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defaultdict-proxy
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- Version published
- Maintainers
- 1
- Weekly downloads
- 701
- decreased by-13.46%
Weekly downloads
Readme
JavaScript defaultdict
This is a port of python's defaultdict to JavaScript. It uses proxies to create objects that return values other than undefined for attributes that haven't yet been set.
This package needs native Proxy support to work.
Install
yarn add defaultdict-proxy
Usage
If called with undefined, null, a boolean, number, string or symbol, defaultdict returns a proxy object that returns this value for unset attributes. If called with an array or object, accessing unset attributes returns a shallow copy of the array or object. If defaultdict is given a function, it returns a proxy object that has unset attributes initialized to the result of executing the function.
import defaultdict from 'defaultdict-proxy';
// This defaultdict returns fresh empty arrays for unset attributes
const dd1 = defaultdict([]);
// defaultdicts act like normal objects
dd1.a = { b: 0 };
dd1.a.b === 0; // true
// We can use attributes without setting them first
dd1.b.push(42);
dd1.b; // [42]
dd1.c; // []
dd1.d === dd1.e; // false, every attribute gets its own copy
// A defaultdict that initializes unset attributes with the time of their
// first access
const dd2 = defaultdict(() => new Date());
// The attribute initialization function is given the name of the attribute
// as a parameter. This defaultdict initializes unset attributes to their
// name
const dd3 = defaultdict(attr => attr);
dd3.blah // 'blah'
// To create defaultdicts that initialize unset attributes with functions,
// we have to pass defaultdict a higher order function. In this example,
// unset attribute accesses return the identity function.
const dd4 = defaultdict(() => x => x);
License
MIT
FAQs
This is a port of [python's defaultdict](https://docs.python.org/2/library/collections.html#defaultdict-objects) to JavaScript. It uses proxies to create objects that return values other than ```undefined``` for attributes that haven't yet been set.
The npm package defaultdict-proxy receives a total of 523 weekly downloads. As such, defaultdict-proxy popularity was classified as not popular.
We found that defaultdict-proxy demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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