Content constants

An item, a liquid, a block and a unit are values like a number: they go into variables and get passed to instructions

easyYou need: Assignment and copying, Number, object and text

@copper is not a number and not a text. It is copper itself: the same item that sits in a container and rides a conveyor. The game creates such a constant for every thing it has.

What	How many	Examples
items	20	@copper, @silicon, @thorium
liquids	11	@water, @slag, @cryofluid
blocks	262	@router, @vault, @duo, @air
unit types	56	@poly, @mono, @flare

Names are written the way the thing is called in the game, in English and with hyphens: @surge-alloy, @phase-fabric, @titanium-conveyor.

They go into variables

Press “step” five times.

steptick 0

Set0

=

Set1

=

Set2

=

Set3

=

Sensor4

=

 in

@counter0number

itemnullnull

blocknullnull

unitnullnull

selfnullnull

amountnullnull

In the table item, block and unit have the type content — not a number, not a text, but a thing. No arithmetic comes of them: copper cannot be added to a router, but they can be passed where a thing is expected.

Where that comes in handy:

• sensor — ask a container how much copper it holds;
• control config — set a sorter to the item you want;
• ubind — take control of a unit of the right type;
• draw image — draw a thing’s icon on a display.

Note

With set the thing’s name is typed by hand: there are two fields and both are simple. But sensor, ubind and draw image have a pencil next to the field, and it opens a table of every item, liquid, block and unit — which is also the quickest way to check how a name is spelt.

One name, two roles

The example’s last line is sensor amount container1 item, and item holds @copper. The answer: 120, the amount of copper in the container.

This is worth pausing on. @copper in the property field means “how much copper”, and @copper in the value field means “copper itself”. The name is one, and the role depends on where it was put — and that is not confusion but how the language is built: sensor looks at what it was handed and answers differently to a thing and to a property like @health.

To sensor there is no difference between @copper typed straight into the field and @copper arriving from a variable. So items can be walked through the same way: put them into a memory cell and ask about them in turn.

@this and its neighbours

A separate little pile of constants is about the processor itself:

Name	What it is
@this	the processor’s own building, of type building
@thisx, @thisy	its coordinates in tiles, numbers
@links	how many links it has
@ipt	how many instructions it runs per tick

@this is a building, like container1: you can ask it for properties and pass it where a block is expected. In the example it sits in the variable self, and the table shows the processor’s name.

Silent failure

Constants are read-only, and the variables table does not show them at all — neither @copper nor @this. The variables window shows what changes; what does not change lives in a separate list, opened by the “Built-in variables” button.

When a name is not enough

Sometimes an item is needed by index rather than by name: to walk all twenty without writing each one out. There is a separate instruction for that — lookup — which fetches a thing by its index in the game.

Remember

• @copper, @router, @poly are thing-values: items, liquids, blocks and unit types.
• In the table their type is content, and arithmetic does not work on them.
• They go into variables and get passed to instructions that expect a thing.
• The same name can be both a value and a property — the field decides the role.
• @this is the processor’s own building, @thisx and @thisy its coordinates.

Task

Replace @copper in the first line with @lead and run the example again: amount becomes forty, because that is how much lead is in the container. The name has to be typed by hand — set has no pencil, but the last line, with sensor, does.

Then type @totalItems into the last line instead of item. That is no longer a thing but a property, and the answer becomes 160 — all the container’s items together.