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Use f-strings in argparse HOWTO #20070

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May 21, 2020
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Use f-strings in argparse HOWTO #20070

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34 changes: 17 additions & 17 deletions Doc/howto/argparse.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -353,7 +353,7 @@ Our program keeps growing in complexity::
args = parser.parse_args()
answer = args.square**2
if args.verbose:
print("the square of {} equals {}".format(args.square, answer))
print(f"the square of {args.square} equals {answer}")
else:
print(answer)

Expand Down Expand Up @@ -387,9 +387,9 @@ multiple verbosity values, and actually get to use them::
args = parser.parse_args()
answer = args.square**2
if args.verbosity == 2:
print("the square of {} equals {}".format(args.square, answer))
print(f"the square of {args.square} equals {answer}")
elif args.verbosity == 1:
print("{}^2 == {}".format(args.square, answer))
print(f"{args.square}^2 == {answer}")
else:
print(answer)

Expand Down Expand Up @@ -421,9 +421,9 @@ Let's fix it by restricting the values the ``--verbosity`` option can accept::
args = parser.parse_args()
answer = args.square**2
if args.verbosity == 2:
print("the square of {} equals {}".format(args.square, answer))
print(f"the square of {args.square} equals {answer}")
elif args.verbosity == 1:
print("{}^2 == {}".format(args.square, answer))
print(f"{args.square}^2 == {answer}")
else:
print(answer)

Expand Down Expand Up @@ -461,9 +461,9 @@ verbosity argument (check the output of ``python --help``)::
args = parser.parse_args()
answer = args.square**2
if args.verbosity == 2:
print("the square of {} equals {}".format(args.square, answer))
print(f"the square of {args.square} equals {answer}")
elif args.verbosity == 1:
print("{}^2 == {}".format(args.square, answer))
print(f"{args.square}^2 == {answer}")
else:
print(answer)

Expand Down Expand Up @@ -529,9 +529,9 @@ Let's fix::

# bugfix: replace == with >=
if args.verbosity >= 2:
print("the square of {} equals {}".format(args.square, answer))
print(f"the square of {args.square} equals {answer}")
elif args.verbosity >= 1:
print("{}^2 == {}".format(args.square, answer))
print(f"{args.square}^2 == {answer}")
else:
print(answer)

Expand Down Expand Up @@ -566,9 +566,9 @@ Let's fix that bug::
args = parser.parse_args()
answer = args.square**2
if args.verbosity >= 2:
print("the square of {} equals {}".format(args.square, answer))
print(f"the square of {args.square} equals {answer}")
elif args.verbosity >= 1:
print("{}^2 == {}".format(args.square, answer))
print(f"{args.square}^2 == {answer}")
else:
print(answer)

Expand Down Expand Up @@ -606,9 +606,9 @@ not just squares::
args = parser.parse_args()
answer = args.x**args.y
if args.verbosity >= 2:
print("{} to the power {} equals {}".format(args.x, args.y, answer))
print(f"{args.x} to the power {args.y} equals {answer}")
elif args.verbosity >= 1:
print("{}^{} == {}".format(args.x, args.y, answer))
print(f"{args.x}^{args.y} == {answer}")
else:
print(answer)

Expand Down Expand Up @@ -645,9 +645,9 @@ to display *more* text instead::
args = parser.parse_args()
answer = args.x**args.y
if args.verbosity >= 2:
print("Running '{}'".format(__file__))
print(f"Running '{__file__}'")
if args.verbosity >= 1:
print("{}^{} == ".format(args.x, args.y), end="")
print(f"{args.x}^{args.y} == ", end="")
print(answer)

Output:
Expand Down Expand Up @@ -688,9 +688,9 @@ which will be the opposite of the ``--verbose`` one::
if args.quiet:
print(answer)
elif args.verbose:
print("{} to the power {} equals {}".format(args.x, args.y, answer))
print(f"{args.x} to the power {args.y} equals {answer}")
else:
print("{}^{} == {}".format(args.x, args.y, answer))
print(f"{args.x}^{args.y} == {answer}")

Our program is now simpler, and we've lost some functionality for the sake of
demonstration. Anyways, here's the output:
Expand Down