Merge pull request #72 from reinout/update-versions-file-without-show

Fix for #71 - looks good to me.

CHANGES.rst

@@ -4,7 +4,7 @@ Change History
 2.0.1 (2013-02-14)
 ==================
 
-- Fixe for distutils scripts installation on Python 3, related to
+- Fix for distutils scripts installation on Python 3, related to
   ``__pycache__`` directories.
 
 - Fixed: encoding data in non-entry-point-based scripts was lost.

src/zc/buildout/buildout.py

@@ -325,8 +325,8 @@ class Buildout(DictMixin):
         self.show_picked_versions = bool_option(options,
                                                 'show-picked-versions')
         self.update_versions_file = options['update-versions-file']
-        zc.buildout.easy_install.show_picked_versions(
-            self.show_picked_versions)
+        zc.buildout.easy_install.store_picked_versions(
+            self.show_picked_versions or self.update_versions_file)
 
         download_cache = options.get('download-cache')
         if download_cache:
@@ -996,8 +996,6 @@ class Buildout(DictMixin):
 
     def _print_picked_versions(self):
         Installer = zc.buildout.easy_install.Installer
-        if not self.show_picked_versions:
-            return
         if not Installer._picked_versions:
             # Don't print empty output.
             return
@@ -1016,11 +1014,13 @@ class Buildout(DictMixin):
 
         output.extend(required_output)
 
+        if self.show_picked_versions:
             print_("Versions had to be automatically picked.")
             print_("The following part definition lists the versions picked:")
             print_('\n'.join(output))
+
         if self.update_versions_file:
-            # Also write to the versions file.
+            # Write to the versions file.
             if os.path.exists(self.update_versions_file):
                 output[:1] = [
                     '',
@@ -1030,7 +1030,7 @@ class Buildout(DictMixin):
             f = open(self.update_versions_file, 'a')
             f.write('\n'.join(output))
             f.close()
-            print_("This information has been written to " +
+            print_("Picked versions have been written to " +
                    self.update_versions_file)
 
     def setup(self, args):

src/zc/buildout/easy_install.py

@@ -129,7 +129,7 @@ class Installer:
     _prefer_final = True
     _use_dependency_links = True
     _allow_picked_versions = True
-    _show_picked_versions = False
+    _store_picked_versions = False
 
     def __init__(self,
                  dest=None,
@@ -734,10 +734,10 @@ def allow_picked_versions(setting=None):
         Installer._allow_picked_versions = bool(setting)
     return old
 
-def show_picked_versions(setting=None):
-    old = Installer._show_picked_versions
+def store_picked_versions(setting=None):
+    old = Installer._store_picked_versions
     if setting is not None:
-        Installer._show_picked_versions = bool(setting)
+        Installer._store_picked_versions = bool(setting)
     return old
 
 
@@ -1260,7 +1260,7 @@ class MissingDistribution(zc.buildout.UserError):
 
 def _log_requirement(ws, req):
     if (not logger.isEnabledFor(logging.DEBUG) and
-        not Installer._show_picked_versions):
+        not Installer._store_picked_versions):
         # Sorting the working set and iterating over it's requirements
         # is expensive, so short circuit the work if it won't even be
         # logged.  When profiling a simple buildout with 10 parts with

src/zc/buildout/repeatable.txt

@@ -357,7 +357,7 @@ at the end.
     The following part definition lists the versions picked:
     [versions]
     spam = 2
-    This information has been written to my_versions.cfg
+    Picked versions have been written to my_versions.cfg
 
 The versions file now contains the extra pin:
 
@@ -370,6 +370,37 @@ And re-running buildout doesn't report any picked versions anymore:
     Updating foo.
     recipe v2
 
+If you've enabled ``update-versions-file`` but not ``show-picked-versions``,
+buildout will append the versions to your versions file anyway (without
+printing them to the console):
+
+    >>> write('my_versions.cfg',
+    ... '''
+    ... [versions]
+    ... distribute = 0.6.34
+    ... ''')
+    >>> write('buildout.cfg',
+    ... '''
+    ... [buildout]
+    ... parts = foo
+    ... extends = my_versions.cfg
+    ... update-versions-file = my_versions.cfg
+    ... find-links = %s
+    ... show-picked-versions = false
+    ...
+    ... [foo]
+    ... recipe = spam
+    ... ''' % join('recipe', 'dist'))
+    >>> print_(system(buildout), end='') # doctest: +ELLIPSIS
+    Updating foo.
+    recipe v2
+    Picked versions have been written to my_versions.cfg
+
+The versions file contains the extra pin:
+
+    >>> 'spam = 2' in open('my_versions.cfg').read()
+    True
+
 Because buildout now includes buildout-versions' (and the older
 buildout.dumppickedversions') functionality, it warns if these extensions are
 configured.