Lua http socket evaluation

I use lua 5.1 and the luaSocket 2.0.2-4 to retrieve a page from a web server. I first check if the server is responding and then assign the web server response to lua variables.

local mysocket = require("socket.http")
if mysocket.request(URL) == nil then
    print('The server is unreachable on:\n'..URL)
    return
end
local response, httpCode, header = mysocket.request(URL)

Everything works as expected but the request is executed two times. I wonder if I could do Something like (which doesn't work obviously):

local mysocket = require("socket.http")
if (local response, httpCode, header = mysocket.request(URL)) == nil then
    print('The server is unreachable on:\n'..URL)
   开发者_Python百科 return
end

---

Yes, something like this :

local mysocket = require("socket.http")
local response, httpCode, header = mysocket.request(URL)

if response == nil then
    print('The server is unreachable on:\n'..URL)
    return
end

-- here you do your stuff that's supposed to happen when request worked

Request will be sent only once, and function will exit if it failed.

---

Even better, when request fails, the second return is the reason:

In case of failure, the function returns nil followed by an error message.

(From the documentation for http.request)

So you can print the problem straight from the socket's mouth:

local http = require("socket.http")
local response, httpCode, header = http.request(URL)

if response == nil then
    -- the httpCode variable contains the error message instead
    print(httpCode)
    return
end

-- here you do your stuff that's supposed to happen when request worked