Modifying Lua Functions

Question

I am trying to mod a Lua game (CtGW). There is a function, engine:GetSavegames, which returns an array of strings, and I cannot access. I need to modify the returned results. I tried the following, but recieved a "function arguments expected near 'engine'" error.

getsaves = engine:GetSavegames
engine:GetSavegames = function()
 return getsaves()
end

One thing you could try is engine.GetSavegames = ..., that would fix the syntax. Whether this will actually work and do what you want depends on how the rest of the stuff is coded. — Chris Beck
– Chris Beck, Commented Nov 12, 2015 at 4:13

Community · Accepted Answer · 2017-05-23 11:59:02Z

3

engine:GetSavegames is only valid syntax for method invocation and not for assignments. As @ChrisBeck wrote in the comment, you need to use engine.GetSavegame, but you also need to pass any parameters you can get as those will include the actual object.

Something like this may work:

local getsaves = engine.GetSavegames
engine.GetSavegames = function(...)
  return getsaves(...)
end

This operation is usually called monkeypatching.

edited May 23, 2017 at 11:59

CommunityBot

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answered Nov 12, 2015 at 6:43

Paul Kulchenko

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3 Comments

Daniel Herr Over a year ago

Thanks, this worked on the Lua demo page. But I don't think there are any parameters possible.

Paul Kulchenko Over a year ago

If it's called as engine:GetSavegames, there is going to be at least one parameter as this is equivalent to engine.getSavegames(engine), so the code needs to account for that.

Daniel Herr Over a year ago

Thanks again, I did need to add that, and have it working now.

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