With and without parameters decorator merge

def log(text=None):
      def decorator(func):
            @functools.wraps(func)
            def wrapper(*args,**kw):
                  if callable(text):
                        print ('call %s():'%func.__name__)
                  else:
                        print ('%s %s():'%(text,func.__name__))
                  return func(*args,**kw)
            return wrapper
      return decorator(text) if callable(text) else decorator

@log('excute') #decorator_1
def test4(i,j):
      return i*j

@log    #decorator_2
def test5(m,n):
      return m+n

1, decorator_1 execution process:

    test4 = log('excute')(test4)

        Step 1: Execute log('execute') execute is incallable return decorator

        Step 2: Execute decorator(test4) to return wrapper, ie test4 = wrapper

        Step 3: When calling test4, call wrapper to print print ('%s %s():'%(text,func.__name__)) and return to execute the original function test4

2.decorator_2 execution process:

    test5 = log (test5)

        Step 1: Execute log(test5), test5 is callable return decorator(test5)

        Step 2: Execute decorator(test5), return wrapper, ie test5 = wrapper

        Step 3: When calling test5, call wrapper to print print ('call %s():'%func.__name__) and return to execute the original function test5