Add support for package data.

This is basically the support for package data from Phillip Eby's
setuptools package.  I've changed it only to fit it into the core
implementation rather than to live in subclasses, and added
documentation.

Lib/distutils/command/build_py.py

@@ -37,6 +37,7 @@ class build_py (Command):
         self.build_lib = None
         self.py_modules = None
         self.package = None
+        self.package_data = None
         self.package_dir = None
         self.compile = 0
         self.optimize = 0
@@ -51,6 +52,8 @@ class build_py (Command):
         # options -- list of packages and list of modules.
         self.packages = self.distribution.packages
         self.py_modules = self.distribution.py_modules
+        self.package_data = self.distribution.package_data
+        self.data_files = self.get_data_files()
         self.package_dir = {}
         if self.distribution.package_dir:
             for name, path in self.distribution.package_dir.items():
@@ -92,11 +95,53 @@ class build_py (Command):
             self.build_modules()
         if self.packages:
             self.build_packages()
+            self.build_package_data()
 
         self.byte_compile(self.get_outputs(include_bytecode=0))
 
     # run ()
 
+    def get_data_files (self):
+        """Generate list of '(package,src_dir,build_dir,filenames)' tuples"""
+        data = []
+        for package in self.packages:
+            # Locate package source directory
+            src_dir = self.get_package_dir(package)
+
+            # Compute package build directory
+            build_dir = os.path.join(*([self.build_lib] + package.split('.')))
+
+            # Length of path to strip from found files
+            plen = len(src_dir)+1
+
+            # Strip directory from globbed filenames
+            filenames = [
+                file[plen:] for file in self.find_data_files(package, src_dir)
+                ]
+            data.append((package, src_dir, build_dir, filenames))
+        return data
+
+    def find_data_files (self, package, src_dir):
+        """Return filenames for package's data files in 'src_dir'"""
+        globs = (self.package_data.get('', [])
+                 + self.package_data.get(package, []))
+        files = []
+        for pattern in globs:
+            # Each pattern has to be converted to a platform-specific path
+            filelist = glob(os.path.join(src_dir, convert_path(pattern)))
+            # Files that match more than one pattern are only added once
+            files.extend([fn for fn in filelist if fn not in files])
+        return files
+
+    def build_package_data (self):
+        """Copy data files into build directory"""
+        lastdir = None
+        for package, src_dir, build_dir, filenames in self.data_files:
+            for filename in filenames:
+                target = os.path.join(build_dir, filename)
+                self.mkpath(os.path.dirname(target))
+                self.copy_file(os.path.join(src_dir, filename), target,
+                               preserve_mode=False)
 
     def get_package_dir (self, package):
         """Return the directory, relative to the top of the source
@@ -304,6 +349,12 @@ class build_py (Command):
                 if self.optimize > 0:
                     outputs.append(filename + "o")
 
+        outputs += [
+            os.path.join(build_dir, filename)
+            for package, src_dir, build_dir, filenames in self.data_files
+            for filename in filenames
+            ]
+
         return outputs