Will OpenResty consider adding a module for functions like map, reduce and filter?

xiangnanscu · 2016-08-08T09:51:21+00:00

Hi,i'm using srcache to store upstream responses.In header_filter_by_lua_block, it seems that changing response header using `ngx.header["X-My-...

Will OpenResty consider adding a module for functions like map, reduce and filter?

xiangnanscu

for example, currently I use following base functions in my own module:

local function map(func, tbl)
    local res = {}
    for i=1, #tbl do
        res[i] = func(tbl[i])
    end
    return res
end
local function filter(func, seq)
    local res = {}
    for i, v in ipairs(seq) do
        if func(v)  == true then
            res[#res+1] = v
        end
    end
    return res
end
local function copy(old)
    local res = {}
    for i, v in pairs(old) do
        res[i] = v
    end
    return res
end
local function update(self, other)
    for i, v in pairs(other) do
        self[i] = v
    end
    return self
end
local function extend(self, other)
    for i, v in ipairs(other) do
        self[#self+1] = v
    end
    return self
end

When I want to share my own module in a single file I have to copy and paste these codes. I think OpenResty should add a standard `lua-resty-xxx` module providing such base functions as python or ruby does.

It will encourage high level module creation of OpenResty and let us write less code when in prototype development.

rpaprocki

Hi,

On Sun, Aug 7, 2016 at 6:51 PM, 项楠 <xiang...@gmail.com> wrote:

When I want to share my own module in a single file I have to copy and paste these codes. I think OpenResty should add a standard `lua-resty-xxx` module providing such base functions as python or ruby does.
It will encourage high level module creation of OpenResty and let us write less code when in prototype development.

Well, it seems like you could just create your own github project and share it with the community. You could add it to bungle's awesome-resty list (https://github.com/bungle/awesome-resty) and share updates here on this list. And for your own prototyping, why not just make a local module that provides these functions, so you only have to require one thing?

That being said, I don't think such prototyping is always effective. Obscuring very very small chunks of code like that can be unhealthy (sacrificing prototyping time for a better understanding of the platform is a negative, but I doubt everyone agrees with me there ;) ), and in certain cases it's had disastrous consequences on the ecosystem (lookin at you, left-pad).

This also brings up the question of what's "standard". Certainly stylistic homogeneity has never really been a core focus, with some of the most popular resty modules being written by different authors, all having different styles. There's no codified standard (and I'd argue there shouldn't be), only best practices; besides, who's to determine what becomes "standard"? When does adding more and more convenience functions simply become bloat?

aapo.talvensaari

On Monday, 8 August 2016 19:04:48 UTC+3, rpaprocki wrote:

That being said, I don't think such prototyping is always effective.

I agree. No need to have this in core. There are these btw (not sure if they are same):

http://stevedonovan.github.io/Penlight/api/index.html

http://stevedonovan.github.io/microlight/

https://github.com/Yonaba/Moses

https://github.com/jtarchie/underscore-lua

https://github.com/Yonaba/30log

https://github.com/kikito/middleclass

https://github.com/jpatte/yaci.lua

In general, I wish most of the lua-resty-* libs have as little dependencies as they could. Being self-contained has its own benefits.

Copy-pasting 10 to 30 lines of code is not bad when you can avoid a dependency by doing that (especially this simple). Copy pasting hundreds of lines of code is a bad thing (usually), and having a dependency is a good thing. Again, I'm sure some people may think the other way around.