#!/usr/bin/env python3

from sys import settracestate, gettracestate
from dis import disassemble, get_instructions


def gtrace(g_frame, g_event, g_arg):
  code = g_frame.f_code
  name = code.co_name
  insts = tuple(get_instructions(code))
  print(f'! gtrace: {g_event}: {name}')
  disassemble(code)

  if g_event != 'call': return None

  prev_off = -1

  def ltrace(frame, event, arg):
    nonlocal prev_off
    assert frame.f_code == code
    line = frame.f_lineno
    offset = frame.f_lasti
    index = offset // 2 # as of python3.6, all instructions are 2 bytes.
    inst = insts[index]
    argrepr = inst.argrepr and ' ' + inst.argrepr
    print(f'!   ltrace: {event[:4]}: {name}:{line}: {prev_off} -> {offset}: 0x{inst.opcode:02x} {inst.opname}{argrepr}')
    prev_off = offset
    return ltrace

  return ltrace


def example():
  try:
    f()
  except ZeroDivisionError as e:
    print('example exception:', e)

def f():
  print("f")
  g()
  1//0 # test raise tracing.

def g():
  print("g")

settracestate(gtrace, trace_instructions=True)
example()

print('\n---- test gettracestate ----\n')
print('sys.gettracestate:', gettracestate())
settracestate(None)
print('sys.gettracestate:', gettracestate())