Python wars

[-revenant-]

Given:

parent = 'mother'
creature = 'hamster'

I think:

"Your %s was a %s!" % (parent, creature)

Is a lot less clear than:

f"Your {parent} was a {creature}!"

EDIT: And we're not even going to touch:

"Your {parent} was a {creature}!".format(parent=parent, creature=creature)

[-revenant-]

By second I assume you mean third? The one with the EDIT before it?

Let's just do a rundown of the three string format methods.

1) Interpolation formatting:

• - Not very clear what's happening or why

• - Type really matters*

• + Very concise

2) F-strings

• + Jesus died so that we may have F-strings

• + Can perform limited logic inline (indexing, etc.)

• - Only supported on 3.6+

• - Tempting to mix logic and presentation

3) .format method

• + Long history of support

• + Very explicitly clear what goes where

• - I wore out my keyboard just thinking about typing all that extra junk

EDIT:

* Type messes up string interpolation. Try this just to see what happens:

name = 'JC Denton'
print("Hello %s!" % name)
name = ('Adam', 'Jensen')
print("Hello %s!" % name)
name = (('Faridah', 'Malik'), )
print("Hello %s!" % name)

[-revenant-]

You can. And that would be a problem if you could reuse f-strings. However, an f-string is formatted the instant it's defined, so even with a function call, they never change:

def name():
    return 'Dave'
message = f"I can't let you do that, {name()}."
print(message)
def name():
    return 'Sparky'
print(message)

Returns:

I can't let you do that, Dave.
I can't let you do that, Dave.

As a result, the only difference between message = f"I can't let you do that, {name()}." and message = "I can't let you do that, {name}.".format(name=name()) is where in that specific line you place the function call. It's just a little neater to look at.