python - Why we use wrapper in decorator , when we can create decorator without wrapper? -

i reading python decorators , found them useful , have confusion tried search on google , stackoverflow couldn't found answer , 1 questions asked on stackoverflow same title question talk @wrap , question different :

so basic decorator template :

def deco(x):     def wrapper(xx):         print("before deco")         x(xx)         print("after deco")     return wrapper   def new_func(a):     print("this new function")  wow=deco(new_func) print(wow(12)) 

which result :

before deco new function after deco none 

so whenever deco return call wrapper function , not getting why using wrapper when our main goal passing new_func parameter deco function , calling parameter in deco function , if try can create same thing without wrapper function here :

def deco(x):     print("before deco")     a=1     x(a)     print("after deco")     def new_func(r):     print("this new function")   wow=deco(new_func) print(wow) 

which result :

before deco new function after deco none 

so use of wrapper in decorator ?

here's question may help. let's change new_func uses parameter it's passed. e.g.

def new_func(r):     print("new_func r:", r) 

suppose have another_func passes parameter new_func:

def another_func():     new_func(999) 

the question is, how write deco that

• another_func continues work without change and
• new_func recieves whatever value passed another_func

?