[Pages 155-6]: When trouble strikes - Ruby debugger

Value: Low

Level: Easy

Summary:

The debugger supports the usual range of features you'd expect,
including the ability to set breakpoints, to step into and step over
method calls, and to display stack frames and variables, list the
instance methods defined for a particular object or class, list and
control separate threads within Ruby. If your Ruby installation has
readline support enabled, you can use cursor keys to move back and
forth in command history and use line-editing commands to amend
previous input.


Memo: None

Example:

# ruby -r debug [ debug-options ] [ programfile ] [ program-arguments ]

% ruby -r debug t.rb
Debug.rb
Emacs support available.
t.rb:1:def fact(n)
(rdb:1) list 1-9
[1, 10] in t.rb
=> 1 def fact(n)
2 if n <= 0
3 1
4 else
5 n * fact(n-1)
6 end
7 end
8
9 p fact(5)
(rdb:1) b 2
Set breakpoint 1 at t.rb:2
(rdb:1) c
breakpoint 1, fact at t.rb:2
t.rb:2: if n <= 0
(rdb:1) disp n
1: n = 5
(rdb:1) del 1
(rdb:1) watch n==1
Set watchpoint 2
(rdb:1) c
watchpoint 2, fact at t.rb:fact
t.rb:1:def fact(n)
1: n = 1
(rdb:1) where
--> #1 t.rb:1:in `fact'
#2 t.rb:5:in `fact'
#3 t.rb:5:in `fact'
#4 t.rb:5:in `fact'
#5 t.rb:5:in `fact'
#6 t.rb:9
(rdb:1) del 2
(rdb:1) c
120

Reported errata (at 10/17/06 14:17:18 PDT): 0

Errata I found: 0

My suggestions to the author: 0

Doubts: 0