What is a namespace in Tcl?
WHAT IS A NAMESPACE? A namespace is a collection of commands and variables. It encapsulates the commands and variables to ensure that they won’t interfere with the commands and variables of other namespaces. Tcl has always had one such collection, which we refer to as the global namespace.
What is namespace eval in Tcl?
Tcl has always had one such collection, which we refer to as the global namespace. The global namespace holds all global variables and commands. The namespace eval command lets you create new namespaces. For example, namespace eval Counter { namespace export Bump variable num 0 proc Bump {} { variable num incr num } }
What is the meaning of :: in Tcl?
Since in a Tcl script any top-level construct is always a command, and the command’s name is always the first word of the command, your report::TimeStamp refers to a command named “TimeStamp” in a namespace named “report” while “PrePlace” and “START PrePlace” are two arguments passed to that command when it’s invoked.
What is the command to list all existing procedure in Tcl?
DESCRIPTION. The proc command creates a new Tcl procedure named name, replacing any existing command or procedure there may have been by that name. Whenever the new command is invoked, the contents of body will be executed by the Tcl interpreter.
What is variable Tcl?
Variables. Variables in tcl can be defined with the command set and the value can be used with $variable_name . Arrays can be indexed with arbitrary names in (). Curly braces are used to separate variable names from following characters.
What is a namespace in computer science?
A namespace is a declarative region that provides a scope to the identifiers (the names of types, functions, variables, etc) inside it. Namespaces are used to organize code into logical groups and to prevent name collisions that can occur especially when your code base includes multiple libraries.
What does eval do in Tcl?
Eval concatenates all its arguments in the same fashion as the concat command, passes the concatenated string to the Tcl interpreter recursively, and returns the result of that evaluation (or any error generated by it).
How does Tcl work?
Tcl works by processing commands. In this regard, it’s similar to an operating system shell like DOS or bash. Each line of a Tcl script is a command, and the first word of each line is the name of the command, and any other words are arguments for the command.
How do I add elements to a list in Tcl?
lset varName index newValue. The lset command can be used to set elements of a list directly, instead of using lreplace . Lists in Tcl are the right data structure to use when you have an arbitrary number of things, and you’d like to access them according to their order in the list. In C, you would use an array.
What is lindex in Tcl?
lindex , a built-in Tcl command, retrieves an element from a list or a nested list.
How do I use variables in Tcl script?
Variables in tcl can be defined with the command set and the value can be used with $variable_name . Arrays can be indexed with arbitrary names in (). Curly braces are used to separate variable names from following characters.