1 files changed, 28 insertions, 4 deletions
diff --git a/ez_setup.py b/ez_setup.py
index 975b45c5..9715bdc7 100644
--- a/ez_setup.py
+++ b/ez_setup.py
@@ -16,7 +16,8 @@ import subprocess
 import platform
 import textwrap
 import contextlib
-import warnings
+import json
+import codecs
 
 from distutils import log
 
@@ -30,7 +31,8 @@ try:
 except ImportError:
     USER_SITE = None
 
-DEFAULT_VERSION = "18.7.2"
+LATEST = object()
+DEFAULT_VERSION = LATEST
 DEFAULT_URL = "https://pypi.python.org/packages/source/s/setuptools/"
 DEFAULT_SAVE_DIR = os.curdir
 
@@ -140,6 +142,7 @@ def use_setuptools(
     Return None. Raise SystemExit if the requested version
     or later cannot be installed.
     """
+    version = _resolve_version(version)
     to_dir = os.path.abspath(to_dir)
 
     # prior to importing, capture the module state for
@@ -222,8 +225,8 @@ def download_file_powershell(url, target):
     ps_cmd = (
         "[System.Net.WebRequest]::DefaultWebProxy.Credentials = "
         "[System.Net.CredentialCache]::DefaultCredentials; "
-        "(new-object System.Net.WebClient).DownloadFile(%(url)r, %(target)r)"
-        % vars()
+        '(new-object System.Net.WebClient).DownloadFile("%(url)s", "%(target)s")'
+        % locals()
     )
     cmd = [
         'powershell',
@@ -321,6 +324,7 @@ def download_setuptools(
     ``downloader_factory`` should be a function taking no arguments and
     returning a function for downloading a URL to a target.
     """
+    version = _resolve_version(version)
     # making sure we use the absolute path
     to_dir = os.path.abspath(to_dir)
     zip_name = "setuptools-%s.zip" % version
@@ -333,6 +337,26 @@ def download_setuptools(
     return os.path.realpath(saveto)
 
 
+def _resolve_version(version):
+    """
+    Resolve LATEST version
+    """
+    if version is not LATEST:
+        return version
+
+    resp = urlopen('https://pypi.python.org/pypi/setuptools/json')
+    with contextlib.closing(resp):
+        try:
+            charset = resp.info().get_content_charset()
+        except Exception:
+            # Python 2 compat; assume UTF-8
+            charset = 'UTF-8'
+        reader = codecs.getreader(charset)
+        doc = json.load(reader(resp))
+
+    return str(doc['info']['version'])
+
+
 def _build_install_args(options):
     """
     Build the arguments to 'python setup.py install' on the setuptools package.