Add a rough draft of Distribution.install_on(), to let others experiment

with 'require()' before the "official" version is complete.

--HG--
branch : setuptools
extra : convert_revision : svn%3A6015fed2-1504-0410-9fe1-9d1591cc4771/sandbox/trunk/setuptools%4041010

pkg_resources.py

@@ -417,7 +417,6 @@ def require(*requirements):
     XXX This doesn't work yet, because:
 
         * get_distro_source() isn't implemented
-        * Distribution.install_on() isn't implemented
         * AvailableDistributions.scan() is untested
 
     There may be other things missing as well, but this definitely won't work
@@ -447,6 +446,7 @@ def require(*requirements):
 
 
 
+
 
 
 class DefaultProvider:
@@ -846,6 +846,11 @@ class Distribution(object):
                 raise InvalidOption("No such option", self, opt)
         return deps
 
+    def install_on(self,path=None):
+        # XXX this needs to interface with namespace packages and such
+        if path is None: path = sys.path
+        if self.path not in path:
+            path.append(self.path)
 
 
 def _sort_dists(dists):
@@ -854,11 +859,6 @@ def _sort_dists(dists):
     dists[::-1] = [d for v,d in tmp]
 
 
-
-
-
-
-
 def parse_requirements(strs):
     """Yield ``Requirement`` objects for each specification in `strs`