Component API

The component API is used to access and interact with components available to a computer. Also see the page on component interaction.

• component.doc(address:string, method:string): string
  Returns the documentation string for the method with the specified name of the component with the specified address, if any. Note that you can also get this string by using tostring on a method in a proxy, for example tostring(component.screen.isOn).
• component.invoke(address:string, method:string[, ...]): ...
  Calls the method with the specified name on the component with the specified address, passing the remaining arguments as arguments to that method. Returns the result of the method call, i.e. the values returned by the method. Depending on the called method's implementation this may throw.
• component.list([filter:string[, exact:boolean]]):function
  Returns an iterator over all components currently attached to the computer, providing tuples of address and component type. Use it like so: for address, componentType in component.list() do ... end If filter is set this will only return components that contain the filter string (this is not a pattern/regular expression). For example, component.list("red") will return redstone components.
  If true is passed as a second parameter, exact matching is enforced, e.g. red will not match redstone.
• component.methods(address:string):table
  Returns a table with the names of all methods provided by the component with the specified address. The names are the keys in the table, the values indicate whether the method is called directly or not.
• component.proxy(address:string):table
  Gets a 'proxy' object for a component that provides all methods the component provides as fields, so they can be called more directly (instead of via invoke). This is what's used to generate 'primaries' of the individual component types, i.e. what you get via component.blah.
  For example, you can use it like so: component.proxy(component.list("redstone")()).getInput(sides.north), which gets you a proxy for the first redstone component returned by the component.list iterator, and then calls getInput on it.
  Note that proxies will always have at least two fields, type with the component's type name, and address with the component's address.
• component.type(address:string):string
  Get the component type of the component with the specified address.
• component.get(address: string[, componentType: string]): string | (nil, string)
  Tries to resolve an abbreviated address to a full address. Returns the full address on success, or nil and an error message otherwise. Optionally filters by component type.
• component.isAvailable(componentType: string): boolean
  Checks if there is a primary component of the specified component type.
• component.getPrimary(componentType: string): table
  Gets the proxy for the primary component of the specified type. Throws an error if there is no primary component of the specified type.
• component.setPrimary(componentType: string, address: string)
  Sets a new primary component for the specified component type. The address may be abbreviated, but must be valid if it is not nil. Triggers the component_unavailable and component_available signals if set to nil or a new value, respectively.
• component.list([filter: string]): function
  Returns an iterator which returns pairs of address, type for each component connected to the computer. It optionally takes a filter - if specified this will only return those components for which the filter is a substring of the component type. For example: lua local component = require("component") -- prints `redstone` for each attached redstone card. for _, name in component.list("red") do print(name) end

Note that the component API has a metatable that allows the following syntax:

snippet.lua

local component = require("component")
local rs0 = component.getPrimary("redstone")
local rs1 = component.redstone -- syntactic sugar
print(rs0 == rs1) -- true