Cache eggs required for building in .eggs dir

This makes it so that these eggs don't prevent `install_requires` from
installing these packages.

Fixes ticket #80; workaround for ticket #209

3 files changed, 50 insertions, 2 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index d7e3369d..b1b7f2e8 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -2,6 +2,18 @@
 CHANGES
 =======
 
+----------
+Unreleased
+----------
+
+* Issue #80, #209: Eggs that are downloaded for ``setup_requires``,
+  ``test_requires``, etc. are now placed in a ``.eggs`` directory instead of
+  the package root directory. This is a better place for them as it doesn't
+  cause later phases of setuptools to think that the package is already
+  installed and then not install the package permanently in the environment
+  (See #209).
+
+
 ---
 6.1
 ---
diff --git a/setuptools/dist.py b/setuptools/dist.py
index 8b36f67c..2d9da8c4 100644
--- a/setuptools/dist.py
+++ b/setuptools/dist.py
@@ -14,7 +14,8 @@ from distutils.errors import (DistutilsOptionError, DistutilsPlatformError,
     DistutilsSetupError)
 
 from setuptools.depends import Require
-from setuptools.compat import basestring, PY2
+from setuptools.compat import basestring, PY2, unicode
+from setuptools import win32
 import pkg_resources
 
 def _get_unpatched(cls):
@@ -305,6 +306,21 @@ class Distribution(_Distribution):
         else:
             self.convert_2to3_doctests = []
 
+    def get_egg_cache_dir(self):
+        egg_cache_dir = os.path.join(os.curdir, '.eggs')
+        if not os.path.exists(egg_cache_dir):
+            os.mkdir(egg_cache_dir)
+            win32.hide_file(unicode(egg_cache_dir))
+            readme_txt_filename = os.path.join(egg_cache_dir, 'README.txt')
+            with open(readme_txt_filename, 'w') as f:
+                f.write('This directory contains eggs that were downloaded '
+                        'by setuptools to build, test, and run plug-ins.\n\n')
+                f.write('This directory caches those eggs to prevent '
+                        'repeated downloads.\n\n')
+                f.write('However, it is safe to delete this directory.\n\n')
+
+        return egg_cache_dir
+
     def fetch_build_egg(self, req):
         """Fetch an egg needed for building"""
 
@@ -328,8 +344,9 @@ class Distribution(_Distribution):
                 if 'find_links' in opts:
                     links = opts['find_links'][1].split() + links
                 opts['find_links'] = ('setup', links)
+            install_dir = self.get_egg_cache_dir()
             cmd = easy_install(
-                dist, args=["x"], install_dir=os.curdir, exclude_scripts=True,
+                dist, args=["x"], install_dir=install_dir, exclude_scripts=True,
                 always_copy=False, build_directory=None, editable=False,
                 upgrade=False, multi_version=True, no_report=True, user=False
             )
diff --git a/setuptools/win32.py b/setuptools/win32.py
new file mode 100644
index 00000000..fd373009
--- /dev/null
+++ b/setuptools/win32.py
@@ -0,0 +1,19 @@
+# From http://stackoverflow.com/questions/19622133/python-set-hide-attribute-on-folders-in-windows-os
+
+import ctypes
+
+
+def hide_file(path):
+    """Sets the hidden attribute on a file or directory
+
+    `path` must be unicode; be careful that you escape backslashes or use raw
+    string literals - e.g.: `u'G:\\Dir\\folder1'` or `ur'G:\Dir\folder1'`.
+    """
+
+    SetFileAttributesW = ctypes.windll.kernel32.SetFileAttributesW
+
+    FILE_ATTRIBUTE_HIDDEN = 0x02
+
+    ret = SetFileAttributesW(path, FILE_ATTRIBUTE_HIDDEN)
+    if not ret:
+        raise ctypes.WinError()