Allow distutils extensions to define new kinds of metadata that can be

written to EGG-INFO.  Extensible applications and frameworks can thus make
it possible for plugin projects to supply setup() metadata that can then
be used by the application or framework.

--HG--
branch : setuptools
extra : convert_revision : svn%3A6015fed2-1504-0410-9fe1-9d1591cc4771/sandbox/trunk/setuptools%4041183

4 files changed, 232 insertions, 111 deletions

diff --git a/setup.py b/setup.py
index e56e15f9..038c86fe 100755
--- a/setup.py
+++ b/setup.py
@@ -40,7 +40,6 @@ setup(
     scripts = ['easy_install.py'],
     
     zip_safe = False,   # We want 'python -m easy_install' to work  :(
-
     entry_points = {
         "distutils.commands" : [
             "%(cmd)s = setuptools.command.%(cmd)s:%(cmd)s" % locals()
@@ -50,13 +49,23 @@ setup(
             "eager_resources    = setuptools.dist:assert_string_list",
             "namespace_packages = setuptools.dist:check_nsp",
             "extras_require     = setuptools.dist:check_extras",
+            "install_requires   = setuptools.dist:check_install_requires",
             "entry_points       = setuptools.dist:check_entry_points",
             "test_suite         = setuptools.dist:check_test_suite",
             "zip_safe           = setuptools.dist:assert_bool",
-        ]
+        ],
+        "egg_info.writers": [
+            "PKG-INFO = setuptools.command.egg_info:write_pkg_info",
+            "requires.txt = setuptools.command.egg_info:write_requirements",
+            "entry_points.txt = setuptools.command.egg_info:write_entries",
+            "eager_resources.txt = setuptools.command.egg_info:write_arg",
+            "namespace_packages.txt = setuptools.command.egg_info:write_arg",
+            "top_level.txt = setuptools.command.egg_info:write_toplevel_names",
+            "depends.txt = setuptools.command.egg_info:warn_depends_obsolete",
+        ],
     },
-
-    setup_requires = ['setuptools>=0.6a0'],
+    # uncomment for testing
+    # setup_requires = ['setuptools>=0.6a0'],
 
     classifiers = [f.strip() for f in """
     Development Status :: 3 - Alpha
@@ -68,23 +77,6 @@ setup(
     Topic :: Software Development :: Libraries :: Python Modules
     Topic :: System :: Archiving :: Packaging
     Topic :: System :: Systems Administration
-    Topic :: Utilities
-    """.splitlines() if f.strip()]
+    Topic :: Utilities""".splitlines() if f.strip()]
 )
 
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
diff --git a/setuptools.egg-info/entry_points.txt b/setuptools.egg-info/entry_points.txt
index 82f0990e..c6b3f595 100755
--- a/setuptools.egg-info/entry_points.txt
+++ b/setuptools.egg-info/entry_points.txt
@@ -1,11 +1,21 @@
 [distutils.setup_keywords]
 entry_points = setuptools.dist:check_entry_points
 extras_require = setuptools.dist:check_extras
+install_requires = setuptools.dist:check_install_requires
 namespace_packages = setuptools.dist:check_nsp
 test_suite = setuptools.dist:check_test_suite
 eager_resources = setuptools.dist:assert_string_list
 zip_safe = setuptools.dist:assert_bool
 
+[egg_info.writers]
+requires.txt = setuptools.command.egg_info:write_requirements
+PKG-INFO = setuptools.command.egg_info:write_pkg_info
+eager_resources.txt = setuptools.command.egg_info:write_arg
+top_level.txt = setuptools.command.egg_info:write_toplevel_names
+namespace_packages.txt = setuptools.command.egg_info:write_arg
+entry_points.txt = setuptools.command.egg_info:write_entries
+depends.txt = setuptools.command.egg_info:warn_depends_obsolete
+
 [distutils.commands]
 rotate = setuptools.command.rotate:rotate
 develop = setuptools.command.develop:develop
diff --git a/setuptools.txt b/setuptools.txt
index 872830aa..66881d6c 100755
--- a/setuptools.txt
+++ b/setuptools.txt
@@ -622,6 +622,21 @@ invoking app or framework can ignore such errors if it wants to make an entry
 point optional if a requirement isn't installed.)
 
 
+Defining Additional Metadata
+----------------------------
+
+Some extensible applications and frameworks may need to define their own kinds
+of metadata to include in eggs, which they can then access using the
+``pkg_resources`` metadata APIs.  Ordinarily, this is done by having plugin
+developers include additional files in their ``ProjectName.egg-info``
+directory.  However, since it can be tedious to create such files by hand, you
+may want to create a distutils extension that will create the necessary files
+from arguments to ``setup()``, in much the same way that ``setuptools`` does
+for many of the ``setup()`` arguments it adds.  See the section below on
+`Creating distutils Extensions`_ for more details, especially the subsection on
+`Adding new EGG-INFO Files`_.
+
+
 "Development Mode"
 ==================
 
@@ -1301,6 +1316,14 @@ the project's source directory or metadata should get it from this setting:
     ``package_dir`` argument to the ``setup()`` function, if any.  If there is
     no ``package_dir`` set, this option defaults to the current directory.
 
+In addition to writing the core egg metadata defined by ``setuptools`` and
+required by ``pkg_resources``, this command can be extended to write other
+metadata files as well, by defining entry points in the ``egg_info.writers``
+group.  See the section on `Adding new EGG-INFO Files`_ below for more details.
+Note that using additional metadata writers may require you to include a
+``setup_requires`` argument to ``setup()`` in order to ensure that the desired
+writers are available on ``sys.path``.
+
 
 .. _rotate:
 
@@ -1639,6 +1662,60 @@ sufficient to define the entry points in your extension, as long as the setup
 script lists your extension in its ``setup_requires`` argument.
 
 
+Adding new EGG-INFO Files
+-------------------------
+
+Some extensible applications or frameworks may want to allow third parties to
+develop plugins with application or framework-specific metadata included in
+the plugins' EGG-INFO directory, for easy access via the ``pkg_resources``
+metadata API.  The easiest way to allow this is to create a distutils extension
+to be used from the plugin projects' setup scripts (via ``setup_requires``)
+that defines a new setup keyword, and then uses that data to write an EGG-INFO
+file when the ``egg_info`` command is run.
+
+The ``egg_info`` command looks for extension points in an ``egg_info.writers``
+group, and calls them to write the files.  Here's a simple example of a
+distutils extension defining a setup argument ``foo_bar``, which is a list of
+lines that will be written to ``foo_bar.txt`` in the EGG-INFO directory of any
+project that uses the argument::
+
+    setup(
+        # ...
+        entry_points = {
+            "distutils.setup_keywords": [
+                "foo_bar = setuptools.dist:assert_string_list",
+            ],
+            "egg_info.writers": [
+                "foo_bar.txt = setuptools.command.egg_info:write_arg",
+            ],
+        },
+    )
+
+This simple example makes use of two utility functions defined by setuptools
+for its own use: a routine to validate that a setup keyword is a sequence of
+strings, and another one that looks up a setup argument and writes it to
+a file.  Here's what the writer utility looks like::
+
+    def write_arg(cmd, basename, filename):
+        argname = os.path.splitext(basename)[0]
+        value = getattr(cmd.distribution, argname, None)
+        if value is not None:
+            value = '\n'.join(value)+'\n'
+        cmd.write_or_delete_file(argname, filename, value)
+
+As you can see, ``egg_info.writers`` entry points must be a function taking
+three arguments: a ``egg_info`` command instance, the basename of the file to
+write (e.g. ``foo_bar.txt``), and the actual full filename that should be
+written to.
+
+In general, writer functions should honor the command object's ``dry_run``
+setting when writing files, and use the ``distutils.log`` object to do any
+console output.  The easiest way to conform to this requirement is to use
+the ``cmd`` object's ``write_file()``, ``delete_file()``, and
+``write_or_delete_file()`` methods exclusively for your file operations.  See
+those methods' docstrings for more details.
+
+
 Subclassing ``Command``
 -----------------------
 
@@ -1709,9 +1786,10 @@ Release Notes/Change History
    ``setup_requires`` allows you to automatically find and download packages
    that are needed in order to *build* your project (as opposed to running it).
 
- * ``setuptools`` now finds its commands and ``setup()`` argument validators
-   using entry points, so that they are extensible by third-party packages.
-   See `Creating distutils Extensions`_ above for more details.
+ * ``setuptools`` now finds its commands, ``setup()`` argument validators, and
+   metadata writers using entry points, so that they can be extended by
+   third-party packages.  See `Creating distutils Extensions`_ above for more
+   details.
 
  * The vestigial ``depends`` command has been removed.  It was never finished
    or documented, and never would have worked without EasyInstall - which it
diff --git a/setuptools/command/egg_info.py b/setuptools/command/egg_info.py
index 7d0a1473..ae3c762b 100755
--- a/setuptools/command/egg_info.py
+++ b/setuptools/command/egg_info.py
@@ -8,7 +8,7 @@ from setuptools import Command
 from distutils.errors import *
 from distutils import log
 from pkg_resources import parse_requirements, safe_name, \
-    safe_version, yield_lines, EntryPoint
+    safe_version, yield_lines, EntryPoint, iter_entry_points
 
 class egg_info(Command):
 
@@ -80,47 +80,55 @@ class egg_info(Command):
 
 
 
-    def run(self):
-        # Make the .egg-info directory, then write PKG-INFO and requires.txt
-        self.mkpath(self.egg_info)
-        log.info("writing %s" % os.path.join(self.egg_info,'PKG-INFO'))
-
-        if not self.dry_run:
-            metadata = self.distribution.metadata
-            metadata.version, oldver = self.egg_version, metadata.version
-            metadata.name, oldname   = self.egg_name, metadata.name
-            try:
-                # write unescaped data to PKG-INFO, so older pkg_resources
-                # can still parse it
-                metadata.write_pkg_info(self.egg_info)
-            finally:
-                metadata.name, metadata.version = oldname, oldver
-        self.write_entry_points()
-        self.write_requirements()
-        self.write_toplevel_names()
-        self.write_or_delete_dist_arg('namespace_packages')
-        self.write_or_delete_dist_arg('eager_resources')
-        if os.path.exists(os.path.join(self.egg_info,'depends.txt')):
-            log.warn(
-                "WARNING: 'depends.txt' is not used by setuptools 0.6!\n"
-                "Use the install_requires/extras_require setup() args instead."
-            )
+    def write_or_delete_file(self, what, filename, data):
+        """Write `data` to `filename` or delete if empty
 
-    def write_requirements(self):
-        dist = self.distribution
-        if not getattr(dist,'install_requires',None) and \
-           not getattr(dist,'extras_require',None): return
+        If `data` is non-empty, this routine is the same as ``write_file()``.
+        If `data` is empty but not ``None``, this is the same as calling
+        ``delete_file(filename)`.  If `data` is ``None``, then this is a no-op
+        unless `filename` exists, in which case a warning is issued about the
+        orphaned file.
+        """
+        if data:
+            self.write_file(what, filename, data)
+        elif os.path.exists(filename):
+            if data is None:
+                log.warn(
+                    "%s not set in setup(), but %s exists", what, filename
+                )
+                return
+            else:
+                self.delete_file(filename)
 
-        requires = os.path.join(self.egg_info,"requires.txt")
-        log.info("writing %s", requires)
+    def write_file(self, what, filename, data):
+        """Write `data` to `filename` (if not a dry run) after announcing it
 
+        `what` is used in a log message to identify what is being written
+        to the file.
+        """
+        log.info("writing %s to %s", what, filename)
         if not self.dry_run:
-            f = open(requires, 'wt')
-            f.write('\n'.join(yield_lines(dist.install_requires)))
-            for extra,reqs in dist.extras_require.items():
-                f.write('\n\n[%s]\n%s' % (extra, '\n'.join(yield_lines(reqs))))
+            f = open(filename, 'wb')
+            f.write(data)
             f.close()
 
+    def delete_file(self, filename):
+        """Delete `filename` (if not a dry run) after announcing it"""
+        log.info("deleting %s", filename)
+        if not self.dry_run:
+            os.unlink(filename)
+
+
+
+
+    def run(self):
+        # Make the .egg-info directory, then write PKG-INFO and requires.txt
+        self.mkpath(self.egg_info)
+        installer = self.distribution.fetch_build_egg
+        for ep in iter_entry_points('egg_info.writers'):
+            writer = ep.load(installer=installer)
+            writer(self, ep.name, os.path.join(self.egg_info,ep.name))
+
     def tagged_version(self):
         version = self.distribution.get_version()
         if self.tag_build:
@@ -132,7 +140,6 @@ class egg_info(Command):
             version += time.strftime("-%Y%m%d")
         return safe_version(version)
 
-
     def get_svn_revision(self):
         stdin, stdout = os.popen4("svn info -R"); stdin.close()
         result = stdout.read(); stdout.close()
@@ -146,60 +153,94 @@ class egg_info(Command):
         return str(max(revisions))
 
 
-    def write_toplevel_names(self):
-        pkgs = dict.fromkeys(
-            [k.split('.',1)[0]
-                for k in self.distribution.iter_distribution_names()
-            ]
+
+
+
+
+
+
+
+
+
+def write_pkg_info(cmd, basename, filename):
+    log.info("writing %s", filename)
+    if not cmd.dry_run:
+        metadata = cmd.distribution.metadata
+        metadata.version, oldver = cmd.egg_version, metadata.version
+        metadata.name, oldname   = cmd.egg_name, metadata.name
+        try:
+            # write unescaped data to PKG-INFO, so older pkg_resources
+            # can still parse it
+            metadata.write_pkg_info(cmd.egg_info)
+        finally:
+            metadata.name, metadata.version = oldname, oldver
+
+def warn_depends_obsolete(cmd, basename, filename):
+    if os.path.exists(filename):
+        log.warn(
+            "WARNING: 'depends.txt' is not used by setuptools 0.6!\n"
+            "Use the install_requires/extras_require setup() args instead."
         )
-        toplevel = os.path.join(self.egg_info, "top_level.txt")
-        log.info("writing list of top-level names to %s" % toplevel)
-        if not self.dry_run:
-            f = open(toplevel, 'wt')
-            f.write('\n'.join(pkgs))
-            f.write('\n')
-            f.close()
+
+
+def write_requirements(cmd, basename, filename):
+    dist = cmd.distribution
+    data = ['\n'.join(yield_lines(dist.install_requires or ()))]
+    for extra,reqs in (dist.extras_require or {}).items():
+        data.append('\n\n[%s]\n%s' % (extra, '\n'.join(yield_lines(reqs))))
+    cmd.write_or_delete_file("requirements", filename, ''.join(data))
+
+def write_toplevel_names(cmd, basename, filename):
+    pkgs = dict.fromkeys(
+        [k.split('.',1)[0]
+            for k in cmd.distribution.iter_distribution_names()
+        ]
+    )
+    cmd.write_file("top-level names", filename, '\n'.join(pkgs)+'\n')
+
+
+
+
+
+
+def write_arg(cmd, basename, filename):
+    argname = os.path.splitext(basename)[0]
+    value = getattr(cmd.distribution, argname, None)
+    if value is not None:
+        value = '\n'.join(value)+'\n'
+    cmd.write_or_delete_file(argname, filename, value)
+
+def write_entries(cmd, basename, filename):
+    ep = cmd.distribution.entry_points
+
+    if isinstance(ep,basestring) or ep is None:
+        data = ep
+    elif ep is not None:
+        data = []
+        for section, contents in ep.items():
+            if not isinstance(contents,basestring):
+                contents = EntryPoint.parse_list(section, contents)
+                contents = '\n'.join(map(str,contents.values()))
+            data.append('[%s]\n%s\n\n' % (section,contents))
+        data = ''.join(data)
+
+    cmd.write_or_delete_file('entry points', filename, data)
+
+
+
+
+
+
+
+
+
+
+
+
 
 
 
-    def write_or_delete_dist_arg(self, argname, filename=None):
-        value = getattr(self.distribution, argname, None)
-        filename = filename or argname+'.txt'
-        filename = os.path.join(self.egg_info,filename)
-        if value:
-            log.info("writing %s", filename)
-            if not self.dry_run:
-                f = open(filename, 'wt')
-                f.write('\n'.join(value))
-                f.write('\n')
-                f.close()
-        elif os.path.exists(filename):
-            if value is None:
-                log.warn(
-                    "%s not set in setup(), but %s exists", argname, filename
-                )
-            return
-            log.info("deleting %s", filename)
-            if not self.dry_run:
-                os.unlink(filename)
 
-    def write_entry_points(self):
-        ep = getattr(self.distribution,'entry_points',None)
-        if ep is None:
-            return
 
-        epname = os.path.join(self.egg_info,"entry_points.txt")
-        log.info("writing %s", epname)
 
-        if not self.dry_run:
-            f = open(epname, 'wt')
-            if isinstance(ep,basestring):
-                f.write(ep)
-            else:
-                for section, contents in ep.items():
-                    if not isinstance(contents,basestring):
-                        contents = EntryPoint.parse_list(section, contents)
-                        contents = '\n'.join(map(str,contents.values()))
-                    f.write('[%s]\n%s\n\n' % (section,contents))
-            f.close()