Resource management

2 snippets across 2 stacks — JavaScript, Python

JSJavaScript

Explicit Resource Management (using)

syntax

using resource = acquireResource();
await using resource = acquireAsyncResource();

example

class TempFile {
  constructor(path) {
    this.path = path;
    console.log(`Created: ${path}`);
  }

  [Symbol.dispose]() {
    console.log(`Cleaned up: ${this.path}`);
  }
}

{
  using file = new TempFile("/tmp/data.txt");
  // Use file here...
} // Automatically calls file[Symbol.dispose]() when block exits

output

"Created: /tmp/data.txt"
"Cleaned up: /tmp/data.txt"

Note TC39 Stage 3 (expected in ES2025/2026). Similar to Python's 'with' or C#'s 'using'. Guarantees cleanup even if an error is thrown. Use Symbol.asyncDispose for async cleanup.

PYPython

Context Managers (with Statement)

PY · File I/O

syntax

with expression as variable:
    ...

example

from contextlib import contextmanager

@contextmanager
def temp_directory():
    import tempfile, shutil
    path = tempfile.mkdtemp()
    try:
        yield path
    finally:
        shutil.rmtree(path)

with temp_directory() as tmp:
    print(f"Working in {tmp}")

Note The with statement guarantees cleanup code runs even if an exception occurs. Use contextlib.contextmanager to build custom context managers from generators.