[lldb/Commands] Fix outdated `breakpoint command add` help string

[kastiglione]

Summary

Update the some examples in the help string for breakpoint command add.

Python breakpoint commands have different output than what's shown in the help string.

Notes:

• Removed an example containing an inner function, as it seems more about a Python technique than about command script add
• Updated print x to print(x) to be python 2/3 agnostic

[kastiglione]

lldb/source/Commands/CommandObjectBreakpointCommand.cpp

174–181

Does anyone think this should be kept?

[jingham]

LGTM, if you want to remove the last example, I say go ahead. If you want to dig in more, then we should go through another review for the useful example.

lldb/source/Commands/CommandObjectBreakpointCommand.cpp

174–181

It is potentially interesting that you can put other code in this definition, so long as there's only one function defined. Maybe you could use that to initialize something you were planning to log to (open a file or something?) But if that's what we are showing people, we should actually describe what it's legit to do other than define a function in this input editor.

As it is, it's overly mysterious and not very helpful. And the example is unmotivated so it's just confusing...

If you feel like digging into what else can go here, and come up with a motivated example that's actually useful, I think that would be handy. But otherwise, I'm fine with deleting the last example.

[kastiglione]

lldb/source/Commands/CommandObjectBreakpointCommand.cpp

174–181

I see, yes, though I don't have any such examples ready and waiting. I haven't found myself turning to multiline python expressions that contain functions. Can you check my understanding, in this example breakpoint_output is a named lambda, and you're saying it would be nice to have an example that uses a named lambda? If so, I don't think I have a good example.

lldb/source/Commands/CommandObjectBreakpointCommand.cpp

 variables requires explicit scoping using the 'global' keyword.  Be sure to use correct \
 Python syntax, including indentation, when entering Python breakpoint commands."
         R"(
 
 Example Python one-line breakpoint command:
 
 (lldb) breakpoint command add -s python 1
 Enter your Python command(s). Type 'DONE' to end.
-> print "Hit this breakpoint!"
-> DONE
+def function (frame, bp_loc, internal_dict):
+    """frame: the lldb.SBFrame for the location at which you stopped
+       bp_loc: an lldb.SBBreakpointLocation for the breakpoint location information
+       internal_dict: an LLDB support object not to be used"""
+    print("Hit this breakpoint!")
+    DONE
 
 As a convenience, this also works for a short Python one-liner:
 
-(lldb) breakpoint command add -s python 1 -o 'import time; print time.asctime()'
+(lldb) breakpoint command add -s python 1 -o 'import time; print(time.asctime())'
 (lldb) run
 Launching '.../a.out'  (x86_64)
 (lldb) Fri Sep 10 12:17:45 2010
 Process 21778 Stopped
 * thread #1: tid = 0x2e03, 0x0000000100000de8 a.out`c + 7 at main.c:39, stop reason = breakpoint 1.1, queue = com.apple.main-thread
   36
   37    int c(int val)
   38    {
   39 ->      return val + 3;
   40    }
   41
   42    int main (int argc, char const *argv[])
 
 Example multiple line Python breakpoint command:
 
 (lldb) breakpoint command add -s p 1
 Enter your Python command(s). Type 'DONE' to end.
-> global bp_count
-> bp_count = bp_count + 1
-> print "Hit this breakpoint " + repr(bp_count) + " times!"
-> DONE
-
-Example multiple line Python breakpoint command, using function definition:
-
-(lldb) breakpoint command add -s python 1
-Enter your Python command(s). Type 'DONE' to end.
-> def breakpoint_output (bp_no):
->     out_string = "Hit breakpoint number " + repr (bp_no)
->     print out_string
->     return True
-> breakpoint_output (1)
-> DONE
+def function (frame, bp_loc, internal_dict):
+    """frame: the lldb.SBFrame for the location at which you stopped
+       bp_loc: an lldb.SBBreakpointLocation for the breakpoint location information
+       internal_dict: an LLDB support object not to be used"""
+    global bp_count
+    bp_count = bp_count + 1
+    print("Hit this breakpoint " + repr(bp_count) + " times!")
+    DONE
 
 )"
         "In this case, since there is a reference to a global variable, \
 'bp_count', you will also need to make sure 'bp_count' exists and is \
 initialized:"
         R"(
 
 (lldb) script