Variables and functions

Variables

A variable holds a value under a name, so you can set it once and use it in many places, and change the script by changing one block.

1. Open variables in the toolbox and press Create variable....
2. Type its name and press Create.
3. The category now holds its blocks: set … to gives it a value, change … by adds to it, and the block with its name reads it wherever a value is needed.

Stack the set block above the blocks that read the variable, since blocks run from top to bottom. A parametric cube sizes a solid this way, step by step.

Functions

A function wraps a stack of blocks under a name, so you can run it from several places.

• to do something holds blocks that do something; name it by clicking its title.
• to do something … return also gives a value back, plugged into its return input.

Once defined, a function's own block appears in the functions category: use it like any other block. A function can take inputs too: the gear on its definition adds them.

Functions that wait

A block that makes geometry, such as a cylinder, gives its shape a moment later, and any bitbybit block it goes into waits for it. So a function can make shapes, pass them on and return them without waiting itself: the block that receives its result waits for that too.

When the blocks need the value itself, to compute with a shape's centre or count the faces of a solid, put an await block in the set block that keeps it. A function with an await block in it runs as async:

• a call of it as a block of its own waits for it to finish before the next block runs;
• a set block that keeps what it returns waits for it too, so the blocks after it get the value itself;
• plugged anywhere else, its call gives the value a moment later, and the bitbybit block it goes into waits for it, like any shape;
• a function that calls it is async too.

Variables are shared by the whole script, so keep an async function's result with a set block. Then nothing runs while the function waits, and nothing changes the variables it is using.

The drone sorts its lights by side this way: a function awaits each light's centre and keeps the ones on the side it is asked for.

Right-click a function and choose Collapse Block to fold it to one line once it works; a large script reads best with its functions collapsed and its main stacks open.