[Distutils] patches: ez_setup.py: don't import setuptools into your current address space in order to learn its version number

[zooko]

Folks:

We're gradually converting the allmydata.org tahoe project [1] and  
its spin-off packages to use setuptools.  One problem that comes up  
is that ez_setup.py might require a newer version of setuptools than  
the version of setuptools already installed.

For example, although Tahoe currently uses setuptools to manage its  
dependencies on zfec, foolscap, and nevow [2], but if we execute  
simplejson's ez_setup.py then it requires setuptools v0.6c7 and  
refuses to proceed if an earlier version is installed.

One solution for this problem could be for the packager of simplejson  
(Bob Ippolito) to use the "min_version" patch that we contributed to  
ez_setup.py [3].  This is assuming that simplejson doesn't actually  
*require* the latest version of setuptools, and we could successfully  
install with a slightly older version, but what if a package actually  
does require a newer version of setuptools than the one that is  
already installed?

The following patch was created by Tahoe contributor Arno Washck and  
then modified by me in order to get around such a problem.  The idea  
is simple enough -- reload setuptools.  There may be some subtleties  
that we still need to work out.  This patch hasn't been tested in its  
current form.

--- ez_setup.py~	2007-09-10 12:36:30.000000000 -0600
+++ ez_setup.py	2007-09-18 15:15:23.000000000 -0600
@@ -95,13 +95,9 @@
          pkg_resources.require("setuptools>="+version)
      except pkg_resources.VersionConflict, e:
-        # XXX could we install in a subprocess here?
-        print >>sys.stderr, (
-            "The required version of setuptools (>=%s) is not  
available, and\n"
-            "can't be installed while this script is running. Please  
install\n"
-            " a more recent version first.\n\n(Currently using %r)"
-        ) % (version, e.args[0])
-        sys.exit(2)
+        egg = download_setuptools(version, download_base, to_dir,  
download_delay)
+        sys.path.insert(0, egg)
+        reload(setuptools); setuptools.bootstrap_install_from = egg
def download_setuptools(
      version=DEFAULT_VERSION, download_base=DEFAULT_URL,  
to_dir=os.curdir,

-------

An alternative idea figure out the version of the current install of  
setuptools without importing the package.  The following patch might  
accomplish that.  It is also not tested.

--- ez_setup.py~	2007-09-10 12:36:30.000000000 -0600
+++ ez_setup.py	2007-09-18 15:26:50.000000000 -0600
@@ -77,31 +77,13 @@
      this routine will print a message to ``sys.stderr`` and raise  
SystemExit in
      an attempt to abort the calling script.
      """
-    try:
-        import setuptools
-        if setuptools.__version__ == '0.0.1':
-            print >>sys.stderr, (
-            "You have an obsolete version of setuptools installed.   
Please\n"
-            "remove it from your system entirely before rerunning  
this script."
-            )
-            sys.exit(2)
-    except ImportError:
-        egg = download_setuptools(version, download_base, to_dir,  
download_delay)
-        sys.path.insert(0, egg)
-        import setuptools; setuptools.bootstrap_install_from = egg
-
+    verstr = os.system("python -c \"import setuptools;print  
setuptools.__version__\"")
      import pkg_resources
-    try:
-        pkg_resources.require("setuptools>="+version)
-    except pkg_resources.VersionConflict, e:
-        # XXX could we install in a subprocess here?
-        print >>sys.stderr, (
-            "The required version of setuptools (>=%s) is not  
available, and\n"
-            "can't be installed while this script is running. Please  
install\n"
-            " a more recent version first.\n\n(Currently using %r)"
-        ) % (version, e.args[0])
-        sys.exit(2)
+    if pkg_resources.parse_version(verstr) <  
pkg_resources.parse_version(version):
+        egg = download_setuptools(version, download_base, to_dir)
+        sys.path.insert(0, egg)
+        import setuptools; setuptools.bootstrap_install_from = egg
def download_setuptools(
      version=DEFAULT_VERSION, download_base=DEFAULT_URL,  
to_dir=os.curdir,

-------

Regards,

Zooko

[1] http://allmydata.org
[2] http://allmydata.org/trac/tahoe/browser/calcdeps.py
[3] http://mail.python.org/pipermail/distutils-sig/2007-September/ 
008257.html

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