jecs/test/examples/luau/queries/wildcards.luau

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local jecs = require("@jecs")
local pair = jecs.pair
local world = jecs.World.new()
local Name = world:component()
local function named(ctr, name)
local e = ctr(world)
world:set(e, Name, name)
return e
end
local function name(e)
return world:get(e, Name)
end
local Eats = world:component()
local Apples = named(world.entity, "Apples")
local Oranges = named(world.entity, "Oranges")
local bob = named(world.entity, "Bob")
world:set(bob, pair(Eats, Apples), 10)
local alice = named(world.entity, "Alice")
world:set(alice, pair(Eats, Oranges), 5)
-- Aliasing the wildcard to symbols improves readability and ease of writing
local __ = jecs.Wildcard
-- Create a query that matches edible components
for entity, amount in world:query(pair(Eats, __)) do
-- Iterate the query
local food = world:target(entity, Eats)
print(`{name(entity)} eats {amount} {name(food)}`)
end
-- Output:
-- Alice eats 5 Oranges
-- Bob eats 10 Apples