Hacktoberfest 2026：维护者为十月标记出来的 issue，仍然开放、适合新手。 浏览 Hacktoberfest issue

Array Constructors - `similar`

未关闭
  • 哪里不对？
#130 9 条评论 0 个 reaction 已指派 0 人 在 GitHub 查看

还没有人认领这个 Issue。

评估

难度
5/5
预计耗时
一周以上
新手友好度
15/100
Issue 类型
功能
描述清晰度
需要澄清
活跃度
停滞
技术栈
julia
领域
data

调研方向

首先阅读链接的三个 Julia issue，以及为 allocate_memory、preserve、initialize 和 instantiate 提出的草案。该 issue 没有指明 repository 文件或测试，而 done 的定义也仅限于就分离数组构造职责的设计达成一致。

由索引模型根据 Issue 内容生成。

描述

I think we are in a good place to start working on array constructors (would also make documenting examples a whole lot easier). This brings up stuff related to similar:

I'm not convinced there's a silver bullet for array constructors, but I think we could at least find a solution to what similar is often trying to do, allow generic method definition without worrying about array specific constructors. I think we actually need to break up what similar does into several pieces though

  1. allocate memory - a buffer/Ref that is safer than a pointer
  2. do something to the memory - probably fastest on pointers
  3. create user facing instance - e.g., Array

I haven't worked out all the details but here's some of the cleaner code I have so far that might support this.

""" allocate_memory(x, args...) """  # step 1 allocates memory with corresponding device to `x` and axes
function allocate_memory(x)  end

""" preserve(f, x, y) """  # step 2 operate on pointers and permit novel garbage collection approaches
preserve(f, x::X) where {X} = preserve(f, x, device(X))
preserve(f, x::X, ::CPUIndex) where {X} = f(x)
function preserve(f, x::X, ::CPUPointer) where {X}
    GC.@preserve x out = f(pointer(x))
    return out
end
preserve(f, x::X, y::Y) where {X,Y} = preserve(p_x -> preserve(Base.Fix1(op, p_x), y), x)


""" as_immutable """
function as_immutable(x) end

""" initialize(original, new_data) """ # step 3 turn processed buffer into user facing array
function initialize(x::X, data) where {X}
    if !ismutable(X)
        return as_immutable(data)
    else
        return data
    end
end

""" instantiate(f, x, allocator, initiializer) """
instantiate(f, x, allocator, initiializer) = initiializer(x, preserve(f, allocator(x),  x))
instantiate(f, x, allocator) = (f, x, allocator, initiialize)
instantiate(f, x) = (f, x, allocate_memory)

The reason I think separating things out like this is helpful is because it turns this function from base like this

function rotr90(A::AbstractMatrix)
    ind1, ind2 = axes(A)
    B = similar(A, (ind2,ind1))
    m = first(ind1)+last(ind1)
    for i=ind1, j=axes(A,2)
        B[j,m-i] = A[i,j]
    end
    return B
end

into this

function rotr90(A)
    ind1, ind2 = axes(A)
    return instantiate(A, x -> allocate_memory(x, (ind2, ind1))) do a, b
        m = first(ind1)+last(ind1)
        for i=ind1, j=axes(A,2)
            b[j,m-i] = a[i,j]
        end
    end
end

This means that new array types typically wouldn't need to change rotr90 but would just change their allocators and initializers. I'm not super familiar with how jagged arrays work but we could have allocate_memory take in device and memory layout info for this.

主要语言
Julia
星标
140
派生
45
平均合并
1 分钟
30 天内合并 PR
1

环境准备

这个项目没有提供开发容器、Dockerfile 或贡献指南，环境需要你自己搭建：先看它的 README，通用步骤见我们的新手贡献指南。

从这里开始

  1. 先读完整个 Issue，再读项目的贡献指南。
  2. 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
  3. Fork 仓库，在一个分支上完成修改。
  4. 提交 Pull Request，并在描述里引用这个 Issue 编号。

JuliaArrays/ArrayInterface.jl 的其他 Issue

查看 JuliaArrays/ArrayInterface.jl 的全部 Issue

相似的 Issue

更多 Julia Issue

把新 issue 发到你的邮箱

精选适合新手参与的 GitHub issue 摘要。