[lldb-dev] executing a c++ function from lldb python script

[Niels Bogaards]

Thanks a lot, works like a charm! 

Niels

> Yes, "lldb.target", "lldb.process", "lldb.thread" and "lldb.frame" are no longer set as they are global values that can be changed by code that re-enters python. We are need people to not use them anymore except when using the "script" command.
> 
> So to fix this you will want to grab your frame from the debugger object that is passed in:
> 
>    target =  debugger.GetSelectedTarget()
>    process = target.GetProcess()
>    thread = process.GetSelectedThread()
>    frame = thread.GetSelectedFrame()
> 
> Then use "frame" instead of "lldb.frame" when calling EvaluateExpression. Also instead of using magic values, you can use the enums for the 2nd param to EvaluateExpression:
> 
>    res = frame.EvaluateExpression(ecom, lldb.eDynamicCanRunTarget)
> 
> Then be sure to set your error correctly instead of initializing it with a default constructed value:
> 
>    error = res.GetError()
> 
> You might also want to make sure your process is stopped before trying to run the expression:
> 
> 
>    if process.GetState() == eStateStopped:
>        # Evaluate expression
>    else:
>        # print error
> 
> On Jan 7, 2014, at 5:22 AM, Niels Bogaards <niels at elephantcandy.com> wrote:
> 
>> Hi,
>> 
>> I made a script for lldb last year that allowed me to plot a custom object as a curve from Xcode’s lldb prompt. Worked very well for a year, but no more. Has anything changed in the EvaluateExpression syntax? Are there linker options I need to activate in my target c++ program?
>> 
>> Thanks for any help,
>> 
>> Niels
>> 
>> 
>> Here's the script, it outputs: 
>> 
>> - DEBUG - res is No value
>> - DEBUG - fname is No value
>> - DEBUG - error is error: <NULL>
>> 
>> 
>> import lldb
>> import commands
>> import optparse
>> import shlex
>> import logging
>> 
>> def plot(debugger, command, result, dict):
>> 	logging.basicConfig(level=logging.DEBUG, format='%(asctime)s - %(levelname)s - %(message)s')
>> 	command_args = shlex.split(command)
>> 	usage = "usage: %prog objectName "
>> 	description=‘''plot'''
>> 	parser = optparse.OptionParser(description=description, prog='plot',usage=usage)
>> 	
>> 	try:
>> 		(options, args) = parser.parse_args(command_args)
>> 	except:
>> 		print '"plot" exception'
>> 		return
>> 	la = len(args)
>> 	print 'len args = %d' % la
>> 	if len(args) == 1:
>> 		ecom = “MyNamespace::MyClass::MyStaticPlotFunction(%s)" % args[0]
>> 		res = lldb.frame.EvaluateExpression(ecom, 1)
>> 		fname = lldb.frame.EvaluateExpression("MyNamespace::MyClass::GetStaticPlotFileName()")
>> 		error = lldb.SBError()
>> 		logging.debug("res is %s", res);
>> 		logging.debug("fname is %s", fname);
>> 		logging.debug("error is %s", error);
>> 
>> if __name__ == '__main__':
>>    # This script is being run from the command line, create a debugger in case we are
>>    # going to use any debugger functions in our function.
>>    lldb.debugger = lldb.SBDebugger.Create()
>>    plot (sys.argv)
>> 
>> def __lldb_init_module (debugger, dict):
>>    # This initializer is being run from LLDB in the embedded command interpreter
>>    # Add any commands contained in this module to LLDB
>>    debugger.HandleCommand('command script add -f plot.plot plot')
>>    print '"plot" command installed, type "plot --help" for detailed help'
>> 
>> _______________________________________________
>> lldb-dev mailing list
>> lldb-dev at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
>