FreeMat: RETALL Return From All Keyboard Sessions

FreeMat

- Main Page
- Related Pages

RETALL Return From All Keyboard Sessions

Section: Flow Control

# Usage

The `retall` statement is used to return to the base workspace from a nested `keyboard` session. It is equivalent to forcing execution to return to the main prompt, regardless of the level of nesting of `keyboard` sessions, or which functions are running. The syntax is simple

       retall

The `retall` is a convenient way to stop debugging. In the process of debugging a complex program or set of functions, you may find yourself 5 function calls down into the program only to discover the problem. After fixing it, issueing a `retall` effectively forces FreeMat to exit your program and return to the interactive prompt.

# Example

Here we demonstrate an extreme example of `retall`. We are debugging a recursive function `self` to calculate the sum of the first N integers. When the function is called, a `keyboard` session is initiated after the function has called itself N times. At this `keyboard` prompt, we issue another call to `self` and get another `keyboard` prompt, this time with a depth of 2. A `retall` statement returns us to the top level without executing the remainder of either the first or second call to `self`:

         self.m

    function y = self(n)
      if (n>1)
        y = n + self(n-1);
        printf('y is %d\n',y);
      else
        y = 1;
        printf('y is initialized to one\n');
        keyboard
      end

    --> self(4)
    y is initialized to one
    [self,8]--> self(6)
    y is initialized to one
    [self,8]--> retall