Dynamic prerequisites

[PyroGamer666]

I am currently developing a mod with a tech tree that precedes the vanilla tech tree. The last technology in my tech tree, with the internal name "iron-axe", should be the prerequisite to all technologies that normally do not have any prerequisites. In order to accomplish this, I wrote the following code before adding my mod's technologies to data in the same file.

Code: Select all

for key,tech in ipairs(table.deepcopy(data.raw["technology"])) do
    if tech.prerequisites==nil or tech.prerequisites=={} then
        tech.prerequisites={"iron-axe"}
        data:extend{tech}
    end
    
end

However, this code fails to add the prerequisite to any technologies. If someone knows how to fix this, I would like to know.

[Qon]

You shouldn't copy things you want to modify, then you are modifying a copy. And you don't extend things already in data. Since it's an update the code should be in data-updates.lua, I'm pretty sure. But maybe that's not necessary for modificatiosn to vanilla prototypes?

[DaveMcW]

Code: Select all

for key,tech in pairs(data.raw["technology"]) do
    if tech.prerequisites==nil or tech.prerequisites=={} then
        tech.prerequisites={"iron-axe"}
    end
end

If you are only modifying vanilla recipes you can use data.lua with a dependency on base.

[eradicator]

Code: Select all

tech.prerequisites=={} 

This does not do what you want, lua tables have identity

Code: Select all

> print({} == {})
false

You could try table_size()==0.

[PyroGamer666]

Code: Select all

for key,tech in pairs(data.raw["technology"]) do
    if tech.prerequisites==nil or tech.prerequisites=={} then
        tech.prerequisites={"iron-axe"}
    end
end

If you are only modifying vanilla recipes you can use data.lua with a dependency on base.

This code does exactly what I was trying to do, thank you.

[eradicator]

Code: Select all

for key,tech in pairs(data.raw["technology"]) do
    if tech.prerequisites==nil or tech.prerequisites=={} then
        tech.prerequisites={"iron-axe"}
    end
end

If you are only modifying vanilla recipes you can use data.lua with a dependency on base.

This code does exactly what I was trying to do, thank you.

No it doesn't tech.prerequisites=={} is *always false*.

[sparr]

Code: Select all

table.compare(tech.prerequisites,{})
#tech.prerequisites == 0
table_size(tech.prerequisites) == 0
...