Myujth

I am currently working on a plotting command for custom objects in C++. I am using Xcode v10.1.

I import my own commands with command script import test.py where there is a function as following:

import lldb

def test_function(debugger, command, result, dict):
 obj = lldb.frame.FindVariable("custom_object")
 print(obj)

def __lldb_init_module (debugger, dict):
 debugger.HandleCommand('command script add -f test.test_function test')

Where custom object is an object I want to use in the Python script.

If I have just opened the debugger I get the error:

obj = lldb.frame.FindVariable("custom_object")
AttributeError: 'NoneType' object has no attribute 'FindVariable'

However when I open the embedded Python interpreter in Xcode directly and execute the same line of code as above I get no error.

If I now execute my custom command again it executes successfully for all objects in the same scope of the debugger.

lldb.frame is not defined in lldb python based commands - that's why it is NoneType. lldb.process, thread,frame are just for convenience in the interactive script interpreter. But it wouldn't make sense for a command - which might get run in a stop hook, a breakpoint command, etc. to rely on some global state for its process & thread. After all, you could have two threads hitting the same breakpoint at the same time. So there isn't a unique "lldb.thread".

It's better to use the version of the command function which takes a SBExecutionContext as the third argument (this is described in http://lldb.llvm.org/python-reference.html) and get the thread and frame from that argument.