CODEWITHSUNDEEP
python
chkiss
chkiss

Reputation: 43

"or" boolean in an inline "if" statement

I have a program that begins by parsing several arguments, one of which is a "verbose" flag. However, I also have a "simulate" flag, which I would like to automatically flip the verbose flag to "True" if it is on.

Right now I have this working: 

if args.verbose or simulate:  
    verbose = True

How can I get this onto one line? I was expecting to be able to do something like:

verbose = True if args.verbose or simulate

or like:

verbose = True if (args.verbose or simulate)

While searching here, I found a solution that fits on one line:

verbose = (False, True)[args.verbose or simulate]

However, I find that solution to be much less readable than the others that I was hoping would work. Is this possible, and I'm just missing something? Or is it not possible to use an "or" between two checks for "True" like this in one line?

Upvotes: 2

Views: 646

Answers (2)

willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 477160

A functionally equivalent expression would be:

verbose = True if args.verbose or simulate else verbose

since it is possible that verbose is already True, or something else (a number, a list, a dictionary, etc.)

Furthermore if we are not sure arg.verbose and simulate are booleans, we can not use:

verbose = arg.verbose or simulate

since if for example simulate is [1], then we get:

>>> False or [1]
[1]

We can however convert this expression to a boolean, like:

verbose = bool(arg.verbose or simulate) or verbose

here in case the condition is False, we assign verbose back to verbose (since again it is possible that verbose has been set to something other than False).

If however both simulate and verbose are known to be booleans, we can use:

verbose = arg.verbose or simulate or verbose

In case it is known that verbose has been set to False initially:

verbose = arg.verbose or simulate

is sufficient. In that case we can skip the previous initialization of verbose (given it is not used between the initialization and setting it here).

Upvotes: 1

John Kugelman
John Kugelman

Reputation: 361849

The problem isn't with or, it's that you need an else clause to specify what the value should be if the if statement fails. Otherwise, what is getting assigned if the condition is false?

verbose = True if args.verbose or simulate else False

There's no need for the if at all, though. It's even simpler if you just assign the result of the test to verbose directly:

verbose = args.verbose or simulate

Upvotes: 5

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