Re: local _META = {string = {__index = function(s, k) if type(k) == "number" then return string.sub(s, k, k) end return string[k] end}}

[Dirk Laurie <dirk.laurie@...>]

2014-12-09 20:35 GMT+02:00 Thiago L. <fakedme@gmail.com>:
>
> On 09/12/14 04:05 PM, Dirk Laurie wrote:
>>
>> 2014-12-09 19:43 GMT+02:00 Thiago L. <fakedme@gmail.com>:
>>>
>>> On 09/12/14 03:46 AM, Dirk Laurie wrote:
>>>>
>>>> 2014-12-08 21:48 GMT+02:00 Thiago L. <fakedme@gmail.com>:
>>>>>
>>>>> On 08/12/14 05:47 PM, Thiago L. wrote:
>>>>>>
>>>>>>
>>>>>> On 08/12/14 02:15 PM, Dirk Laurie wrote:
>>>>>>>
>>>>>>> Do you expect the relationship
>>>>>>>       `_ENV.string == getmetatable"".__index`
>>>>>>> to survive?
>>>>>>>
>>>>>> local _ENV = {string = {}}
>>>>>> print(_ENV.string == getmetatable"".__index) --> false
>>>>>>
>>>>> Wait actually I'm not sure what you're asking...?
>>>>
>>>> Do you want string.sub(str,i,j) and str:sub(i,j) to do the
>>>> same (as it now does) after you have assigned something
>>>> to _META.string?
>>>>
>>> I want to be able to tweak it as needed (aka if I change the string table
>>> I
>>> wanna be able to change the string metatable to do the same as the string
>>> table _BUT_ only inside the sandboxed environment)
>>>
>>> So technically, considering I can _ENV.string = {}, it doesn't actually
>>> do
>>> the same does it?
>>
>> Since string is the only type that works this way, maybe just coding it
>> in plain Lua is readable enough.
>>
>> _META = getmetatable""
>> _INDEX = {sub = function(s, i, j) return "nope" end}
>>
>> s = "test"
>> print(s:sub(1,2))
>>
>> do
>>     local string = _INDEX
>>    _META.__index = string
>>     print(s:sub(1,2),string.sub(s,1,2))
>> end
>>
>> _META.__index = string
>> print(s:sub(1,2))
>>
> function f(s)
>   return s:sub(1,2)
> end
>
> _META = getmetatable""
> _INDEX = {sub = function(s, i, j) return "nope" end}
>
> s = "test"
> print(s:sub(1,2))
>
> do
>    local string = _INDEX
>   _META.__index = string
>    print(f(s)) --> prints "nope", with my proposal it would print "te"
> end

I can't do that unless you grant me the use of debug.setmetatable.