Re: Noob's attempt at Lua
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- Subject: Re: Noob's attempt at Lua
- From: Sean Conner <sean@...>
- Date: 2022年4月23日 19:05:31 -0400
It was thus said that the Great siiky once stated:
> Hi there, list o/
Hello.
> But there's the problem (for me at least): can a table be callable?
> Would that be possible to do?
Yes, it's easy to do with the __call metamethod. An example:
mt = { __call = function(self,x) return x end }
t = {}
setmetatable(t,mt)
print(t(3))
> 2. The server's replies are almost all in JSON. Is it worth it to make
> the parser parameterized such that a user of the library may use any one
> they like? For whatever reason -- it could be performance, less deps,
> &c. It should be really easy to implement, it's just one extra instance
> parameter.
This might be quite involved, as I counted 45 JSON modules in LuaRocks
alone. Just looking at three of them:
dkjson defines the following:
json.decode(string,position,nullvalue,mt)
string - data to decode
position - starting position, 1 if not given
nullvalue - value to use for JSON null , nil if not given
mt - returned data has metatable if not nil
org.conman.parsers.json (and org.conman.parsers.jsons) defines:
json:match(string,position)
string - data to decode
position - starting position, 1 if not given
and to set a custom null value, a global variable 'null' can be defined.
json-lua defines:
JSON:decode(string)
with no way to specify a value for JSON's null.
> 3. If you'd like to spend some of your precious time to educate a
> noob, could you take a quick look at the code and see if there are any
> glaring points to improve? :)
Only one thing came to mind: string.format("%q",s) will return some
characters escaped (see the manual for more information).
-spc