Pulled in lelit's pull request #172 to add some fixes and to merge with master

CHANGES.rst

@@ -40,6 +40,14 @@ Change History
   configuration so that tests run much quicker so that buildout is easier and
   quicker to develop.
 
+- Treat ``download-cache`` and ``eggs-directory`` in a special manner:
+
+  a) they can be relative paths, relative to the location of the configuration
+     file that defines them
+
+  b) the can be in the form ``~/subdir``, with the usual convention that the
+     ``~`` char means the home directory of the user executing the buildout
+
 2.3.1 (2014-12-16)
 ==================
 

DEVELOPERS.txt

@@ -7,6 +7,10 @@ When you're developing buildout itself, you need to know two things:
   will find your already-installed setuptools, leading to test differences
   when setuptools' presence is explicitly tested.
 
+- Also the presence of ``~/.buildout/default.cfg`` may interfere with the
+  tests so you may want to temporarily rename it so that it does not get in
+  the way.
+
 - Don't bootstrap with ``python bootstrap/bootstrap.py`` but with ``python
   dev.py``.
 

src/zc/buildout/buildout.py

@@ -253,6 +253,36 @@ class Buildout(DictMixin):
                  if k not in versions
                  ))
 
+        # Absolutize some particular directory, handling also the ~/foo form,
+        # and considering the location of the configuration file that generated
+        # the setting as the base path, falling back to the main configuration
+        # file location
+        for name in ('download-cache', 'eggs-directory', 'extends-cache'):
+            if name in data['buildout']:
+                origdir, src = data['buildout'][name]
+                if '${' in origdir:
+                    continue
+                if not os.path.isabs(origdir):
+                    if src in ('DEFAULT_VALUE',
+                               'COMPUTED_VALUE',
+                               'COMMAND_LINE_VALUE'):
+                        if 'directory' in data['buildout']:
+                            basedir = data['buildout']['directory'][0]
+                        else:
+                            basedir = self._buildout_dir
+                    else:
+                        if _isurl(src):
+                            raise zc.buildout.UserError(
+                                'Setting "%s" to a non absolute location ("%s") '
+                                'within a\n'
+                                'remote configuration file ("%s") is ambiguous.' % (
+                                    name, origdir, src))
+                        basedir = os.path.dirname(src)
+                    absdir = os.path.expanduser(origdir)
+                    if not os.path.isabs(absdir):
+                        absdir = os.path.join(basedir, absdir)
+                    data['buildout'][name] = (absdir, src)
+
         self._annotated = copy.deepcopy(data)
         self._raw = _unannotate(data)
         self._data = {}
@@ -351,12 +381,8 @@ class Buildout(DictMixin):
         download_cache = options.get('download-cache')
         if download_cache:
             download_cache = os.path.join(options['directory'], download_cache)
-            if not os.path.isdir(download_cache):
-                raise zc.buildout.UserError(
-                    'The specified download cache:\n'
-                    '%r\n'
-                    "Doesn't exist.\n"
-                    % download_cache)
+            if not os.path.exists(download_cache):
+                os.mkdir(download_cache)
             download_cache = os.path.join(download_cache, 'dist')
             if not os.path.isdir(download_cache):
                 os.mkdir(download_cache)

src/zc/buildout/buildout.txt

@@ -810,7 +810,7 @@ COMMAND_LINE_VALUE).
         DEFAULT_VALUE
     directory= /sample-buildout
         COMPUTED_VALUE
-    eggs-directory= eggs
+    eggs-directory= /sample-buildout/eggs
         DEFAULT_VALUE
     executable= ...
         DEFAULT_VALUE

src/zc/buildout/downloadcache.txt

@@ -139,3 +139,78 @@ install-from-cache option set to true:
     Getting distribution for 'demoneeded'.
     Got demoneeded 1.1.
     Generated script '/sample-buildout/bin/demo'.
+
+Auto-creation of download cache directory
+-----------------------------------------
+
+With zc.buildout version 2.2.2 or higher the cache directory is automatically
+created, provided it is within an already existing directory::
+
+    >>> write('buildout.cfg',
+    ... '''
+    ... [buildout]
+    ... parts =
+    ... download-cache = %(cache)s/newdir
+    ... ''' % globals())
+
+    >>> print_(system(buildout), end='')
+    Uninstalling eggs.
+
+    >>> ls(cache)
+    d  dist
+    d  newdir
+
+Using relative paths
+--------------------
+
+You can use a relative path for ``download-cache`` (the same logic is applied to
+``eggs-directory`` and to ``extends-cache`` too) and in such case it is considered
+relative to the location of the configuration file that sets its value.
+
+As an example, we create a ``base.cfg`` configuration in a different directory::
+
+    >>> basedir = tmpdir('basecfg')
+    >>> write(basedir, 'base.cfg',
+    ... '''
+    ... [buildout]
+    ... download-cache = cache
+    ... ''')
+
+and a ``buildout.cfg`` that extends from there::
+
+    >>> write('buildout.cfg',
+    ... '''
+    ... [buildout]
+    ... extends = %(basedir)s/base.cfg
+    ... parts =
+    ... ''' % globals())
+
+    >>> dummy = system(buildout)
+    >>> ls(basedir)
+    -  base.cfg
+    d  cache
+
+Of course this cannot be used when the base configuration is not on the local
+filesystem because it wouldn't make any sense having a remote cache::
+
+    >>> server_data = tmpdir('server_data')
+    >>> server_url = start_server(server_data)
+    >>> cd(sample_buildout)
+
+    >>> write(server_data, 'base.cfg', """\
+    ... [buildout]
+    ... download-cache = cache
+    ... """)
+
+    >>> write('buildout.cfg',
+    ... '''
+    ... [buildout]
+    ... extends = %(server_url)s/base.cfg
+    ... parts =
+    ... ''' % globals())
+
+    >>> print_(system(buildout), end='') # doctest: +ELLIPSIS
+    While:
+      Initializing.
+    Error: Setting "download-cache" to a non absolute location ("cache") within a
+    remote configuration file...