ShapeScript programs are hierarchical, with { ... } braces used to denote the start and end of a block of related options or commands.
When you define symbols, the effect is limited to the scope of the current block, meaning that once the block exits (i.e. when the closing } is reached), and symbols defined inside it are discarded, and symbols whose values were overridden inside the block will revert to the value they had before the block was entered.
Block scope is not just limited to symbols; it also affects materials and transforms. When you use the translate, rotate and scale commands to modify the world-transform, or use color or texture to modify the current material, the effect of those changes is limited to the current block.
This is convenient, because it means that code that defines subcomponents in your scene can use transforms and materials internally without them “leaking out” and affecting other objects.
When you define a custom function, it also creates a local scope around its body. Like blocks, functions inherit symbols from their parent scope and locally defined symbols will not leak out into their parent scope. Unlike blocks, functions can affect the transforms and materials of the scope where they are invoked.
Control flow statements like for loops and if statements or switch cases also create local scopes around their bodies. Like function scope, loops and conditional scopes do not apply to transforms or materials, but only to symbols created using the define command.
Any symbols defined inside a for loop will be restricted to the inside of the loop body. This also applies to the optional loop index variable.