[15.25]math.random non deterministic

[Choumiko]

Luas math.random seems to be non deterministic depending on how you call it inside your scripts:

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local math = math
local random = math.random

local random1 = function()
    game.print(random())
end

local random2 = function()
    game.print(math.random())
end

commands.add_command("test_random1", "", random1)
commands.add_command("test_random2", "", random2)

/test_random1 desyncs every time, whereas test_random2 never desyncs

Related mod bug report + commit that solved it: https://github.com/Choumiko/FARL/issues/85

Mod to reproduce the desync attached

[darkfrei]

What difference between

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local random = math.random

and

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local random = math.random()

[Nexarius]

math.random is just a variable (variables can be functions)
math.random() is calling the function with the name math.random

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local random = math.random

The variable random is set to math.random

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local random = math.random()

The variable random is set to the result of the function math.random

[Rseding91]

Thanks for the report. This was due to the order that we replace math.random with our own deterministic random generator. The control.lua contents are parsed first then we replaced math.random. I changed it for the next version of 0.15 so it replaces math.random first then parses the script so both functions will get a reference to our built in deterministic random generator.

It's fixed now for the next version of 0.15.