What does uplevel do?
Description. uplevel concatenates the arg arguments, in the same manner as concat, into a single script, changes the current level to $level, evaluates the script, and returns the result. If level is positive integer, uplevel evaluates the script that many levels up from the current level.
What is uplevel in Tcl?
Uplevel returns the result of that evaluation. If level is an integer then it gives a distance (up the procedure calling stack) to move before executing the command. If level consists of # followed by a number then the number gives an absolute level number. If level is omitted then it defaults to 1.
What is Upvar and uplevel in Tcl?
The Tcl upvar [ upvar manual] and uplevel [ uplevel manual] commands allow a procedure to modify the local variables of any procedure on the call stack. They are very powerful, and it is easy to use them to create code that is very hard to understand and maintain.
What is EVAL command 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 can I uplevel my life?
How To Uplevel Your Life
- Mindset. Improve the way you talk to yourself.
- Values. Identify your top five values and what they mean to you.
- Vision. Write down your vision for the future and what you would like to achieve.
- Habits. Commit to habits that align with your values and vision.
- Actions & Decisions.
What is namespace in Tcl?
Namespace is a container for set of identifiers that is used to group variables and procedures. Namespaces are available from Tcl version 8.0. Before the introduction of the namespaces, there was single global scope. Now with namespaces, we have additional partitions of global scope.
What is source in Tcl?
DESCRIPTION. This command takes the contents of the specified file or resource and passes it to the Tcl interpreter as a text script. The return value from source is the return value of the last command executed in the script.
What is variable TCL?
The name of variables can contain any characters and length. You can even have white spaces by enclosing the variable in curly braces, but it is not preferred. The set command is used for assigning value to a variable. The syntax for set command is, set variableName value. A few examples of variables are shown below −
How do you declare global variables in TCL?
The global command will cause a variable in a local scope (inside a procedure) to refer to the global variable of that name. The upvar command is similar. It “ties” the name of a variable in the current scope to a variable in a different scope. This is commonly used to simulate pass-by-reference to procs.
What is Subst in Tcl?
subst , a built-in Tcl command, substitutes variables commands, and backslash sequences in a string.
Is up level a word?
Uplevel definition (computing) Having greater capabilities or a higher version number.
What is double colon in Tcl?
The double-colon ( :: ) is a namespace separator, and by analogy with the filesystem, if the name starts with the separator, it’s resolved with respect to the global namespace. For example, the global set command can equivalently be called as ::set . It will work identically.
What does the uplevel command do?
7 The uplevelcommand executes a command (or in fact a script) in another scope than that of the current procedure. In particular, in this case it is uplevel 1which means “execute in caller”. (You can also execute in the global scope with uplevel #0, or in other places too such as the caller’s caller with uplevel 2but that’s reallyrare.)
Uplevel makes it possible to implement new control constructs as Tcl procedures (for example, uplevel could be used to implement the while construct as a Tcl procedure). namespace eval is another way (besides procedure calls) that the Tcl naming context can change. It adds a call frame to the stack to represent the namespace context.
What is the use of uplevel call frame?
It adds a call frame to the stack to represent the namespace context. This means each namespace eval command counts as another call level for uplevel and upvar commands. For example, info level 1 will return a list describing a command that is either the outermost procedure call or the outermost namespace eval command.
What was the first practical use of uplevel 1?
3 1 In 8.6, we managed to find a use for uplevel #1with coroutines. This was considered to be the first practical use everfor that particular form, even though it has been legal for decades. – Donal Fellows