Implement -m command line flag to run a module by name

docs/language/cli.rst

@@ -23,6 +23,16 @@ Command line options
 
    Execute the Hy code in *command*, then stay in REPL.
 
+.. cmdoption:: -m <module>
+
+   Execute the Hy code in *module*, including ``defmain`` if defined.
+
+   The :option:`-m` flag terminates the options list so that
+   all arguments after the *module* name are passed to the module in
+   ``sys.argv``.
+
+   .. versionadded:: 0.10.2
+
 .. cmdoption:: --spy
 
    Print equivalent Python code before executing. For example::

hy/cmdline.py

@@ -188,6 +188,18 @@ def run_command(source):
     return 0
 
 
+def run_module(mod_name):
+    from hy.importer import MetaImporter
+    pth = MetaImporter().find_on_path(mod_name)
+    if pth is not None:
+        sys.argv = [pth] + sys.argv
+        return run_file(pth)
+
+    sys.stderr.write("{0}: module '{1}' not found.\n".format(hy.__appname__,
+                                                             mod_name))
+    return 1
+
+
 def run_file(filename):
     from hy.importer import import_file_to_module
     try:
@@ -230,9 +242,10 @@ def run_icommand(source, spy=False):
     return run_repl(hr)
 
 
-USAGE = "%(prog)s [-h | -i cmd | -c cmd | file | -] [arg] ..."
+USAGE = "%(prog)s [-h | -i cmd | -c cmd | -m module | file | -] [arg] ..."
 VERSION = "%(prog)s " + hy.__version__
 EPILOG = """  file         program read from script
+  module       module to execute as main
   -            program read from stdin
   [arg] ...    arguments passed to program in sys.argv[1:]
 """
@@ -246,6 +259,8 @@ def cmdline_handler(scriptname, argv):
         epilog=EPILOG)
     parser.add_argument("-c", dest="command",
                         help="program passed in as a string")
+    parser.add_argument("-m", dest="mod",
+                        help="module to run, passed in as a string")
     parser.add_argument(
         "-i", dest="icommand",
         help="program passed in as a string, then stay in REPL")
@@ -265,6 +280,16 @@ def cmdline_handler(scriptname, argv):
     # mimics Python sys.executable
     hy.executable = argv[0]
 
+    # need to split the args if using "-m"
+    # all args after the MOD are sent to the module
+    # in sys.argv
+    module_args = []
+    if "-m" in argv:
+        mloc = argv.index("-m")
+        if len(argv) > mloc+2:
+            module_args = argv[mloc+2:]
+            argv = argv[:mloc+2]
+
     options = parser.parse_args(argv[1:])
 
     if options.show_tracebacks:
@@ -272,12 +297,16 @@ def cmdline_handler(scriptname, argv):
         SIMPLE_TRACEBACKS = False
 
     # reset sys.argv like Python
-    sys.argv = options.args or [""]
+    sys.argv = options.args + module_args or [""]
 
     if options.command:
         # User did "hy -c ..."
         return run_command(options.command)
 
+    if options.mod:
+        # User did "hy -m ..."
+        return run_module(options.mod)
+
     if options.icommand:
         # User did "hy -i ..."
         return run_icommand(options.icommand, spy=options.spy)

tests/test_bin.py

@@ -173,3 +173,27 @@ def test_bin_hy_no_main():
     ret = run_cmd("hy tests/resources/bin/nomain.hy")
     assert ret[0] == 0
     assert "This Should Still Work" in ret[1]
+
+
+def test_bin_hy_module_main():
+    ret = run_cmd("hy -m tests.resources.bin.main")
+    assert ret[0] == 0
+    assert "Hello World" in ret[1]
+
+
+def test_bin_hy_module_main_args():
+    ret = run_cmd("hy -m tests.resources.bin.main test 123")
+    assert ret[0] == 0
+    assert "test" in ret[1]
+    assert "123" in ret[1]
+
+
+def test_bin_hy_module_main_exitvalue():
+    ret = run_cmd("hy -m tests.resources.bin.main exit1")
+    assert ret[0] == 1
+
+
+def test_bin_hy_module_no_main():
+    ret = run_cmd("hy -m tests.resources.bin.nomain")
+    assert ret[0] == 0
+    assert "This Should Still Work" in ret[1]