内部类型定义保留：在另一个结构内定义结构数组

Question

当我尝试在另一个结构中包含一个结构数组时，Julia抛出错误。

ERROR: LoadError: syntax: "grid = Cell[]" inside type definition is reserved

这是我要运行的测试代码。

struct Cell
    color::Int64
    location::Int64
    Cell(color::Int64,location::Int64) = new(color,location)
    Cell()=new(0,0)
end

struct Grid
    dimensions::Int64
    timestep::Int64
    grid=Cell[]
    courseGrain=Cell[]
    Grid(dimensions::Int64,timestep::Int64,grid_cell::Cell,courseGrain_cell::Cell) = 
    new(dimensions,timestep,push!(grid,grid_cell),push!(courseGrain,courseGrain_cell))
end

Answer 1

当前不允许在字段声明中定义默认字段值。参见https://github.com/JuliaLang/julia/issues/10146

要实现所需的功能，请将grid和courseGrain定义为类型为Cell（即Array{Cell, 1}或等效为Vector{Cell}）的一维数组，并处理构造函数中的默认情况。

struct Grid
    dimensions::Int64
    timestep::Int64
    grid::Vector{Cell}
    courseGrain::Vector{Cell}
    Grid(dimensions::Int64,timestep::Int64,grid_cell::Cell,courseGrain_cell::Cell) = 
    new(dimensions,timestep,[grid],[courseGrain_cell])
end

如果您希望构造函数之一创建一个空的grid或courseGrain，则可以在对Cell[]的调用中编写Vector{Cell}(undef, 0)或new。