An execution control add-on for Pry.

• Install: gem 'pry-moves'
• For non-rails (without auto-require), add to your script: require 'pry-moves'

Documentation for latest version. For v0.1.12 see documentation here

• n - next line in current frame, including block lines (moving to next line goes as naturally expected)
  • nn - next line in current frame, skipping block lines
• s - step into function execution
  • s method_name - step into method method_name (For example from User.new.method_name). Partial name match supported.
  • s + - step into function, including hidden frames
• f - finish execution of current frame (block or method) and stop at next line on higher level
• c - continue
• b - go to next breakpoint (methods marked with pry_breakpoint = :some_scope variable)
• add-bp var_name [line_number] - add to script in this place conditional breakpoint: debug if var_name == <it's value>
• ir - iterate, go to next iteration of current block
• g 10 - goto line 10
• bt - show backtrace, excluding hidden frames
  • bt + bt hidden - show backtrace including hidden frames
  • bt a bt all - full backtrace with system and hidden frames
  • bt 10 - go to backtrace line 10
  • bt diff - diff of backtraces (bt save for persistent save of 1st backtrace)
  • bt > foo - write backtrace to file log/backtrace_foo.log
  • bt ::ClassName - list objects in backtrace which class name contains "ClassName"
• up/down/top/bottom (bm) - move over call stack
  • up + - move up, including vapid frames (block callers, hidden frames)
  • up pattern - move up till first frame which method name or file position in format folder/script.rb:12 matches regexp pattern
• % - print current frame of call stack (alias to whereami)
• $ - fully print current function without line numbers
• debug some_method(some_param) - call some_method(some_param) and interactively step into it. This way you can virtually "step back" by executing previous pieces of code from current method
• .method or 123 or :hash_key - Continue traversing of last object in history. E.g. orders will list array, then 3 will enter orders[3], then .price will enter orders[3].price
• watch variable - display variable's value on each step
• diff expression - display difference between saved expression (on first run) and expression 2
• profile [timeout] - profile time-consuming code and infinite loops/recursion
• off - Turn off debugging (don't stop on breakpoints)
• @ - restart and reload scripts (in app/ & spec/ by default), reload rake tasks. Configurable.
• # - exit with code 3, can be wrapped in bash script to fully reload ruby scripts
• ! - exit

Variable & methods names takes precedence over commands. So if you have variable named step, to execute command step type cmd step or command's alias, e.g. s

Custom commands:

PryMoves.custom_command "say" do |args, output|
  output.puts "Pry says: #{args}"
end

To use, invoke pry normally:

def some_method
  binding.pry          # Execution will stop here.
  puts 'Hello, World!' # Run 'step' or 'next' in the console to move here.
end

Demo class source here

You can explicitly hide frames from call stack by defining variables like this:

def insignificant_method
  hide_from_stack = true
  something_insignificant
  yield
end

• hide_from_stack - hide this function from stack
• pry_moves_stack_tip - stop on first frame above this function
• pry_moves_stack_end - limits stack from bottom, not possible to step below this frame

Here is default configuration, you can reassign it:

PryMoves.reload_ruby_scripts = {
  monitor: %w(app spec),
  except: %w(app/assets app/views)
}
PryMoves.reload_rake_tasks = true
PryMoves::Backtrace::filter =
  /(\/gems\/|\/rubygems\/|\/bin\/|\/lib\/ruby\/|\/pry-moves\/)/

Turn off features with environment variables:

PRY_MOVES=off
PRY_MOVES_DEBUG_MISSING=off
PRY_MOVES_RELOADER=off

Debug:

TRACE_MOVES=on

To allow traveling to parent thread, use:

pre_callers = binding.callers
Thread.new do
  Thread.current[:pre_callers] = pre_callers
  #...
end

pry-moves can't stop other threads on binding.pry, so they will continue to run. This makes pry-moves not always suitable for debugging of multi-thread projects.

Though you can pause other threads with helper which will suspend execution on current line, until ongoing debug session will be finished with continue:

PryMoves.synchronize_threads

For example, you can put it into function which periodically reports status of thread (if you have such)

Other helpers:

• PryMoves.open? - if pry input dialog active. Can be used to suppress output from ongoing parallel threads

Rudimentary support for pry-remote (>= 0.1.1) is also included. Ensure pry-remote is loaded or required before pry-moves. For example, in a Gemfile:

gem 'pry'
gem 'pry-remote'
gem 'pry-moves'

Please note that debugging functionality is implemented through set_trace_func, which imposes heavy performance penalty while tracing (while running code within next/step/finish commands).

bin/rspec
bin/rspec -f d # Output result of each spec example

DEBUG=true bin/rspec -e 'backtrace should backtrace'

• iterate - steps in into child sub-block - should skip

• Gopal Patel (@nixme)
• John Mair (@banister)
• Conrad Irwin (@ConradIrwin)
• Benjamin R. Haskell (@benizi)
• Jason R. Clark (@jasonrclark)
• Ivo Anjo (@ivoanjo)

Patches and bug reports are welcome. Just send a pull request or file an issue.

• Gopal Patel's pry-nav
• John Mair's pry-stack_explorer
• Ruby stdlib's debug.rb
• @Mon-Ouie's pry_debug