"""
Урок 22. Строки: форматирование — весь код примеров одним файлом.

Источник: subjects/python-fundamentals/course/lessons/22-strings-formatting/examples.html
Файл собран автоматически (tools/build_lesson_examples.py): правьте страницу урока.
Запуск: python lesson-22.py
"""



# ====================================================================
# Пример 1. Строка — неизменяемая последовательность
# ====================================================================
name = "Alice"
upper_name = name.upper()
print(name)          # Alice — исходная строка не изменилась
print(upper_name)    # ALICE — метод вернул новую строку

try:
    name[0] = "a"
except TypeError as error:
    print("TypeError:", error)
    # TypeError: 'str' object does not support item assignment


# ====================================================================
# Пример 2. Конкатенация + и повторение *
# ====================================================================
first = "Python"
second = "Fundamentals"
title = first + " " + second
print(title)             # Python Fundamentals

separator = "-" * 20
print(separator)         # --------------------

greeting = "Hi! " * 3
print(greeting)          # Hi! Hi! Hi!


# ====================================================================
# Пример 3. f-strings: базовое использование
# ====================================================================
name = "Bob"
age = 25
message = f"My name is {name} and I am {age} years old."
print(message)
# My name is Bob and I am 25 years old.


# ====================================================================
# Пример 4. f-strings: выражения и вызовы методов внутри {}
# ====================================================================
word = "python"
x, y = 10, 20
print(f"The sum of {x} and {y} is {x + y}.")
# The sum of 10 and 20 is 30.
print(f"'{word}' in upper case: {word.upper()}, length: {len(word)}.")
# 'python' in upper case: PYTHON, length: 6.


# ====================================================================
# Пример 5. Спецификаторы формата: точность, ширина, выравнивание, нули
# ====================================================================
pi = 3.14159
price = 1234567.89
print(f"Pi ≈ {pi:.2f}")            # Pi ≈ 3.14
print(f"Price: ${price:,.2f}")     # Price: $1,234,567.89

label = "Python"
print(f"[{label:<10}]")   # [Python    ]
print(f"[{label:>10}]")   # [    Python]
print(f"[{label:^10}]")   # [  Python  ]

number = 42
print(f"{number:05}")     # 00042


# ====================================================================
# Пример 6. str.format() как альтернатива f-strings
# ====================================================================
name = "Carol"
age = 28
print("Name: {}, Age: {}".format(name, age))
# Name: Carol, Age: 28
print("Name: {n}, Age: {a}".format(n=name, a=age))
# Name: Carol, Age: 28

template = "Hello, {}!"   # шаблон хранится отдельно от данных
print(template.format("World"))
# Hello, World!


# ====================================================================
# Пример 7. Именованные плейсхолдеры и .format_map()
# ====================================================================
user = {"name": "Dave", "age": 41}
print("Name: {name}, Age: {age}".format_map(user))
# Name: Dave, Age: 41


# ====================================================================
# Пример 8. Экранирование фигурных скобок {{ }}
# ====================================================================
value = 5
print(f"{{value}} equals {value}")
# {value} equals 5
print("Use {{}} for literal braces: {}".format("like this"))
# Use {} for literal braces: like this


# ====================================================================
# Пример 9. Отладочный вывод f"{x=}"
# ====================================================================
count = 7
print(f"{count=}")
# count=7

items = ["a", "b", "c"]
print(f"{len(items)=}")
# len(items)=3


# ====================================================================
# Пример 10. Полезные строковые методы для подготовки текста
# ====================================================================
raw = "  Python Fundamentals  "
clean = raw.strip()
print(f"'{clean}'")
# 'Python Fundamentals'

parts = clean.split()
print(parts)
# ['Python', 'Fundamentals']

joined = "-".join(parts)
print(joined)
# Python-Fundamentals

print(clean.upper(), clean.lower())
# PYTHON FUNDAMENTALS python fundamentals

code = "7"
print(code.zfill(4))
# 0007


# ====================================================================
# Пример 11. Границы применимости и типичные ошибки
# ====================================================================
data = {"key": "value"}
print(f"{data['key']}")
# value — разные кавычки: строка снаружи f"...", ключ внутри '...'

source_with_same_quotes = 'f"{data["key"]}"'
try:
    compile(source_with_same_quotes, "<demo>", "eval")
except SyntaxError as error:
    print("SyntaxError:", error)
    # SyntaxError: f-string: unmatched '[' (<demo>, line 1)

text = "abc"
before_id = id(text)
text += "d"
print(text, id(text) == before_id)
# abcd False — новая строка в другом месте памяти