JuliaLang/julia

make KeyIterator and ValueIterator more array-like

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#10,092 opened on Feb 5, 2015

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 (9 comments) (3 reactions) (0 assignees)Julia (48,709 stars) (5,773 forks)batch import
collectionshelp wanted

Description

When have d = Dict(:foo => 12.34, "bar" => 567) and you write keys(d) you get a Base.KeyIterator object, which is fast and cheap to construct from the dictionary d. You can write collect(keys(d)) to get an array of keys, but you have to do this unfortunately often. It would be a good self-contained project to add more array-like behaviors to KeyIterator and the corresponding ValueIterator types so that things like keys(d)[1] and values(d)[end] work as expected.

Contributor guide

Tech stack
None
Domain
developer experienceperformance
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Julia basicsunderstanding of iterators
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Examine the current implementation of KeyIterator and ValueIterator in base/dict.jl. Understand how indexing is currently handled and what methods need to be added to support keys(d)[i] and values(d)[end]. Consider implementing getindex and similar array like methods while ensuring performance is not degraded. Check existing tests for these types and add new tests.