self & parent

Keywords that navigate the enclosing scope — self is the current block, parent the one around it.

Inside a block, the self and parent keywords are navigators into the document — the same kind of lazy reference a &T field holds. self resolves to the current block (the innermost enclosing scope); parent resolves to the block around it. Both walk the lexical scope chain upward, so a field can read a sibling or an ancestor without naming the whole path.

§ 1self

self names the current block. Member access off it reads a field declared in the same block — handy when a name would otherwise be shadowed, or to be explicit about where a value comes from.

box "panel" {
  width  = 480.0
  height = 270.0
  // self.width reads this block's own `width` field.
  ratio  = self.width / self.height
}

§ 2parent

parent names the enclosing block one level out. Use it to read a value declared on the container from within a nested block. Referencing parent at the document root is an error — there is no scope above it.

service "web" {
  region = "us-east-1"
  metadata {
    // parent.region reaches the surrounding service block.
    inherited_region = parent.region
  }
}