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Live help
Overview
One of the design goals of Pry was for it to be self-documenting. To that end, Pry provides commands that yield documentation on nearly every aspect of Pry from within the REPL itself.
Viewing a Pry method's documentation
Since Pry is simply Ruby code, all documentation on its methods are
available using the standard
show-doc
command.
Example:
pry(main)> ? Pry#valid_expression?
From: /Users/john/.rvm/gems/ruby-1.9.2-p180/gems/pry-0.9.2/lib/pry/pry_instance.rb @ line 458:
Number of lines: 7
signature: valid_expression?(code)
Determine if a string of code is a valid Ruby expression.
Ruby 1.9 uses Ripper, Ruby 1.8 uses RubyParser.
param [String] code The code to validate.
return [Boolean] Whether or not the code is a valid Ruby expression.
example
valid_expression?("class Hello") #=> false
valid_expression?("class Hello; end") #=> true
pry(main)>
Learning about Pry's configuration options
Live help may be particularly useful when learning about Pry's
configuration options. Most of these are documented methods in the
Pry.config
namespace.
Example:
pry(main)> ls -m Pry.config
[:__binding_impl__, :color, :color=, :commands, :commands=, :editor, :editor=, :exception_handler, :exception_handler=, :has_pry_doc, :has_pry_doc=, :history, :history=, :hooks, :hooks=, :input, :input=, :memory_size, :memory_size=, :output, :output=, :pager, :pager=, :plugins, :plugins=, :print, :print=, :prompt, :prompt=, :result_pager, :result_pager=, :results_pager, :results_pager=, :should_load_plugins, :should_load_plugins=, :should_load_rc, :should_load_rc=]
pry(main)> ? Pry.config.editor
From: /Users/john/.rvm/gems/ruby-1.9.2-p180/gems/pry-0.9.2/lib/pry/config.rb @ line 58:
Number of lines: 12
signature: editor()
The default editor to use. Defaults to $EDITOR or nano if
$EDITOR is not defined.
If editor is a String then that string is used as the shell
command to invoke the editor. If editor is callable (e.g a
Proc) then file and line are passed in as parameters and the
return value of that callable invocation is used as the exact
shell command to invoke the editor.
example String
Pry.editor = "emacsclient"
example Callable
Pry.editor = proc { |file, line| "emacsclient #{file} +#{line}" }
return [String, #call]
pry(main)>
Pry command documentation
Pry's commands are not methods and so cannot easily be
documented in the same way as methods (using show-doc
). Instead commands have their own
documentation system organized around the help
command.
Typing help
at the prompt will retrieve a list of all available
commands. If you pass a parameter to help
where that parameter is
the name of a command you will restrict the output to the help for just that command.
Note that help
only returns a short description of each command,
but this is sufficient in many cases. For more complex commands the
description (retrieved by help
) will indicate that more
documentation is available by passing the --help
switch to the
command itself.
Example: A simple command
pry(main)> help cd
Start a Pry session on VAR (use `cd ..` to go back and `cd /` to return to Pry top-level)
pry(main)>
Example: A command with further documentation available
pry(main)> help show-method
Show the source for METH. Type `show-method --help` for more info. Aliases: $, show-source
pry(main)> show-method --help
Usage: show-method [OPTIONS] [METH]
Show the source for method METH. Tries instance methods first and then methods by default.
e.g: show-method hello_method
options:
-l, --line-numbers Show line numbers.
-b, --base-one Show line numbers but start numbering at 1 (useful for `amend-line` and `play` commands).
-M, --instance-methods Operate on instance methods.
-m, --methods Operate on methods.
-f, --flood Do not use a pager to view text longer than one screen.
-c, --context Select object context to run under.
-h, --help This message.
pry(main)>