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Today, I will talk to you about how to dynamically load modules in loadstring. Many people may not know much about it. In order to make you understand better, the editor has summarized the following content for you. I hope you can get something according to this article.

Let's first take a look at a snippet:

Do I = 32 local I = 0 f = loadstring ("I = I + 1; print (I)") g = function () I = I + 1; print (I) end f ()-- > 33 g ()-- > 1 h = function () _ G.I = _ G.I + 1; print (_ G.I) end h ()-- > 34end

F () output 33 g () output 1. The reason is that the first I is a global variable, the second I is a local variable, and the local variable of the same name always overrides the global variable. The functions generated by loadstring can only see global variables, so f () outputs 33. If you want the g () function to access the global variable I, you can take advantage of the global environment variable _ G, so h () returns 34.

So if you want to use loadstring to dynamically load Lua code from a string, you should not use the Lua global variable to hold the loaded Lua code chunk, but rather treat it as a Lua module. For example, the following example:

Local lua_src = [local _ M = {} local say = ngx.say function _ M.run () say ("hello world") end return _ M]] local f, err = loadstring (lua_src, "module foo") if not f then ngx.say ("failed to load module:", err) returnendlocal mod = f () if not mod then ngx.say ("Lua source does not return the module") returnendpackage.loaded.foo = mod

This is equivalent to loading a Lua module named foo directly from memory (a Lua string). Then whenever we want to call this piece of code, we can use it as if we were using a module:

Local foo = require "foo" foo.run () after reading the above, do you have any further understanding of how to dynamically load modules in loadstring? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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