看得见的@ 看不见的magic

入坑特性

• 宏: Expr -> Expr
• @less, @code_native
• ÷ ≠ ∈
• Condition + wait

Fire.jl

有的时候你写了一个函数，它需要很多参数

"Align two sequences locally"
function align(a::String, b::String; mismatch::Int=7, gap_open::Int=11,
               gap_extend::Int=2, threshold::Int=20)::Void
    ...
end

如果希望在命令行调用，你需要写很长一段代码 (ArgParse.jl)

using ArgParse

s = ArgParseSettings("Align two sequences locally")

@add_arg_table s begin
    "a"
        required = true
    "b"
        required = true
    "--mismatch"
        arg_type = Int
        default = 7
    "--gap_open"
        arg_type = Int
        default = 11
    "--gap_extend"
        arg_type = Int
        default = 2
    "--threshold"
        arg_type = Int
        default = 20
end

parsed_args = parse_args(s)

align(parsed_args["a"], parsed_args["b"]; parsed_args["mismatch"],
      parsed_args["gap_open"], parsed_args["gap_extend"], parsed_args["threshold"])

Fire.jl 的全部用法只需要2秒即可完全掌握

using Fire

"Align two sequences locally"
@main function align(a::String, b::String; mismatch::Int=7, gap_open::Int=11,
                     gap_extend::Int=2, threshold::Int=20)::Void
    ...
end

然后就会自动生成 --help，自动转换参数类型，智能处理 Vector, Bool 型关键字参数

➜ ~ julia align.jl
Need 2 positional arguments, see --help for what are them

➜ ~ julia align.jl --help
Align two sequences locally

Positional Arguments:
  a: String
  b: String

Optional Arguments:
  --mismatch: Int64 (default: 7)
  --gap_open: Int64 (default: 11)
  --gap_extend: Int64 (default: 2)
  --threshold: Int64 (default: 20)

➜ ~ julia align.jl --threshold 15 \
> AAAGCGCGAAGCTACGTAGCTGACTGATCGTACGTACGTCGTAGC \
> GCGCGAAGCTACGTAGAAACTGACTGATCGTACCTACGTCGTAGC

GCGCGAAGCTACGTAG---CTGACTGATCGTACGTACGTCGTAGC
||||||||||||||||   |||||||||||||| |||||||||||
GCGCGAAGCTACGTAGAAACTGACTGATCGTACCTACGTCGTAGC

安装方法: Pkg.clone("https://github.com/ylxdzsw/Fire.jl")

JsonBuilder.jl

如果需要生成一个具有固定字段的 JSON，很容易想到两个方案:

time   = ["2017-01-17", "2017-01-18", "2017-01-19", ...]
open   = [118.339996, 119.400002, 120.449997, ...]
top    = [120.239998, 120.5, 120.089996, ...]
bottom = [118.220001, 119.709999, 119.370003, ...]
close  = [120, 119.989998, 119.779999, ...]

approch1 = """{
    "x":     [$(join(map(x->"\"$x\"", time), ","))],
    "open":  [$(join(open, ","))],
    "close": [$(join(close, ","))],
    "high":  [$(join(top, ","))],
    "low":   [$(join(bottom, ","))],
    "decreasing": {"line": {"color": "#7F7F7F"}},
    "increasing": {"line": {"color": "#17BECF"}},
    "line":  {"color": "rgba(31,119,180,1)"},
    "type":  "ohlc",
    "xaxis": "x",
    "yaxis": "y"
}"""

approch2 = JSON.json(Dict(
    "x"          => time,
    "open"       => open,
    "close"      => close,
    "high"       => top,
    "low"        => bottom,
    "decreasing" => Dict("line"  => Dict("color" => "#7F7F7F")),
    "increasing" => Dict("line"  => Dict("color" => "#17BECF")),
    "line"       => Dict("color" => "rgba(31,119,180,1)"),
    "type"       => "ohlc",
    "xaxis"      => "x",
    "yaxis"      => "y"
))

拼字符串的方法有几个问题：

而直接使用 JSON.jl 又有另外几个问题：

JsonBuilder.jl 使用类似 JavaScript 的高兼容性语法，采取特殊的插值规则，并且在编译期完成格式解析

approch3 = @json """{
    x: $time,
    open: $open,
    close: $close,
    high: $top,
    low: $bottom,
    decreasing: {line: {color: "#7F7F7F"}},
    increasing: {line: {color: "#17BECF"}},
    line: {color: "rgba(31,119,180,1)"},
    type: "ohlc",
    xaxis: "x",
    yaxis: "y"
}"""

JsonBuilder 具备以下优势

安装方法: Pkg.clone("https://github.com/ylxdzsw/JsonBuilder.jl")

RedisAlchemy.jl

使用 Redis 来(伪)持久化应用数据，或者协调多进程并行计算，而不需要学习 Redis

using RedisAlchemy

conn = RedisConnectionPool(10)

list = RedisList{String}("task")

push!(list, 2)

unshift!(list, 3)

length(list)

list[1:2]

sort!(list)

list[:]

• 支持 String, List, Dict, Pipe, Blob 等多种类型
• 使用和 Julia 内建类型一样的函数
• 连接池适合 Julia 协程进行阻塞操作

安装方法: Pkg.clone("https://github.com/ylxdzsw/RedisAlchemy.jl")