Remove a lot of dead code in SConstruct

SConstruct

@@ -27,11 +27,6 @@ CFLAGS = '-Wall -Wextra -pedantic'
 # BUILD STUFF BELOW HERE
 #
 
-import os
-import os.path
-import SCons.Errors
-
-
 if not GetOption('build_cmds'):
     def comstr(action):
         return '{:>18}: $TARGET'.format(action)
@@ -47,77 +42,25 @@ if not GetOption('build_cmds'):
     default_env['SHCXXCOMSTR'] = comstr('Building (C++)')
     default_env['SHLINKCOMSTR'] = comstr('Linking (Shared)')
 
-build_dir = Dir('#build')
-lib_dir = Dir('#lib')
-src_dir = Dir('#src')
-test_dir = Dir('#test')
+
+#test_gtest_dir = Dir('#lib/gtest')
+#test_gtest_include = test_gtest_dir.Dir('include')
+#test_env = create_env('test', [src_dir, test_dir, test_gtest_dir], {
+#    'CPPDEFINES': ['DEBUG'],
+#    'CPPPATH': [test_gtest_include],
+#    'LIBPATH': [test_gtest_dir],
+#    'CFLAGS': debug_cflags,
+#    'CXXFLAGS': debug_cflags,
+#})
 
 
-def create_env(name, src_dirs, appends=None):
-    output_dir = build_dir.Dir(name)
-    env = DefaultEnvironment().Clone()
-    env['__name'] = name
-    env['__build_dir'] = output_dir
-    env['__src_dirs'] = []
-    env['__output_dirs'] = []
-    for d in src_dirs:
-        out_dir = output_dir.Dir(d.path)
-        env['__src_dirs'].append(d)
-        env['__output_dirs'].append(out_dir)
-        env.VariantDir(out_dir, d.path, duplicate=0)
-        env.Clean('.', out_dir)
-    if appends:
-        for k, v in appends.iteritems():
-            if k.startswith('='):
-                env[k[1:]] = v
-            else:
-                env.Append(**{k: v})
-    return env
-
-
-debug_cflags = ' -O0 -g'
-debug_env = create_env('debug', [src_dir], {
-    'CPPDEFINES': ['DEBUG'],
-    'CFLAGS': debug_cflags,
-    'CXXFLAGS': debug_cflags,
-})
-
-release_cflags = ' -O2'
-release_env = create_env('release', [src_dir], {
-    'CPPDEFINES': ['RELEASE'],
-    'CFLAGS': release_cflags,
-    'CXXFLAGS': release_cflags,
-})
-
-test_gtest_dir = Dir('#lib/gtest')
-test_gtest_include = test_gtest_dir.Dir('include')
-test_env = create_env('test', [src_dir, test_dir, test_gtest_dir], {
-    'CPPDEFINES': ['DEBUG'],
-    'CPPPATH': [test_gtest_include],
-    'LIBPATH': [test_gtest_dir],
-    'CFLAGS': debug_cflags,
-    'CXXFLAGS': debug_cflags,
-})
-
-
-modes = {
-    'debug': debug_env,
-    'release': release_env,
-    'test': test_env,
-}
-
-mode = ARGUMENTS.get('MODE', None)
-build_modes = []
-if mode:
-    # If MODE=foo is specified, build only that mode.
-    build_modes.append(mode)
-else:
-    build_modes = modes.keys()
-
-for mode in build_modes:
+for mode in GetOption('modes'):
     try:
-        env = modes[mode]
+        env = MODES[mode]
     except KeyError:
         print 'Skipping invalid mode: {}'.format(mode)
-    for d in env['__output_dirs']:
-        env.SConscript(d.File('SConscript'), {'env': env})
+    library, binary = env.SConscript(SRC_DIR.File('SConscript'), {
+        'env': env
+    }, variant_dir=BUILD_DIR.Dir(env['MODE']).Dir('src'), duplicate=0)
+    env.Alias('lib', library)
+    env.Alias('bin', binary)