%onprompt special custom function called after each line execution in console

## Description

If it is defined, the function `%onprompt()`

- must be written in Scilab language.
- expects no explicit input argument.
- assigns to `ans` its first explicit output argument (if any).

Then, `%onprompt()` is automatically executed after the historization and the execution of each row of instructions entered in the console (even if it is only a comment).

If an output argument is defined, `ans` is displayed even if a semi-colon is appended to the row of instructions. Other explicit output arguments (if any) are ignored.

- `%onprompt()` may be (re)defined at any execution level.
- If some diaries are open and `%onprompt()` displays some contents in the console, these ones are recorded in the diaries with all other console outputs.

## Examples

    // Redisplaying the last line of instructions after its execution:
    function %onprompt()
        mprintf("%s\n", gethistory()($));
    endfunction
    a = grand(3,5,"uin",-9,9), b = %pi;
    // This is a comment

    --> a = grand(3,5,"uin",-9,9), b = %pi
     a  =
       0.  -5.  -9.   5.   3.
      -9.   5.  -9.  -4.   8.
       2.  -5.  -6.   6.   0.

     b  =
       3.1415927

    a = grand(3,5,"uin",-9,9), b = %pi

    --> // This is a comment
    // This is a comment

    -->

## See also

- prompt
- ans
- gethistory
- startup files