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423 lines
6.7 KiB
Markdown
423 lines
6.7 KiB
Markdown
<!--
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#
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# Licensed to the Apache Software Foundation (ASF) under one or more
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# contributor license agreements. See the NOTICE file distributed with
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# this work for additional information regarding copyright ownership.
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# The ASF licenses this file to You under the Apache License, Version 2.0
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# (the "License"); you may not use this file except in compliance with
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# the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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-->
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[Chinese](CODE_STYLE_CN.md)
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# APISIX Lua Coding Style Guide
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## indentation
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Use 4 spaces as an indent:
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```lua
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--No
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if a then
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ngx.say("hello")
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end
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```
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```lua
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--Yes
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if a then
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ngx.say("hello")
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end
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```
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You can simplify the operation by changing the tab to 4 spaces in the editor you are using.
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## Space
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On both sides of the operator, you need to use a space to separate:
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```lua
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--No
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local i=1
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local s = "apisix"
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```
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```lua
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--Yes
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local i = 1
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local s = "apisix"
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```
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## Blank line
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Many developers will add a semicolon at the end of the line:
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```lua
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--No
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if a then
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ngx.say("hello");
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end;
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```
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Adding a semicolon will make the Lua code look ugly and unnecessary. Also, don't want to save the number of lines in the code, the latter turns the multi-line code into one line in order to appear "simple". This will not know when the positioning error is in the end of the code:
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```lua
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--No
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if a then ngx.say("hello") end
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```
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```lua
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--Yes
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if a then
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ngx.say("hello")
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end
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```
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The functions needs to be separated by two blank lines:
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```lua
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--No
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local function foo()
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end
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local function bar()
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end
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```
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```lua
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--Yes
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local function foo()
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end
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local function bar()
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end
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```
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If there are multiple if elseif branches, they need a blank line to separate them:
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```lua
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--No
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if a == 1 then
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foo()
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elseif a== 2 then
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bar()
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elseif a == 3 then
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run()
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else
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error()
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end
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```
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```lua
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--Yes
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if a == 1 then
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foo()
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elseif a== 2 then
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bar()
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elseif a == 3 then
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run()
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else
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error()
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end
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```
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## Maximum length per line
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Each line cannot exceed 100 characters. If it exceeds, you need to wrap and align:
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```lua
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--No
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return limit_conn_new("plugin-limit-conn", conf.conn, conf.burst, conf.default_conn_delay)
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```
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```lua
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--Yes
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return limit_conn_new("plugin-limit-conn", conf.conn, conf.burst,
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conf.default_conn_delay)
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```
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When the linefeed is aligned, the correspondence between the upper and lower lines should be reflected. For the example above, the parameters of the second line of functions are to the right of the left parenthesis of the first line.
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If it is a string stitching alignment, you need to put `..` in the next line:
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```lua
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--No
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return limit_conn_new("plugin-limit-conn" .. "plugin-limit-conn" ..
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"plugin-limit-conn")
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```
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```lua
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--Yes
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return limit_conn_new("plugin-limit-conn" .. "plugin-limit-conn"
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.. "plugin-limit-conn")
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```
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```lua
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--Yes
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return "param1", "plugin-limit-conn"
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.. "plugin-limit-conn"
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```
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## Variable
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Local variables should always be used, not global variables:
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```lua
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--No
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i = 1
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s = "apisix"
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```
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```lua
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--Yes
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local i = 1
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local s = "apisix"
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```
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Variable naming uses the `snake_case` style:
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```lua
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--No
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local IndexArr = 1
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local str_Name = "apisix"
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```
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```lua
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--Yes
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local index_arr = 1
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local str_name = "apisix"
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```
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Use all capitalization for constants:
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```lua
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--No
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local max_int = 65535
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local server_name = "apisix"
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```
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```lua
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--Yes
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local MAX_INT = 65535
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local SERVER_NAME = "apisix"
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```
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## Table
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Use `table.new` to pre-allocate the table:
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```lua
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--No
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local t = {}
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for i = 1, 100 do
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t[i] = i
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end
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```
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```lua
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--Yes
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local new_tab = require "table.new"
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local t = new_tab(100, 0)
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for i = 1, 100 do
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t[i] = i
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end
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```
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Don't use `nil` in an array:
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```lua
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--No
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local t = {1, 2, nil, 3}
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```
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If you must use null values, use `ngx.null` to indicate:
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```lua
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--Yes
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local t = {1, 2, ngx.null, 3}
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```
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## String
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Do not splicing strings on the hot code path:
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```lua
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--No
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local s = ""
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for i = 1, 100000 do
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s = s .. "a"
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end
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```
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```lua
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--Yes
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local new_tab = require "table.new"
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local t = new_tab(100, 0)
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for i = 1, 100000 do
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t[i] = "a"
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end
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local s = table.concat(t, "")
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```
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## Function
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The naming of functions also follows `snake_case`:
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```lua
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--No
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local function testNginx()
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end
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```
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```lua
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--Yes
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local function test_nginx()
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end
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```
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The function should return as early as possible:
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```lua
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--No
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local function check(age, name)
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local ret = true
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if age < 20 then
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ret = false
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end
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if name == "a" then
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ret = false
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end
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-- do something else
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return ret
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end
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```
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```lua
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--Yes
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local function check(age, name)
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if age < 20 then
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return false
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end
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if name == "a" then
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return false
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end
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-- do something else
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return true
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end
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```
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## Module
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All require libraries must be localized:
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```lua
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--No
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local function foo()
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local ok, err = ngx.timer.at(delay, handler)
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end
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```
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```lua
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--Yes
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local timer_at = ngx.timer.at
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local function foo()
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local ok, err = timer_at(delay, handler)
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end
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```
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For style unification, `require` and `ngx` also need to be localized:
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```lua
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--No
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local core = require("apisix.core")
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local timer_at = ngx.timer.at
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local function foo()
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local ok, err = timer_at(delay, handler)
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end
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```
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```lua
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--Yes
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local ngx = ngx
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local require = require
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local core = require("apisix.core")
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local timer_at = ngx.timer.at
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local function foo()
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local ok, err = timer_at(delay, handler)
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end
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```
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## Error handling
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For functions that return with error information, the error information must be judged and processed:
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```lua
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--No
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local sock = ngx.socket.tcp()
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local ok = sock:connect("www.google.com", 80)
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ngx.say("successfully connected to google!")
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```
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```lua
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--Yes
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local sock = ngx.socket.tcp()
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local ok, err = sock:connect("www.google.com", 80)
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if not ok then
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ngx.say("failed to connect to google: ", err)
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return
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end
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ngx.say("successfully connected to google!")
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```
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The function you wrote yourself, the error message is to be returned as a second parameter in the form of a string:
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```lua
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--No
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local function foo()
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local ok, err = func()
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if not ok then
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return false
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end
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return true
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end
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```
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```lua
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--No
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local function foo()
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local ok, err = func()
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if not ok then
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return false, {msg = err}
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end
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return true
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end
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```
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```lua
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--Yes
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local function foo()
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local ok, err = func()
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if not ok then
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return false, "failed to call func(): " .. err
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end
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return true
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end
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```
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