct.py 1005 2006-01-12 08:39:26Z fperez $
-
-
 """
 
-
 #*****************************************************************************
 #       Copyright (C) 2001-2006 Fernando Perez <[e-mail]>
 #
@@ -21,9 +16,9 b' from IPython import Release'
 __author__  = '%s <%s>' % Release.authors['Ville']
 __license__ = Release.license
 
+# This variable is part of the expected API of the module:
+ignore_termtitle = True
 
-def _dummy(*args,**kw):
+def set_term_title(*args,**kw):
+    """Dummy no-op."""
     pass
-
-set_term_title = _dummy
-

IPython/platutils_posix.py

@@ -3,12 +3,8 b''
 
 Importing this module directly is not portable - rather, import platutils 
 to use these functions in platform agnostic fashion.
-
-$Id: ipstruct.py 1005 2006-01-12 08:39:26Z fperez $
-
 """
 
-
 #*****************************************************************************
 #       Copyright (C) 2001-2006 Fernando Perez <[e-mail]>
 #
@@ -31,9 +27,6 b' def _dummy_op(*a, **b):'
 def _set_term_title_xterm(title):
     """ Change virtual terminal title in xterm-workalikes """
 
-    if ignore_termtitle:
-        return
-    
     sys.stdout.write('\033]%d;%s\007' % (0,title))
 
 
@@ -41,7 +34,3 b" if os.environ.get('TERM','') == 'xterm':"
     set_term_title = _set_term_title_xterm
 else:
     set_term_title = _dummy_op
-
-def freeze_term_title():
-    global ignore_termtitle
-    ignore_termtitle = True

IPython/platutils_win32.py

@@ -3,12 +3,8 b''
 
 Importing this module directly is not portable - rather, import platutils 
 to use these functions in platform agnostic fashion.
-
-$Id: ipstruct.py 1005 2006-01-12 08:39:26Z fperez $
-
 """
 
-
 #*****************************************************************************
 #       Copyright (C) 2001-2006 Fernando Perez <[e-mail]>
 #
@@ -22,35 +18,30 b' __license__ = Release.license'
 
 import os
 
-ignore_termtitle = 0
+ignore_termtitle = False
 
 try:
     import ctypes
-    SetConsoleTitleW=ctypes.windll.kernel32.SetConsoleTitleW
-    SetConsoleTitleW.argtypes=[ctypes.c_wchar_p]
-    def _set_term_title(title):
-        """ Set terminal title using the ctypes"""
+
+    SetConsoleTitleW = ctypes.windll.kernel32.SetConsoleTitleW
+    SetConsoleTitleW.argtypes = [ctypes.c_wchar_p]
+    
+    def set_term_title(title):
+        """Set terminal title using ctypes to access the Win32 APIs."""
         SetConsoleTitleW(title)
 
 except ImportError:
-    def _set_term_title(title):
-        """ Set terminal title using the 'title' command """
-        curr=os.getcwd()
-        os.chdir("C:") #Cannot be on network share when issuing system commands
-        ret = os.system("title " + title)
-        os.chdir(curr)
+    def set_term_title(title):
+        """Set terminal title using the 'title' command."""
+        global ignore_termtitle
+
+        try:
+            # Cannot be on network share when issuing system commands
+            curr = os.getcwd()
+            os.chdir("C:")
+            ret = os.system("title " + title)
+        finally:
+            os.chdir(curr)
         if ret:
-            ignore_termtitle = 1
-
-def set_term_title(title):
-    """ Set terminal title using the 'title' command """
-    global ignore_termtitle
-
-    if ignore_termtitle:
-        return
-    _set_term_title(title)
-
-def freeze_term_title():
-    global ignore_termtitle
-    ignore_termtitle = 1
-
+            # non-zero return code signals error, don't try again
+            ignore_termtitle = True