Make single setup script work on Python 2 and Python 3.

setup2.py

@@ -20,17 +20,20 b' requires utilities which are not available under Windows."""'
 #-----------------------------------------------------------------------------
 # Minimal Python version sanity check
 #-----------------------------------------------------------------------------
+from __future__ import print_function
 
 import sys
 
 # This check is also made in IPython/__init__, don't forget to update both when
 # changing Python version requirements.
-if sys.version[0:3] < '2.6':
-    error = """\
-ERROR: 'IPython requires Python Version 2.6 or above.'
-Exiting."""
-    print >> sys.stderr, error
-    sys.exit(1)
+#~ if sys.version[0:3] < '2.6':
+    #~ error = """\
+#~ ERROR: 'IPython requires Python Version 2.6 or above.'
+#~ Exiting."""
+    #~ print >> sys.stderr, error
+    #~ sys.exit(1)
+
+PY3 = (sys.version_info[0] >= 3)
 
 # At least we're on the python version we need, move on.
 
@@ -50,8 +53,12 b" if os.path.exists('MANIFEST'): os.remove('MANIFEST')"
 
 from distutils.core import setup
 
+# On Python 3, we need distribute (new setuptools) to do the 2to3 conversion
+if PY3:
+    import setuptools
+
 # Our own imports
-from IPython.utils.path import target_update
+from setupbase import target_update
 
 from setupbase import (
     setup_args,
@@ -91,14 +98,14 b" if os.name == 'posix':"
 elif os.name in ['nt','dos']:
     os_name = 'windows'
 else:
-    print 'Unsupported operating system:',os.name
+    print('Unsupported operating system:',os.name)
     sys.exit(1)
 
 # Under Windows, 'sdist' has not been supported.  Now that the docs build with
 # Sphinx it might work, but let's not turn it on until someone confirms that it
 # actually works.
 if os_name == 'windows' and 'sdist' in sys.argv:
-    print 'The sdist command is not available under Windows.  Exiting.'
+    print('The sdist command is not available under Windows.  Exiting.')
     sys.exit(1)
 
 #-------------------------------------------------------------------------------
@@ -187,6 +194,11 b' packages = find_packages()'
 package_data = find_package_data()
 data_files = find_data_files()
 
+setup_args['cmdclass'] = {'build_py': record_commit_info('IPython')}
+setup_args['packages'] = packages
+setup_args['package_data'] = package_data
+setup_args['data_files'] = data_files
+
 #---------------------------------------------------------------------------
 # Handle scripts, dependencies, and setuptools specific things
 #---------------------------------------------------------------------------
@@ -247,6 +259,12 b" if 'setuptools' in sys.modules:"
         setup_args['options'] = {"bdist_wininst":
                                  {"install_script":
                                   "ipython_win_post_install.py"}}
+    
+    if PY3:
+        setuptools_extra_args['use_2to3'] = True
+        from setuptools.command.build_py import build_py
+        setup_args['cmdclass'] = {'build_py': record_commit_info('IPython', build_cmd=build_py)}
+        setuptools_extra_args['entry_points'] = find_scripts(True, suffix='3')
 else:
     # If we are running without setuptools, call this function which will
     # check for dependencies an inform the user what is needed.  This is
@@ -258,10 +276,6 b' else:'
 # Do the actual setup now
 #---------------------------------------------------------------------------
 
-setup_args['cmdclass'] = {'build_py': record_commit_info('IPython')}
-setup_args['packages'] = packages
-setup_args['package_data'] = package_data
-setup_args['data_files'] = data_files
 setup_args.update(setuptools_extra_args)
 
 def main():

setupbase.py

@@ -251,6 +251,44 b' def make_man_update_target(manpage):'
                locals() )
     return (manpath_gz, [manpath], gz_cmd)
 
+# The two functions below are copied from IPython.utils.path, so we don't need
+# to import IPython during setup, which fails on Python 3.
+
+def target_outdated(target,deps):
+    """Determine whether a target is out of date.
+
+    target_outdated(target,deps) -> 1/0
+
+    deps: list of filenames which MUST exist.
+    target: single filename which may or may not exist.
+
+    If target doesn't exist or is older than any file listed in deps, return
+    true, otherwise return false.
+    """
+    try:
+        target_time = os.path.getmtime(target)
+    except os.error:
+        return 1
+    for dep in deps:
+        dep_time = os.path.getmtime(dep)
+        if dep_time > target_time:
+            #print "For target",target,"Dep failed:",dep # dbg
+            #print "times (dep,tar):",dep_time,target_time # dbg
+            return 1
+    return 0
+
+
+def target_update(target,deps,cmd):
+    """Update a target with a given command given a list of dependencies.
+
+    target_update(target,deps,cmd) -> runs cmd if target is outdated.
+
+    This is just a wrapper around target_outdated() which calls the given
+    command if target is outdated."""
+
+    if target_outdated(target,deps):
+        system(cmd)
+
 #---------------------------------------------------------------------------
 # Find scripts
 #---------------------------------------------------------------------------

setupext/setupext.py

@@ -1,4 +1,5 b''
 # encoding: utf-8
+from __future__ import print_function
 
 __docformat__ = "restructuredtext en"
 
@@ -27,26 +28,26 b' def check_display(f):'
 
 @check_display
 def print_line(char='='):
-    print char * 76
+    print(char * 76)
 
 @check_display
 def print_status(package, status):
     initial_indent = "%22s: " % package
     indent = ' ' * 24
-    print fill(str(status), width=76,
+    print(fill(str(status), width=76,
                initial_indent=initial_indent,
-               subsequent_indent=indent)
+               subsequent_indent=indent))
 
 @check_display
 def print_message(message):
     indent = ' ' * 24 + "* "
-    print fill(str(message), width=76,
+    print(fill(str(message), width=76,
                initial_indent=indent,
-               subsequent_indent=indent)
+               subsequent_indent=indent))
 
 @check_display
 def print_raw(section):
-    print section
+    print(section)
 
 #-------------------------------------------------------------------------------
 # Tests for specific packages