Unpack

Unpack is a verb with several related meanings. In everyday use, to unpack means to remove items from a container, wrapper, or package and prepare them for use. The process may involve inspecting contents, checking for damage, and organizing items for storage or disposal. In logistics and shipping, unpacking may occur at warehouses or customer premises; improper unpacking can pose safety risks or lead to damage.

In computing and data processing, unpack refers to converting data from a compact or encoded form into a more accessible, structured representation. This can involve reading binary or compressed data and expanding it into fields, variables, or data structures. A common example is unpacking in languages that bind binary data to variables, such as Python’s struct module, where a byte string is unpacked into integers, floats, or strings according to a format specification.

Programming languages also use unpacking as a syntax for assigning multiple variables at once or for passing sequences as arguments. In Python, tuple or list unpacking allows statements like a, b, c = (1, 2, 3), and starred expressions enable gathering or scattering remaining items (for example, x, *rest, y = [1, 2, 3, 4]). Python also supports unpacking in function calls with the * and ** operators. JavaScript and other languages offer similar destructuring or pattern-matching features to extract values from arrays or objects.

Other uses include unpacking in data formats and protocols where dense representations are decoded for processing, or in software dealing with archive formats where file contents are extracted from a container.