diff --git a/README.md b/README.md index 202b25f7..e8186cb2 100644 --- a/README.md +++ b/README.md @@ -14,8 +14,9 @@ Contents **   ** **4. System:** **        ** **[`Exit`](#exit)**__,__ **[`Print`](#print)**__,__ **[`Input`](#input)**__,__ **[`Command_Line_Arguments`](#command-line-arguments)**__,__ **[`Open`](#open)**__,__ **[`Path`](#paths)**__,__ **[`OS_Commands`](#os-commands)**__.__ **   ** **5. Data:** **             ** **[`JSON`](#json)**__,__ **[`Pickle`](#pickle)**__,__ **[`CSV`](#csv)**__,__ **[`SQLite`](#sqlite)**__,__ **[`Bytes`](#bytes)**__,__ **[`Struct`](#struct)**__,__ **[`Array`](#array)**__,__ **[`Memory_View`](#memory-view)**__,__ **[`Deque`](#deque)**__.__ **   ** **6. Advanced:** **   ** **[`Operator`](#operator)**__,__ **[`Match_Stmt`](#match-statement)**__,__ **[`Logging`](#logging)**__,__ **[`Introspection`](#introspection)**__,__ **[`Threading`](#threading)**__,__ **[`Coroutines`](#coroutines)**__.__ -**   ** **7. Libraries:** **      ** **[`Progress_Bar`](#progress-bar)**__,__ **[`Plot`](#plot)**__,__ **[`Table`](#table)**__,__ **[`Console_App`](#console-app)**__,__ **[`GUI`](#gui-app)**__,__ **[`Scraping`](#scraping)**__,__ **[`Web`](#web-app)**__,__ **[`Profile`](#profiling)**__.__ -**   ** **8. Multimedia:** **  ** **[`NumPy`](#numpy)**__,__ **[`Image`](#image)**__,__ **[`Animation`](#animation)**__,__ **[`Audio`](#audio)**__,__ **[`Synthesizer`](#synthesizer)**__,__ **[`Pygame`](#pygame)**__,__ **[`Pandas`](#pandas)**__,__ **[`Plotly`](#plotly)**__.__ +**   ** **7. Modern:** **     ** **[`Union_Type`](#union-type-operator)**__,__ **[`Walrus`](#walrus-operator)**__,__ **[`Except_Groups`](#exception-groups)**__,__ **[`TOML`](#toml-support)**__,__ **[`Context_Mgr`](#context-managers)**__,__ **[`Task_Groups`](#task-groups)**__,__ **[`Type_Params`](#type-parameter-syntax)**__.__ +**   ** **8. Libraries:** **      ** **[`Progress_Bar`](#progress-bar)**__,__ **[`Plot`](#plot)**__,__ **[`Table`](#table)**__,__ **[`Console_App`](#console-app)**__,__ **[`GUI`](#gui-app)**__,__ **[`Scraping`](#scraping)**__,__ **[`Web`](#web-app)**__,__ **[`Profile`](#profiling)**__.__ +**   ** **9. Multimedia:** **  ** **[`NumPy`](#numpy)**__,__ **[`Image`](#image)**__,__ **[`Animation`](#animation)**__,__ **[`Audio`](#audio)**__,__ **[`Synthesizer`](#synthesizer)**__,__ **[`Pygame`](#pygame)**__,__ **[`Pandas`](#pandas)**__,__ **[`Plotly`](#plotly)**__.__ Main @@ -2386,6 +2387,277 @@ if __name__ == '__main__':
+Modern Python Features +====================== +**Features introduced in Python 3.10, 3.11, and 3.12.** + + +Union Type Operator +------------------- +**Modern syntax for type hints using the `|` operator (Python 3.10+).** +```python +def process(value: int | float | None) -> str | None: # Instead of Union[int, float, None] + if value is None: + return None + return str(value) +``` + +```python +from typing import TypeAlias + +Number: TypeAlias = int | float # Type alias with union operator. +Result: TypeAlias = dict[str, Number] | list[Number] # Complex type aliases. +``` + +```python + = int | str | None # Can be used in isinstance() checks. +if isinstance(value, int | str): # Checks if value is int or str. + ... +``` + + +Walrus Operator +--------------- +**Assignment expression operator `:=` assigns and returns a value (Python 3.8+).** +```python +if (n := len(data)) > 10: # Assigns len(data) to n and checks it. + print(f'List is too long ({n} elements)') +``` + +```python +while (line := file.readline()) != '': # Reads and checks in one expression. + process(line) +``` + +```python +[y for x in data if (y := transform(x)) is not None] # Avoids calling transform() twice. +``` + +```python +if (match := re.search(pattern, text)): # Assigns match object if found. + print(match.group(1)) +``` + + +Exception Groups +---------------- +**Mechanism for raising and handling multiple exceptions simultaneously (Python 3.11+).** +```python +try: + raise ExceptionGroup('Multiple errors', [ + ValueError('Invalid value'), + TypeError('Wrong type'), + KeyError('Missing key') + ]) +except* ValueError as e: # Catches only ValueError from the group. + print(f'Value errors: {e.exceptions}') +except* TypeError as e: # Catches only TypeError from the group. + print(f'Type errors: {e.exceptions}') +``` + +```python +errors = [] +for item in items: + try: + process(item) + except Exception as e: + errors.append(e) +if errors: + raise ExceptionGroup('Processing failed', errors) # Raises all collected errors at once. +``` + +* **Use `except*` instead of `except` to handle exception groups. Each `except*` clause catches matching exceptions from the group.** +* **An `ExceptionGroup` can contain other `ExceptionGroup` instances, creating nested error hierarchies.** + + +TOML Support +------------ +**Built-in support for TOML configuration files (Python 3.11+).** +```python +import tomllib # Read-only TOML parser in stdlib. + +with open('config.toml', 'rb') as file: # Must open in binary mode. + config = tomllib.load(file) +``` + +```python +toml_string = ''' +title = "My Application" + +[database] +server = "localhost" +port = 5432 +enabled = true +''' + +config = tomllib.loads(toml_string) # Parse TOML from string. +print(config['database']['server']) # 'localhost' +``` + +* **For writing TOML files, use the third-party `tomli-w` or `tomlkit` packages.** +* **TOML is commonly used in `pyproject.toml` for Python project configuration.** + + +Context Managers +---------------- +**Objects that define `__enter__()` and `__exit__()` methods for resource management.** +```python +with open('file.txt') as file: # File is automatically closed. + content = file.read() +``` + +```python +with lock: # Lock is acquired and released. + critical_section() +``` + +### Multiple Context Managers +```python +with open('in.txt') as infile, open('out.txt', 'w') as outfile: + outfile.write(infile.read()) +``` + +```python +with ( # Parenthesized syntax (Python 3.10+). + open('file1.txt') as f1, + open('file2.txt') as f2, + open('file3.txt') as f3 +): + process(f1, f2, f3) +``` + +### Creating Context Managers +```python +from contextlib import contextmanager + +@contextmanager +def tag(name): + print(f'<{name}>') # Runs on entry. + yield # Control returns to with block. + print(f'') # Runs on exit. + +with tag('h1'): + print('Title') +# Output:

\nTitle\n

+``` + +```python +class DatabaseConnection: + def __enter__(self): + self.conn = create_connection() + return self.conn + + def __exit__(self, exc_type, exc_val, exc_tb): + self.conn.close() + return False # Propagates exceptions (True suppresses). + +with DatabaseConnection() as conn: + conn.execute('SELECT * FROM users') +``` + +### Async Context Managers +```python +class AsyncResource: + async def __aenter__(self): + self.resource = await acquire_resource() + return self.resource + + async def __aexit__(self, exc_type, exc_val, exc_tb): + await self.resource.close() + return False + +async with AsyncResource() as resource: + await resource.process() +``` + + +Task Groups +----------- +**Simplified async task management with automatic cleanup (Python 3.11+).** +```python +import asyncio + +async def fetch_data(url): + await asyncio.sleep(1) + return f'Data from {url}' + +async def main(): + async with asyncio.TaskGroup() as tg: # All tasks are awaited automatically. + task1 = tg.create_task(fetch_data('url1')) + task2 = tg.create_task(fetch_data('url2')) + task3 = tg.create_task(fetch_data('url3')) + + # All tasks are complete here + print(task1.result(), task2.result(), task3.result()) +``` + +* **If any task raises an exception, all other tasks are cancelled and exceptions are collected into an `ExceptionGroup`.** +* **TaskGroup ensures all tasks are properly awaited and cleaned up, even if errors occur.** + + +Type Parameter Syntax +--------------------- +**Simplified syntax for generic classes and functions (Python 3.12+).** +```python +def first[T](items: list[T]) -> T: # Generic function with type parameter. + return items[0] +``` + +```python +class Stack[T]: # Generic class with type parameter. + def __init__(self): + self._items: list[T] = [] + + def push(self, item: T) -> None: + self._items.append(item) + + def pop(self) -> T: + return self._items.pop() +``` + +```python +class Pair[S, T]: # Multiple type parameters. + def __init__(self, first: S, second: T): + self.first = first + self.second = second +``` + +* **This is equivalent to using `typing.Generic` but with cleaner syntax.** +* **Type parameters are automatically available within the class or function scope.** + + +Improved Error Messages +----------------------- +**Python 3.10+ provides more detailed and helpful error messages.** + +```python +# Before Python 3.10: +# TypeError: unsupported operand type(s) for +: 'int' and 'str' + +# Python 3.10+: +# TypeError: unsupported operand type(s) for +: 'int' and 'str' +# result = 1 + '2' +# ~~^~~~~ +``` + +```python +# Improved AttributeError suggestions: +# AttributeError: 'dict' object has no attribute 'appen'. Did you mean: 'append'? +``` + +```python +# Better SyntaxError messages with precise location: +# SyntaxError: invalid syntax. Perhaps you forgot a comma? +# data = [ +# 'item1' +# 'item2' # Missing comma highlighted +# ] +``` + +* **Error messages now include visual indicators (^) pointing to the exact problem location.** +* **Python suggests corrections for common typos in attribute and name errors.** + + Libraries =========