Reusable f-strings
Unify on one format style. With F-yeah Just add parentheses and be on your way.
Usage
Keep using f-string formatting, but when you need to re-use a template, use the
f function instead of the f literal
These two lines are equivalent
print(f'about to put {os.getpid()} to sleep')
print(f('about to put {os.getpid()} to sleep'))
# "about to put 421 to sleep"No longer choose between copying around f-string literals or continuing to use old-style format() calls.
Instead of this
def mul(value):
assert isinstance(value, int), 'Expected value to be an integer, got {type(value)} instead'
return value * value
def pow(value):
assert isinstance(value, int), 'Expected value to be an integer, got {type(value)} instead'
return value ** valueOr this
bad_check = 'expected value to be an integer, got {type(value)} instead'
def mul(value):
assert isinstance(value, int), bad_check.format(value=value)
return value * value
def pow(value):
assert isinstance(value, int), bad_check.format(value=value)
return value ** valueJust write the template once to get consistent strings that stay in sync.
from fyeah import f
bad_check = 'Expected value to be an integer, got {type(value)} instead'
def mul(value):
assert isinstance(value, int), f(bad_check)
return value * value
def pow(value):
assert isinstance(value, int), f(bad_check)
return value ** valueWhy would I use a function over the literal?
f-string literals are evaluated when they are created. This makes situations like the following impossible.
class BaseListRunner:
command = ['ls']
args = []
notify_running = '{self.__class__.__name__} is executing {self.command} with "{" ".join(self.args)}"'
def run(self):
log.debug(f(self.notify_running))
subprocess.call(self.command + args)
class AllListRunner:
def __init__(self):
self.args.append('-A')
AllListRunner().run()
# DEBUG: AllListRunnner is executing ls with "-A"Why would I use F-yeah instead of the format() builtin?
Although the format mini-language and f-strings share a lot of syntax, they have diverged somewhat. You could use only format() for all your strings, but format() is more verbose and less flexible as compared to f-strings; enough so that f-strings were adopted into the language. Using F-yeah makes the following possible.
G_COUNT = 0
count_tracker = '{G_COUNT=} at {datetime.datetime.utcnow():%H:%M:%S}'
def acquire():
G_COUNT += 1
log.debug(f(count_tracker))
def release():
G_COUNT -= 1
log.debug(f(count_tracker))
def check():
log.debug(f(count_tracker))
return G_COUNT
