Editing Module:Buffer/doc (section)

====Buffer:_R====
{{luaself|:_R|args=name, save|args2='new_G', var, metaindex}}

This {{luaref|rawset||y}} with the global table as the first argument and <code>name</code> and <code>save</code> as the second and third, respectively, returning the Buffer object for call chaining.<ref group="example">The following demonstrates how, by combining Buffer:_R and Buffer:_G, the global variable ''v'' can be declared, backed-up and replaced, replaced without back-up, restored from back-up, and removed completely:
:{|
|{{#tag:syntaxhighlight|require'Module:Buffer'
   (_G,'v')           -- call module with global functions enabled and declare new buffer as v
   :_'A'              -- append 'A' to the returned buffer
   :_G('v', 1):_(v)   -- _G.v = 1, shift old value (the buffer) to metaglobal.__index
   :_R('v', 2):_(v)   -- _G.v = 2, discard old value (1) without back-up
   :_R'v':_(v)        -- unset _G.v, which now defaults to metaglobal.__index.v (the buffer)
   :_G('v', nil)", "  -- remove back-up and join the buffer with a separator
..' and '..tostring(v)-- returns 'A, 1, 2, A12 and nil'|lang=lua}}
|}</ref> This is a no-op if ''name'' is nil or a boolean.

{{anchor|new_G}}
{{see|#new_G object}}
Note that Buffer methods use a local variable <code>new_G</code> as a proxy for the global table _G; though not a global index, the string {{code|lang=lua|'new_G'}} is a "magic word" that changes the destination for future ''save'' for this and Buffer:_G.

Pass a table as <code>var</code> (same place as ''save'') to set as the ''new'' new_G. Any table such that {{code|lang=lua|1=var._G == _G}} is treated as a (former) new_G object. This {{luaref|getmetatable|gets the metatable|y}} of former proxies and {{luaref|setmetatable|sets a new table|y}} with the {{luaself|_G object|plain=y}} __call method on non-new_G tables. Then, this, if third parameter <code>metaindex</code> equals:
* nil {{--}} backs up the current proxy as the metaindex of the next (though this no-ops if ''var'' equals new_G to avoid cyclical indexing).
* false {{--}} leaves the metaindex intact (replacing the current proxy without back-up)
* true {{--}} unsets the metaindex of the next proxy
* any other value {{--}} sets that value as the metaindex of the next proxy. (Note new_G._G is not set until it is returned by {{luaself|:_2}})

To omit or to pass nil/false as ''var'' has the same effect as {{luaself|:_R|args='new_G', {} }}. Pass true instead and this treats it as though passed as ''metaindex'', creating a new proxy without backing up the incumbent.