Last modified: 2014-09-07 20:18:26 UTC
Create the following as Module:Foo: local p, mt = {}, {} function mt.__call(t, frame) return 'Hello from the __call metamethod' end p.main = setmetatable({}, mt) return p From the sandbox, =p.main(mw.getCurrentFrame()) correctly displays "Hello from the __call metamethod". From wikitext, however, {{#invoke:Foo|main}} displays a script error that p.main isn't a function.
What would be the advantage of allowing #invoke to call a table via the __call metamethod, instead of just using a function? Functions seem like they would be much less confusing to on-wiki module authors than tables-that-can-be-called.
Take this module, for example: local p = {} p.continents = { na = { area = 24490000, pop = 542056000 }, sa = { area = 17840000, pop = 392555000 }, antarctica = { area = 13720000, pop = 4490 } } p.oceans = { atlantic = { area = 82400000, volume = 323600000 }, pacific = { area = 165250000, volume = 714000000 } } local mt = {} function mt.__call(t, frame) for _,v in ipairs(frame.args) do t = t[v] end return t end for _,v in pairs(p) do setmetatable(v, mt) end return p This module allows other modules to retrieve data via "foo = p.continents.na.area", and wikitext to retrieve data via "{{#invoke:Foo|continents|na|area}}".
OTOH, you could as easily write that with a function getContinent, and at the same time avoid confusing people into thinking they could do "{{#invoke:Foo|bar|baz}}" for any random table that is included in 'p'. For that matter, returning random tables in 'p' may not be the greatest idea; see bug 48393 for example.
