Intel® Quartus® Prime Standard Edition User Guide: Scripting

ID 683325
Date 9/24/2018
Document Table of Contents Nested Command Substitution

Nested command substitution refers to how the Tcl interpreter evaluates Tcl code in square brackets. The Tcl interpreter evaluates nested commands, starting with the innermost nested command, and commands nested at the same level from left to right. Each nested command result is substituted in the outer command.
set a [string length foo]