英文:
What does this line of code mean in Julia Programming Language
问题
function commence(args::Vector{String})
这一行的意思是，定义一个名为"commence"的函数，该函数接受一个名为"args"的参数，参数的类型限定为Vector{String}，即一个存储字符串的向量。
英文:
function commence(args::Vector{String})
What I would like to know is, what does this line mean? Particularly, what does the argument of commence, "(args::Vector{String})" mean?
答案1
得分: 4
这行代码指示了一个名为commence的函数的定义，它接受一个名为args的单一参数。::Vector{String}部分指定只有字符串向量，也就是类型为Vector{String}的对象，才会被该函数接受。请参考以下演示：
julia> function commence(args::Vector{String})
@show args
nothing
end
commence (generic function with 1 method)
julia> commence([1,2,3])
ERROR: MethodError: no method matching commence(::Array{Int64,1})
Closest candidates are:
commence(::Array{String,1}) at REPL[1]:2
Stacktrace:
[1] top-level scope at REPL[2]:1
julia> commence("asd","test")
ERROR: MethodError: no method matching commence(::String, ::String)
Stacktrace:
[1] top-level scope at REPL[3]:1
julia> commence(["asd","test"]) # 正常工作，因为args的类型是Vector{String}
args = ["asd", "test"]
我建议你阅读手册，特别是这部分，以了解更多关于Julia中函数的信息。
英文:
The line indicates the definition of a function named commence which takes a single argument args. The ::Vector{String} bit specifies that only vectors of strings, i.e. objects of type Vector{String}, will be accepted by the function. See the following demonstration:
julia> function commence(args::Vector{String})
@show args
nothing
end
commence (generic function with 1 method)
julia> commence([1,2,3])
ERROR: MethodError: no method matching commence(::Array{Int64,1})
Closest candidates are:
commence(::Array{String,1}) at REPL[1]:2
Stacktrace:
[1] top-level scope at REPL[2]:1
julia> commence("asd","test")
ERROR: MethodError: no method matching commence(::String, ::String)
Stacktrace:
[1] top-level scope at REPL[3]:1
julia> commence(["asd","test"]) # works, since typeof(args) == Vector{String}
args = ["asd", "test"]
I recommend you read through the manual, in particular this part, to learn more about functions in Julia.
答案2
得分: 0
:: 表示强制类型，类似于 typeassert()。
还可参考 https://docs.julialang.org/en/v1/base/punctuation/ [Julia 标点][1]
英文:
:: means enforce the type similar to typeassert().
Also see https://docs.julialang.org/en/v1/base/punctuation/ [Julia Puntuation][1]
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