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pry-stack_explorer

(C) John Mair (banisterfiend) 2011

Walk the stack in a Pry session

Please note, pry-stack_explorer has not been officially released yet and the prerelease gem that is available is NOT compatible with the current Pry gem (0.9.7.4). The prerelease gem only exists for testing purposes among Pry core committers. This gem will be fully available soon, when the next Pry version (0.9.8) is released.

pry-stack_explorer is a plugin for the Pry REPL that enables the user to navigate the call-stack.

From the point a Pry session is started, the user can move up the stack through parent frames, examine state, and even evaluate code.

Unlike ruby-debug, pry-stack_explorer incurs no runtime cost and enables navigation right up the call-stack to the birth of the program.

pry-stack_explorer is currently designed to work on MRI and Ruby 1.9.2+ (including 1.9.3). Support for other Ruby versions and implementations is planned for the future.

The up, down, frame and show-stack commands are provided.

Please note that this is a first release and may have some teething problems, feel free to file an issue if you encounter any problems.

Example: Moving around between frames

[8] pry(J)> show-stack

Showing all accessible frames in stack:
--
=> #0 [method]  c <Object#c()>
   #1 [block]   block in b <Object#b()>
   #2 [method]  b <Object#b()>
   #3 [method]  alphabet <Object#alphabet(y)>
   #4 [class]   <class:J> 
   #5 [block]   block in <main> 
   #6 [eval]    <main> 
   #7 [top]     <main> 
[9] pry(J)> frame 3

Frame number: 3/7
Frame type: method

From: /Users/john/ruby/projects/pry-stack_explorer/examples/example.rb @ line 10 in Object#alphabet:

     5: 
     6: require 'pry-stack_explorer'
     7: 
     8: def alphabet(y)
     9:   x = 20
 => 10:   b
    11: end
    12: 
    13: def b
    14:   x = 30
    15:   proc {
[10] pry(J)> x
=> 20

Example: Modifying state in a caller

Frame number: 0/3
Frame type: method

From: /Users/john/ruby/projects/pry-stack_explorer/examples/example2.rb @ line 15 in Object#beta:

    10:   beta
    11:   puts x
    12: end
    13: 
    14: def beta
 => 15:   binding.pry
    16: end
    17: 
    18: alpha
[1] pry(main)> show-stack

Showing all accessible frames in stack:
--
=> #0 [method]  beta <Object#beta()>
   #1 [method]  alpha <Object#alpha()>
   #2 [eval]    <main> 
   #3 [top]     <main> 
[2] pry(main)> up

Frame number: 1/3
Frame type: method

From: /Users/john/ruby/projects/pry-stack_explorer/examples/example2.rb @ line 10 in Object#alpha:

     5: 
     6: 
     7: 
     8: def alpha
     9:   x = "hello"
 => 10:   beta
    11:   puts x
    12: end
    13: 
    14: def beta
    15:   binding.pry
[3] pry(main)> x = "goodbye"
=> "goodbye"
[4] pry(main)> ^D

OUTPUT: goodbye

Output from above is goodbye as we changed the x local inside the alpha (caller) stack frame.

Limitations

  • First release, so may have teething problems.
  • Limited to MRI 1.9.2+ at this stage.

Contact

Problems or questions contact me at github

License

(The MIT License)

Copyright (c) 2011 John Mair (banisterfiend)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.