N = 1 or val in python-CodePudding

In lua I can express this:

function f(arg)
   N = arg or 0
   print(N) 
end 

F()
F(5)

Output: 
--> 0
--> 5

Is there a way to do that in python... instead of:

arg = None
If arg: 
   N = arg
else: 
   N = 0

--> n = 0 
-- set arg to 5 
--> n = 5

Just curious, I like the Lua 1 line implementation of that. The other one is kinda jank to me.

CodePudding user response：

Here is my real issue:

def f(number,*args):
  if args:
    N = args[0]
  else:
    N= 0 

 .... so on and so on

If I try:

def f(number,*args):
   N = args[0] or 0

This returns out of range error.

For context: I was just playing around with recursion. This function on first run doesn't get passed args. It then gets passed args after the recursion.

CodePudding user response：

you can use or the other way around like this:

def f(arg=None):
    N = arg or 0
    print(N)

f()  # 0
f(5)  # 5

The second option is chosen whenever arg is False or None. https://docs.python.org/3/library/stdtypes.html#boolean-operations-and-or-not

EDIT: You are looking for next

N = next(iter(args), 0)

args is a tuple of all the additional parameters passed to your function. You can use next in combination with iter to iterate over those parameters and select the next/first, if it exists. If not, a default value gets assigned to N (in this case 0). Its similar to N = args[0] if len(args) > 0 else 0 but without the check. Some more explanation is here for example.