From: Paul Lutus <nospam@...>
Date: 2006-09-07T00:40:16+09:00
Subject: Re: concurrent input from GUI *and * from irb

Joachim (M端nchen) wrote:

> my user should be able to define variables, to define functions, to
> include scripts, to hack for-loops, to iterate over arrays &c: the full
> functionality of irb. Is that really possible with Kernel::eval ?

A lot of user-entered code can be packed into an "eval" entry and then
executed. A simple example:

#/usr/bin/ruby -w

eval("1.upto(12) { |y| 1.upto(12) { |x| printf(\"%4d\",x*y) }; puts \"\" }")

Output:

   1   2   3   4   5   6   7   8   9  10  11  12
   2   4   6   8  10  12  14  16  18  20  22  24
   3   6   9  12  15  18  21  24  27  30  33  36
   4   8  12  16  20  24  28  32  36  40  44  48
   5  10  15  20  25  30  35  40  45  50  55  60
   6  12  18  24  30  36  42  48  54  60  66  72
   7  14  21  28  35  42  49  56  63  70  77  84
   8  16  24  32  40  48  56  64  72  80  88  96
   9  18  27  36  45  54  63  72  81  90  99 108
  10  20  30  40  50  60  70  80  90 100 110 120
  11  22  33  44  55  66  77  88  99 110 121 132
  12  24  36  48  60  72  84  96 108 120 132 144

It is difficult to imagine an advantage to irb in this context, where the
real source of the code is, say, a GUI text editor pane, and irb's keyboard
interaction preference may be difficult to overcome.

-- 
Paul Lutus
http://www.arachnoid.com