Sample code for the article on f-strings

python-f-string/README.md

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+# Python's F-String: An Improved String Interpolation and Formatting Tool
+
+This folder provides the code examples for the Real Python tutorial [Python's F-String: An Improved String Interpolation and Formatting Tool](https://realpython.com/python-f-string-update/).

python-f-string/basic_f_strings.py

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+name = "Jane"
+age = 25
+f"Hello, {name}! You're {age} years old."
+
+f"{2 * 21}"

python-f-string/basic_format_method.py

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+name = "Jane"
+age = 25
+
+"Hello, {}! You're {} years old.".format(name, age)
+"Hello, {name}! You're {age} years old.".format(name="Jane", age=25)

python-f-string/basic_modulo.py

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+name = "Jane"
+age = 25
+
+"Hello, %s!" % name
+"Hello, %s! You're %s years old." % (name, age)

python-f-string/dictionaries.py

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+person = {"name": "Jane Doe", "age": 25}
+f"Hello, {person['name']}! You're {person['age']} years old."
+
+"Hello, {name}! You're {age} years old.".format(**person)
+"Hello, {name}!".format(**person)
+
+"Hello, %(name)s! You're %(age)s years old." % person
+"Hello, %(name)s!" % person

python-f-string/f_strings_doc_expressions.py

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+variable = "Some mysterious value"
+print(f"{variable = }")

python-f-string/f_strings_expressions.py

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+name = "Jane"
+age = 25
+
+f"Hello, {name.upper()}! You're {age} years old."
+f"{[2**n for n in range(3, 9)]}"

python-f-string/f_strings_representation.py

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+from person import Person
+
+jane = Person("Jane Doe", 25)
+
+f"{jane!s}"
+f"{jane!r}"

python-f-string/format_f_string.py

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+balance = 5425.9292
+f"Balance: ${balance:.2f}"
+
+heading = "Centered string"
+f"{heading:=^30}"
+
+integer = -1234567
+f"Comma as thousand separators: {integer:,}"
+sep = "_"
+f"User's thousand separators: {integer:{sep}}"
+
+floating_point = 1234567.9876
+f"Comma as thousand separator: {floating_point:,.2f}"
+
+date = (9, 6, 2023)
+f"Date: {date[0]:02}-{date[1]:02}-{date[2]}"
+date = (9, 26, 2023)
+f"Date: {date[0]:02}/{date[1]:02}/{date[2]}"

python-f-string/format_format_method.py

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+"Balance: ${:.2f}".format(5425.9292)
+"{:=^30}".format("Centered string")

python-f-string/format_modulo.py

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+"Balance: $%.2f" % 5425.9292
+print("Name: %s\nAge: %5s" % ("John", 35))

python-f-string/i18n_format_method.py

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+greeting_template = "{greeting} Pythonista!"
+
+greeting_en = "Good Morning!"
+greeting_es = "¡Buenos días!"
+greeting_fr = "Bonjour!"
+
+for greeting in (greeting_en, greeting_es, greeting_fr):
+    print(greeting_template.format(greeting=greeting))

python-f-string/logging_modulo.py

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+import logging
+
+msg_template = "Hey %s! You're using logging!"
+logging.warning(msg_template, "Pythonista")

python-f-string/performance.py

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+import timeit
+
+name = "Linda Smith"
+age = 40
+strings = {
+    "Modulo operator": "'Name: %s Age: %s' % (name, age)",
+    ".format() method": "'Name: {} Age: {}'.format(name, age)",
+    "f_string": "f'Name: {name} Age: {age}'",
+}
+
+
+def run_performance_test(strings):
+    max_length = len(max(strings, key=len))
+    for tool, string in strings.items():
+        time = timeit.timeit(string, number=1000000, globals=globals()) * 1000
+        print(f"{tool}: {time:>{max_length - len(tool) + 6}.2f} ms")

python-f-string/person.py

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+class Person:
+    def __init__(self, name, age):
+        self.name = name
+        self.age = age
+
+    def __str__(self):
+        return f"I'm {self.name}, and I'm {self.age} years old."
+
+    def __repr__(self):
+        return f"{type(self).__name__}(name='{self.name}', age={self.age})"

python-f-string/sample_v1.py

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+name = "Jane"
+age = 25
+
+print("Hello, %s! You're %s years old." % (name, age))

python-f-string/sample_v2.py

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+name = "Jane"
+age = 25
+
+print(f"Hello, {name}! You're {age} years old.")