Modernize the example cmdtemplate.py.

This version relies on a newer and more convenient way
to use a class to implement a command.  It has been in place
since early 2015, so it should be pretty safe to use.

1 files changed, 95 insertions, 85 deletions

diff --git a/lldb/examples/python/cmdtemplate.py b/lldb/examples/python/cmdtemplate.py
index dfe3e6fa52b..4d506b91aaf 100644
--- a/lldb/examples/python/cmdtemplate.py
+++ b/lldb/examples/python/cmdtemplate.py
@@ -14,99 +14,109 @@ import commands
 import optparse
 import shlex
 
+class FrameStatCommand:
+    def create_options(self):
 
-def create_framestats_options():
-    usage = "usage: %prog [options]"
-    description = '''This command is meant to be an example of how to make an LLDB command that
+        usage = "usage: %prog [options]"
+        description = '''This command is meant to be an example of how to make an LLDB command that
 does something useful, follows best practices, and exploits the SB API.
 Specifically, this command computes the aggregate and average size of the variables in the current frame
 and allows you to tweak exactly which variables are to be accounted in the computation.
 '''
-    parser = optparse.OptionParser(
-        description=description,
-        prog='framestats',
-        usage=usage)
-    parser.add_option(
-        '-i',
-        '--in-scope',
-        action='store_true',
-        dest='inscope',
-        help='in_scope_only = True',
-        default=False)
-    parser.add_option(
-        '-a',
-        '--arguments',
-        action='store_true',
-        dest='arguments',
-        help='arguments = True',
-        default=False)
-    parser.add_option(
-        '-l',
-        '--locals',
-        action='store_true',
-        dest='locals',
-        help='locals = True',
-        default=False)
-    parser.add_option(
-        '-s',
-        '--statics',
-        action='store_true',
-        dest='statics',
-        help='statics = True',
-        default=False)
-    return parser
-
-
-def the_framestats_command(debugger, command, result, dict):
-    # Use the Shell Lexer to properly parse up command options just like a
-    # shell would
-    command_args = shlex.split(command)
-    parser = create_framestats_options()
-    try:
-        (options, args) = parser.parse_args(command_args)
-    except:
-        # if you don't handle exceptions, passing an incorrect argument to the OptionParser will cause LLDB to exit
-        # (courtesy of OptParse dealing with argument errors by throwing SystemExit)
-        result.SetError("option parsing failed")
-        return
-
-    # in a command - the lldb.* convenience variables are not to be used
-    # and their values (if any) are undefined
-    # this is the best practice to access those objects from within a command
-    target = debugger.GetSelectedTarget()
-    process = target.GetProcess()
-    thread = process.GetSelectedThread()
-    frame = thread.GetSelectedFrame()
-    if not frame.IsValid():
-        return "no frame here"
-    # from now on, replace lldb.<thing>.whatever with <thing>.whatever
-    variables_list = frame.GetVariables(
-        options.arguments,
-        options.locals,
-        options.statics,
-        options.inscope)
-    variables_count = variables_list.GetSize()
-    if variables_count == 0:
-        print >> result, "no variables here"
-        return
-    total_size = 0
-    for i in range(0, variables_count):
-        variable = variables_list.GetValueAtIndex(i)
-        variable_type = variable.GetType()
-        total_size = total_size + variable_type.GetByteSize()
-    average_size = float(total_size) / variables_count
-    print >>result, "Your frame has %d variables. Their total size is %d bytes. The average size is %f bytes" % (
-        variables_count, total_size, average_size)
-    # not returning anything is akin to returning success
+
+        # Pass add_help_option = False, since this keeps the command in line with lldb commands, 
+        # and we wire up "help command" to work by providing the long & short help methods below.
+        self.parser = optparse.OptionParser(
+            description = description,
+            prog = 'framestats',
+            usage = usage,
+            add_help_option = False)
+
+        self.parser.add_option(
+            '-i',
+            '--in-scope',
+            action = 'store_true',
+            dest = 'inscope',
+            help = 'in_scope_only = True',
+            default = True)
+
+        self.parser.add_option(
+            '-a',
+            '--arguments',
+            action = 'store_true',
+            dest = 'arguments',
+            help = 'arguments = True',
+            default = True)
+
+        self.parser.add_option(
+            '-l',
+            '--locals',
+            action = 'store_true',
+            dest = 'locals',
+            help = 'locals = True',
+            default = True)
+
+        self.parser.add_option(
+            '-s',
+            '--statics',
+            action = 'store_true',
+            dest = 'statics',
+            help = 'statics = True',
+            default = True)
+ 
+    def get_short_help(self):
+        return "Example command for use in debugging"
+
+    def get_long_help(self):
+        return self.help_string
+
+    def __init__(self, debugger, unused):
+        self.create_options()
+        self.help_string = self.parser.format_help()
+
+    def __call__(self, debugger, command, exe_ctx, result):
+        # Use the Shell Lexer to properly parse up command options just like a
+        # shell would
+        command_args = shlex.split(command)
+        
+        try:
+            (options, args) = self.parser.parse_args(command_args)
+        except:
+            # if you don't handle exceptions, passing an incorrect argument to the OptionParser will cause LLDB to exit
+            # (courtesy of OptParse dealing with argument errors by throwing SystemExit)
+            result.SetError("option parsing failed")
+            return
+
+        # Always get program state from the SBExecutionContext passed in as exe_ctx
+        frame = exe_ctx.GetFrame()
+        if not frame.IsValid():
+            result.SetError("invalid frame")
+            return
+
+        variables_list = frame.GetVariables(
+            options.arguments,
+            options.locals,
+            options.statics,
+            options.inscope)
+        variables_count = variables_list.GetSize()
+        if variables_count == 0:
+            print >> result, "no variables here"
+            return
+        total_size = 0
+        for i in range(0, variables_count):
+            variable = variables_list.GetValueAtIndex(i)
+            variable_type = variable.GetType()
+            total_size = total_size + variable_type.GetByteSize()
+            average_size = float(total_size) / variables_count
+            print >>result, "Your frame has %d variables. Their total size is %d bytes. The average size is %f bytes" % (
+                variables_count, total_size, average_size)
+         # not returning anything is akin to returning success
 
 
 def __lldb_init_module(debugger, dict):
     # This initializer is being run from LLDB in the embedded command interpreter
-    # Make the options so we can generate the help text for the new LLDB
-    # command line command prior to registering it with LLDB below
-    parser = create_framestats_options()
-    the_framestats_command.__doc__ = parser.format_help()
+
     # Add any commands contained in this module to LLDB
     debugger.HandleCommand(
-        'command script add -f cmdtemplate.the_framestats_command framestats')
-    print 'The "framestats" command has been installed, type "help framestats" or "framestats --help" for detailed help.'
+        'command script add -c cmdtemplate.FrameStatCommand framestats')
+    print 'The "framestats" command has been installed, type "help framestats" for detailed help.'