Script

The file

• Every file holds one script; the extension is .kalem, the encoding UTF-8.
• The script's name is PascalCase and the file's name its kebab-case form: BusinessHours ↔ business-hours.kalem. The compiler checks that they match.
• The script's id comes from the file name: kalem/business-hours. Components name the script by this id (Components).

The header

/// Opens and closes the business by its hours and the town's power.
server script BusinessHours extends Building
label "Business · opening hours"
category "Server behaviours"
version 2          // optional, 1 if omitted; used by migration

• server or client is required: a script runs either in the world or on screen.
• extends names the script's host type: where it can be attached and what it can use (Host types). The host type must be on the script's side: Building is a server type, VisualEffect a client type.
• A script extends exactly one host type; scripts do not extend each other.
• label and category title the script in the Add Component selector and on the component's card. The /// comment above the header is its description.
• version is 1 when omitted; raising it runs on migrate when a live world moves to the new definition (Saving and migration).

What the side allows

Declaration	Server	Client
property, group, function	yes	yes
memory, reads, writes, timer	yes	no
event handlers, state	yes	no
input	no	yes

Server code is never sent to the screen: the compiler puts only client scripts in the client's package.

Several scripts on one object

A package, a part or the world can take several scripts. Their order is the order of the components in the editor, and it also sets the order of work within a minute.

What a script declares

After the header, in any order:

Declaration	Page
property, group	Properties
memory	Memory and locals
reads, writes	Contract fields
on …	Events
timer	Timers
state, auto state	States
function	Functions and expressions
input	Client scripts