From ea680f204fb0e48789710c22c8f597a9bf01bc16 Mon Sep 17 00:00:00 2001
From: Richard Ipsum <richard.ipsum@codethink.co.uk>
Date: Fri, 17 Oct 2014 12:02:57 +0100
Subject: Add --list-dependencies option

---
 pip/commands/install.py | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/pip/commands/install.py b/pip/commands/install.py
index cbf22a086..4589130cb 100644
--- a/pip/commands/install.py
+++ b/pip/commands/install.py
@@ -160,6 +160,13 @@ class InstallCommand(Command):
 
         cmd_opts.add_option(cmdoptions.no_clean.make())
 
+        cmd_opts.add_option(
+            '--list-dependencies',
+            dest="list_dependencies",
+            metavar="file",
+            default=None,
+            help="Don't install anything, write all dependencies into <file>")
+
         index_opts = cmdoptions.make_option_group(cmdoptions.index_group, self.parser)
 
         self.parser.insert_option_group(0, index_opts)
@@ -183,6 +190,14 @@ class InstallCommand(Command):
                              session=session,
                             )
 
+    def write_dependencies_to_file(self, path, requirements):
+        def strspecs(specs):
+            return ''.join(['%s%s,' % (op, ver) for (op, ver) in specs]).rstrip(',')
+
+        with open(path, 'w') as f:
+            for req in requirements.values():
+                f.write('%s%s\n' % (req.name, strspecs(req.req.specs)))
+
     def run(self, options, args):
 
         if (
@@ -252,6 +267,7 @@ class InstallCommand(Command):
             session=session,
             pycompile=options.compile,
         )
+
         for name in args:
             requirement_set.add_requirement(
                 InstallRequirement.from_line(name, None))
@@ -274,11 +290,17 @@ class InstallCommand(Command):
             return
 
         try:
+            # Obtain requirement set
             if not options.no_download:
                 requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
             else:
                 requirement_set.locate_files()
 
+            if options.list_dependencies:
+                self.write_dependencies_to_file(options.list_dependencies,
+                                                requirement_set.requirements)
+                return
+
             if not options.no_install and not self.bundle:
                 requirement_set.install(install_options, global_options, root=options.root_path)
                 installed = ' '.join([req.name for req in
-- 
cgit v1.2.1