**kwargs
**kwargs is Python function-parameter syntax that collects arbitrary keyword arguments into a dictionary keyed by their names.
Python How-To
kwargs is the conventional parameter name for a dictionary that collects variable-length keyword arguments passed to a Python function.
- How it is used
- Collects a variable number of keyword arguments in a function, including optional settings and decorator-wrapper calls.
- How deep it goes
- Explains dictionary packing, parameter placement, iteration, defaults, and the clarity trade-off; does not descend into interpreter internals.
- Examples
- Uses a grade-report function, optional calculation settings, and a decorator that fails when its wrapper accepts no arguments.
- What you can do after
- Build it from scratch in Python functions to collect optional keywords, read defaults, and write wrappers compatible with differing calling signatures.
Python Workout: 50 ten-minute exercises
Python function-parameter syntax that collects an arbitrary number of keyword arguments into a dictionary.
- How it is used
- Collects flexible named options for formatted output, dynamic dispatch, and constrained object queries.
- How deep it goes
- Explains dictionary creation and iteration through complete XML code, then applies the pattern to dispatch and filtering.
- Examples
- Uses XML-like tag generation, menu dispatch, and an Animal-query method accepting color and legs.
- What you can do after
- Build flexible Python functions that format, inspect, or dispatch arbitrary named arguments.
Read how Python Workout: 50 ten-minute exercises explains **kwargs →
The Well-Grounded Python Developer: How the pros use Python and Flask
A variadic keyword parameter is a function parameter that collects an arbitrary number of keyword arguments into a mapping.
- How it is used
- Uses a flexible keyword collection when functions need to receive, inspect, or forward varying named data.
- How deep it goes
- Defines the collection and lookup behavior, then cautions that undocumented keys and intentional forwarding require care.
- Examples
- Uses full_name to inspect fname, mname, and lname while contrasting flexible collection with explicitly named parameters.
- What you can do after
- Apply it via Python function definitions to collect, inspect, ignore, or forward arbitrary keyword arguments deliberately.
Read how The Well-Grounded Python Developer: How the pros use Python and Flask explains **kwargs →
Related concepts
- Mapkind of · A map is an associative data structure that stores key-value pairs and supports retrieving values by key.
- named argumentuses · A named argument is a function or command argument supplied by explicitly associating its value with a parameter name rather than relying solely on position.
- dispatch tableused by · A dispatch table is a mapping from operation or case identifiers to callable implementations selected and invoked at runtime.
- variadic argumentskind of · A variadic function or parameter accepts a variable number of arguments, often collecting the supplied values into a sequence of a specified type.
- parameterkind of · A model parameter is a numerical value, such as a weight or bias, that is learned or set to determine how a model computes outputs.
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