setup.py: keep Python 2.3 compatibility

Though we only support Python 2.4 or greater, we should keep setup.py
compatible with earlier versions on the syntactic level. Otherwise
people will simply get a SyntaxError when trying to install Mercurial
with an old version of Python. With this change, the setup.py file can
be imported with Python 2.3 and we then issue a friendly error message
when we detect that Python is too old.

setup.py

@@ -1,285 +1,285
 #!/usr/bin/env python
 #
 # This is the mercurial setup script.
 #
 # 'python setup.py install', or
 # 'python setup.py --help' for more options
 
 import sys
 if not hasattr(sys, 'version_info') or sys.version_info < (2, 4, 0, 'final'):
     raise SystemExit("Mercurial requires Python 2.4 or later.")
 
 # Solaris Python packaging brain damage
 try:
     import hashlib
     sha = hashlib.sha1()
 except:
     try:
         import sha
     except:
         raise SystemExit(
             "Couldn't import standard hashlib (incomplete Python install).")
 
 try:
     import zlib
 except:
     raise SystemExit(
         "Couldn't import standard zlib (incomplete Python install).")
 
 import os, subprocess, time
 import shutil
 import tempfile
 from distutils.core import setup, Extension
 from distutils.dist import Distribution
 from distutils.command.install_data import install_data
 from distutils.command.build import build
 from distutils.command.build_py import build_py
 from distutils.spawn import spawn, find_executable
 from distutils.ccompiler import new_compiler
 
 extra = {}
 scripts = ['hg']
 if os.name == 'nt':
     scripts.append('contrib/win32/hg.bat')
 
 # simplified version of distutils.ccompiler.CCompiler.has_function
 # that actually removes its temporary files.
 def has_function(cc, funcname):
     tmpdir = tempfile.mkdtemp(prefix='hg-install-')
     devnull = oldstderr = None
     try:
         try:
             fname = os.path.join(tmpdir, 'funcname.c')
             f = open(fname, 'w')
             f.write('int main(void) {\n')
             f.write('    %s();\n' % funcname)
             f.write('}\n')
             f.close()
             # Redirect stderr to /dev/null to hide any error messages
             # from the compiler.
             # This will have to be changed if we ever have to check
             # for a function on Windows.
             devnull = open('/dev/null', 'w')
             oldstderr = os.dup(sys.stderr.fileno())
             os.dup2(devnull.fileno(), sys.stderr.fileno())
             objects = cc.compile([fname], output_dir=tmpdir)
             cc.link_executable(objects, os.path.join(tmpdir, "a.out"))
         except:
             return False
         return True
     finally:
         if oldstderr is not None:
             os.dup2(oldstderr, sys.stderr.fileno())
         if devnull is not None:
             devnull.close()
         shutil.rmtree(tmpdir)
 
 # py2exe needs to be installed to work
 try:
     import py2exe
 
     # Help py2exe to find win32com.shell
     try:
         import modulefinder
         import win32com
         for p in win32com.__path__[1:]: # Take the path to win32comext
             modulefinder.AddPackagePath("win32com", p)
         pn = "win32com.shell"
         __import__(pn)
         m = sys.modules[pn]
         for p in m.__path__[1:]:
             modulefinder.AddPackagePath(pn, p)
     except ImportError:
         pass
 
     extra['console'] = ['hg']
 
 except ImportError:
     pass
 
 def runcmd(cmd, env):
     p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                          stderr=subprocess.PIPE, env=env)
     out, err = p.communicate()
     # If root is executing setup.py, but the repository is owned by
     # another user (as in "sudo python setup.py install") we will get
     # trust warnings since the .hg/hgrc file is untrusted. That is
     # fine, we don't want to load it anyway.  Python may warn about
     # a missing __init__.py in mercurial/locale, we also ignore that.
     err = [e for e in err.splitlines()
            if not e.startswith('Not trusting file') \
               and not e.startswith('warning: Not importing')]
     if err:
         return ''
     return out
 
 version = ''
 
 if os.path.isdir('.hg'):
     # Execute hg out of this directory with a custom environment which
     # includes the pure Python modules in mercurial/pure. We also take
     # care to not use any hgrc files and do no localization.
     pypath = ['mercurial', os.path.join('mercurial', 'pure')]
     env = {'PYTHONPATH': os.pathsep.join(pypath),
            'HGRCPATH': '',
            'LANGUAGE': 'C'}
     if 'LD_LIBRARY_PATH' in os.environ:
         env['LD_LIBRARY_PATH'] = os.environ['LD_LIBRARY_PATH']
     if 'SystemRoot' in os.environ:
         # Copy SystemRoot into the custom environment for Python 2.6
         # under Windows. Otherwise, the subprocess will fail with
         # error 0xc0150004. See: http://bugs.python.org/issue3440
         env['SystemRoot'] = os.environ['SystemRoot']
     cmd = [sys.executable, 'hg', 'id', '-i', '-t']
     l = runcmd(cmd, env).split()
     while len(l) > 1 and l[-1][0].isalpha(): # remove non-numbered tags
         l.pop()
     if len(l) > 1: # tag found
         version = l[-1]
         if l[0].endswith('+'): # propagate the dirty status to the tag
             version += '+'
     elif len(l) == 1: # no tag found
         cmd = [sys.executable, 'hg', 'parents', '--template',
                '{latesttag}+{latesttagdistance}-']
         version = runcmd(cmd, env) + l[0]
     if version.endswith('+'):
         version += time.strftime('%Y%m%d')
 elif os.path.exists('.hg_archival.txt'):
-    kw = dict([t.strip() for t in l.split(':', 1)]
-              for l in open('.hg_archival.txt'))
+    kw = dict([[t.strip() for t in l.split(':', 1)]
+               for l in open('.hg_archival.txt')])
     if 'tag' in kw:
         version =  kw['tag']
     elif 'latesttag' in kw:
         version = '%(latesttag)s+%(latesttagdistance)s-%(node).12s' % kw
     else:
         version = kw.get('node', '')[:12]
 
 if version:
     f = open("mercurial/__version__.py", "w")
     f.write('# this file is autogenerated by setup.py\n')
     f.write('version = "%s"\n' % version)
     f.close()
 
 
 try:
     from mercurial import __version__
     version = __version__.version
 except ImportError:
     version = 'unknown'
 
 class install_package_data(install_data):
     def finalize_options(self):
         self.set_undefined_options('install',
                                    ('install_lib', 'install_dir'))
         install_data.finalize_options(self)
 
 class build_mo(build):
 
     description = "build translations (.mo files)"
 
     def run(self):
         if not find_executable('msgfmt'):
             self.warn("could not find msgfmt executable, no translations "
                      "will be built")
             return
 
         podir = 'i18n'
         if not os.path.isdir(podir):
             self.warn("could not find %s/ directory" % podir)
             return
 
         join = os.path.join
         for po in os.listdir(podir):
             if not po.endswith('.po'):
                 continue
             pofile = join(podir, po)
             modir = join('locale', po[:-3], 'LC_MESSAGES')
             mofile = join(modir, 'hg.mo')
             cmd = ['msgfmt', '-v', '-o', mofile, pofile]
             if sys.platform != 'sunos5':
                 # msgfmt on Solaris does not know about -c
                 cmd.append('-c')
             self.mkpath(modir)
             self.make_file([pofile], mofile, spawn, (cmd,))
             self.distribution.data_files.append((join('mercurial', modir),
                                                  [mofile]))
 
 build.sub_commands.append(('build_mo', None))
 
 Distribution.pure = 0
 Distribution.global_options.append(('pure', None, "use pure (slow) Python "
                                     "code instead of C extensions"))
 
 class hg_build_py(build_py):
 
     def finalize_options(self):
         build_py.finalize_options(self)
 
         if self.distribution.pure:
             if self.py_modules is None:
                 self.py_modules = []
             for ext in self.distribution.ext_modules:
                 if ext.name.startswith("mercurial."):
                     self.py_modules.append("mercurial.pure.%s" % ext.name[10:])
             self.distribution.ext_modules = []
 
     def find_modules(self):
         modules = build_py.find_modules(self)
         for module in modules:
             if module[0] == "mercurial.pure":
                 if module[1] != "__init__":
                     yield ("mercurial", module[1], module[2])
             else:
                 yield module
 
 cmdclass = {'install_data': install_package_data,
             'build_mo': build_mo,
             'build_py': hg_build_py}
 
 ext_modules=[
     Extension('mercurial.base85', ['mercurial/base85.c']),
     Extension('mercurial.bdiff', ['mercurial/bdiff.c']),
     Extension('mercurial.diffhelpers', ['mercurial/diffhelpers.c']),
     Extension('mercurial.mpatch', ['mercurial/mpatch.c']),
     Extension('mercurial.parsers', ['mercurial/parsers.c']),
     Extension('mercurial.osutil', ['mercurial/osutil.c']),
     ]
 
 packages = ['mercurial', 'mercurial.hgweb', 'hgext', 'hgext.convert',
             'hgext.highlight', 'hgext.zeroconf', ]
 
 if sys.platform == 'linux2' and os.uname()[2] > '2.6':
     # The inotify extension is only usable with Linux 2.6 kernels.
     # You also need a reasonably recent C library.
     cc = new_compiler()
     if has_function(cc, 'inotify_add_watch'):
         ext_modules.append(Extension('hgext.inotify.linux._inotify',
                                      ['hgext/inotify/linux/_inotify.c']))
         packages.extend(['hgext.inotify', 'hgext.inotify.linux'])
 
 datafiles = []
 for root in ('templates', 'i18n', 'help'):
     for dir, dirs, files in os.walk(root):
         dirs[:] = [x for x in dirs if not x.startswith('.')]
         files = [x for x in files if not x.startswith('.')]
         datafiles.append((os.path.join('mercurial', dir),
                           [os.path.join(dir, file_) for file_ in files]))
 
 setup(name='mercurial',
       version=version,
       author='Matt Mackall',
       author_email='[e-mail]',
       url='http://mercurial.selenic.com/',
       description='Scalable distributed SCM',
       license='GNU GPL',
       scripts=scripts,
       packages=packages,
       ext_modules=ext_modules,
       data_files=datafiles,
       cmdclass=cmdclass,
       options=dict(py2exe=dict(packages=['hgext', 'email']),
                    bdist_mpkg=dict(zipdist=True,
                                    license='COPYING',
                                    readme='contrib/macosx/Readme.html',
                                    welcome='contrib/macosx/Welcome.html')),
       **extra)