Fix and simplify lldb.command decorator

Summary:
This change fixes one issue with `lldb.command`, and also reduces the implementation.

The fix: a command function's docstring was not shown when running `help <command_name>`. This is because the docstring attached the source function is not propagated to the decorated function (`f.__call__`). By returning the original function, the docstring will be properly displayed by `help`.

Also with this change, the command name is assumed to be the function's name, but can still be explicitly defined as previously.

Additionally, the implementation was updated to:

* Remove inner class
* Remove use of `inspect` module
* Remove `*args` and `**kwargs`

Reviewers: clayborg

Reviewed By: clayborg

Subscribers: keith, xiaobai, lldb-commits

Differential Revision: https://reviews.llvm.org/D48658

llvm-svn: 336287

4 files changed, 53 insertions, 21 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/command_script/TestCommandScript.py b/lldb/packages/Python/lldbsuite/test/functionalities/command_script/TestCommandScript.py
index 103189e9dd5..1698c0d0c35 100644
--- a/lldb/packages/Python/lldbsuite/test/functionalities/command_script/TestCommandScript.py
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/command_script/TestCommandScript.py
@@ -49,6 +49,7 @@ class CmdPythonTestCase(TestBase):
             self.runCmd('command script delete tell_curr', check=False)
             self.runCmd('command script delete bug11569', check=False)
             self.runCmd('command script delete takes_exe_ctx', check=False)
+            self.runCmd('command script delete decorated', check=False)
 
         # Execute the cleanup function during test case tear down.
         self.addTearDownHook(cleanup)
@@ -67,13 +68,19 @@ class CmdPythonTestCase(TestBase):
                     substrs=['Just a docstring for welcome_impl',
                              'A command that says hello to LLDB users'])
 
+        decorated_commands = ["decorated" + str(n) for n in range(1, 5)]
+        for name in decorated_commands:
+            self.expect(name, substrs=["hello from " + name])
+            self.expect("help " + name,
+                        substrs=["Python command defined by @lldb.command"])
+
         self.expect("help",
                     substrs=['For more information run',
-                             'welcome'])
+                             'welcome'] + decorated_commands)
 
         self.expect("help -a",
                     substrs=['For more information run',
-                             'welcome'])
+                             'welcome'] + decorated_commands)
 
         self.expect("help -u", matching=False,
                     substrs=['For more information run'])
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/command_script/decorated.py b/lldb/packages/Python/lldbsuite/test/functionalities/command_script/decorated.py
new file mode 100644
index 00000000000..f9707a5706a
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/command_script/decorated.py
@@ -0,0 +1,35 @@
+from __future__ import print_function
+
+import lldb
+
+
+@lldb.command()
+def decorated1(debugger, args, exe_ctx, result, dict):
+    """
+    Python command defined by @lldb.command
+    """
+    print("hello from decorated1", file=result)
+
+
+@lldb.command(doc="Python command defined by @lldb.command")
+def decorated2(debugger, args, exe_ctx, result, dict):
+    """
+    This docstring is overridden.
+    """
+    print("hello from decorated2", file=result)
+
+
+@lldb.command()
+def decorated3(debugger, args, result, dict):
+    """
+    Python command defined by @lldb.command
+    """
+    print("hello from decorated3", file=result)
+
+
+@lldb.command("decorated4")
+def _decorated4(debugger, args, exe_ctx, result, dict):
+    """
+    Python command defined by @lldb.command
+    """
+    print("hello from decorated4", file=result)
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/command_script/py_import b/lldb/packages/Python/lldbsuite/test/functionalities/command_script/py_import
index 169daacc1a8..6c1f7b8185f 100644
--- a/lldb/packages/Python/lldbsuite/test/functionalities/command_script/py_import
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/command_script/py_import
@@ -10,3 +10,4 @@ command script add tell_sync --function welcome.check_for_synchro --synchronicit
 command script add tell_async --function welcome.check_for_synchro --synchronicity async
 command script add tell_curr --function welcome.check_for_synchro --synchronicity curr
 command script add takes_exe_ctx --function welcome.takes_exe_ctx
+command script import decorated.py
diff --git a/lldb/scripts/Python/python-extensions.swig b/lldb/scripts/Python/python-extensions.swig
index d79917b9215..5543bee95d4 100644
--- a/lldb/scripts/Python/python-extensions.swig
+++ b/lldb/scripts/Python/python-extensions.swig
@@ -839,29 +839,18 @@
 
 %pythoncode %{
 
-def command(*args, **kwargs):
+def command(command_name=None, doc=None):
     import lldb
-    import inspect
     """A decorator function that registers an LLDB command line
         command that is bound to the function it is attached to."""
-    class obj(object):
-        """The object that tracks adding the command to LLDB one time and handles
-            calling the function on subsequent calls."""
-        def __init__(self, function, command_name, doc = None):
-            if doc:
-                function.__doc__ = doc
-            command = "command script add -f %s.%s %s" % (function.__module__, function.__name__, command_name)
-            lldb.debugger.HandleCommand(command)
-            self.function = function
-        def __call__(self, debugger, command, exe_ctx, result, dict):
-            if len(inspect.getargspec(self.function).args) == 5:
-                self.function(debugger, command, exe_ctx, result, dict)
-            else:
-                self.function(debugger, command, result, dict)
     def callable(function):
-        """Creates a callable object that gets used."""
-        f = obj(function, *args, **kwargs)
-        return f.__call__
+        """Registers an lldb command for the decorated function."""
+        command = "command script add -f %s.%s %s" % (function.__module__, function.__name__, command_name or function.__name__)
+        lldb.debugger.HandleCommand(command)
+        if doc:
+            function.__doc__ = doc
+        return function
+
     return callable
 
 class declaration(object):