JuliaDiff / JuliaDiff/ChainRulesCore.jl

Implement getindex and view for AbstractZero

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good first issue LinearOperators
Dominant language
Julia
Stars
267
Forks
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PR merge metrics
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Description

It would be handy to add something like the following overloads:

getindex(x::AbstractZero, i..) = x
view(x::AbstractZero, i...) = x

since a Zero if interpreted as an array can only have Zero subarrays or elements. This would make it so rules that depend only on certain elements of a differential don't necessarily have to special-case to work around possible Zero arrays but can instead just index them as normal.

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating AbstractZero and the existing getindex and view definitions in the Julia source. Add the requested behavior, then run the relevant test suite and verify that indexing or viewing an AbstractZero returns the same Zero value.

Written by the indexing model from the issue text.

Assessment

Tech stack
julia
Domain
backend-api-design
Issue type
Feature
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
35/100

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