tracing.py

import inspect
import sys
import functools


def trace(f):
    signature = inspect.signature(f)
    indent = ''
    @functools.wraps(f)
    def decorated(*a, **ka):
        nonlocal indent
        bound = signature.bind(*a, **ka)
        #bound.apply_defaults()
        bound_repr = ', '.join(
            f'{name}={value!r}' for name, value in bound.arguments.items()
        )
        print(f'{indent}Entering {f.__name__}({bound_repr})')
        indent += '  '
        result = f(*a, **ka)
        indent = indent[:-2]
        print(f'{indent}Exiting  {f.__name__}({bound_repr}) = {result}')
        return result
    return decorated


#trace
def fib(n, foo=1):
    if n <= 1:
        return 1
    a = 3
    return fib(n-1) + fib(n-2)

indent = ''
def tracefunc(frame, event, arg):
    global indent
    if event == 'call':
        print(f'{indent}Entering {frame.f_code.co_name}({frame.f_locals})')
        indent += '  '
    if event == 'return':
        indent = indent[:-2]
        print(f'{indent}Exiting  {frame.f_code.co_name}(...) = {arg}')
    if event == 'line':
        print(f'{indent}{frame.f_lineno} ({frame.f_code.co_filename})')
    return tracefunc

sys.settrace(tracefunc)

for i in range(10):
    print(i, fib(i))