debuggerメソッド、binding.pryの違いをまとめてみた。

##はじめに
本日はデバッガに関してまとめていきます。

というのも、私はdebuggerを利用していたのですが、binding.pryというデバッガの存在を知り、

双方がどのように異なるのか？理解出来ていなかったからです・・・

##結論
先に結論から申しますと、

ほぼ同じものだということです！

debuggerの後継にあたるものがbinding.pryだそうです。

とは言っても、導入の仕方や機能も多少異なりますので以下にまとめたいと思います。

##デバッガとは？

因みにですが、デバッガとは以下のことを示します。
>デバッガとは、デバッグを支援するプログラムのこと。対話的に利用者がプログラムを動作させたり、プログラムが使っている変数等を表示させる機能がある。近年では統合開発環境に含まれていることが多い。

因みに僕は、viewやテストが通らない際に、変数に何が与えられているのか確認するために使用することが多いです！

##導入の仕方
debuggerを使用するためには

```
$ gem install byebug
```

binding.pryを実行するためには

```
$ gem install pry-byebug
```
というようにそれぞれのgemをinstallする必要があります。

##使用できる機能
dubugger

```
(byebug) help

  break      -- Sets breakpoints in the source code
  catch      -- Handles exception catchpoints
  condition  -- Sets conditions on breakpoints
  continue   -- Runs until program ends, hits a breakpoint or reaches aline
  debug      -- Spawns a subdebugger
  delete     -- Deletes breakpoints
  disable    -- Disables breakpoints or displays
  display    -- Evaluates expressions every time the debugger stops
  down       -- Moves to a lower frame in the stack trace
  edit       -- Edits source files
  enable     -- Enables breakpoints or displays
  finish     -- Runs the program until frame returns
  frame      -- Moves to a frame in the call stack
  help       -- Helps you using byebug
  history    -- Shows byebug's history of commands
  info       -- Shows several informations about the program being debugged
  interrupt  -- Interrupts the program
  irb        -- Starts an IRB session
  kill       -- Sends a signal to the current process
  list       -- Lists lines of source code
  method     -- Shows methods of an object, class or module
  next       -- Runs one or more lines of code
  pry        -- Starts a Pry session
  quit       -- Exits byebug
  restart    -- Restarts the debugged program
  save       -- Saves current byebug session to a file
  set        -- Modifies byebug settings
  show       -- Shows byebug settings
  source     -- Restores a previously saved byebug session
  step       -- Steps into blocks or methods one or more times
  thread     -- Commands to manipulate threads
  tracevar   -- Enables tracing of a global variable
  undisplay  -- Stops displaying all or some expressions when program stops
  untracevar -- Stops tracing a global variable
  up         -- Moves to a higher frame in the stack trace
  var        -- Shows variables and its values
  where      -- Displays the backtrace
```

binding.pry

```
[1] pry(#<RSpec::ExampleGroups::Products>)> help
Help
  help               Show a list of commands or information about a specific command.

Context
  cd                 Move into a new context (object or scope).
  find-method        Recursively search for a method within a class/module or the current namespace.
  ls                 Show the list of vars and methods in the current scope.
  pry-backtrace      Show the backtrace for the pry session.
  raise-up           Raise an exception out of the current pry instance.
  reset              Reset the repl to a clean state.
  watch              Watch the value of an expression and print a notification whenever it changes.
  whereami           Show code surrounding the current context.
  wtf?               Show the backtrace of the most recent exception.

Editing
  /^\s*!\s*$/        Clear the input buffer.
  amend-line         Amend a line of input in multi-line mode.
  edit               Invoke the default editor on a file.
  hist               Show and replay readline history.
  play               Playback a string variable, method, line, or file as input.
  show-input         Show the contents of the input buffer for the current multi-line expression.

Introspection
  ri                 View ri documentation.
  show-doc           Show the documentation for a method or class.
  stat               View method information and set _file_ and _dir_ locals.

Gems
  gem-cd             Change working directory to specified gem's directory.
  gem-install        Install a gem and refresh the gem cache.
  gem-list           List and search installed gems.
  gem-open           Opens the working directory of the gem in your editor.
  gem-readme         Show the readme bundled with a rubygem
  gem-search         Search for a gem with the rubygems.org json api

Commands
  import-set         Import a pry command set.
  install-command    Install a disabled command.

Aliases
  !!!                Alias for `exit-program`
  !!@                Alias for `exit-all`
  $                  Alias for `show-source`
  (?-mix:whereami[!?]+) Alias for `whereami`
  ?                  Alias for `show-doc`
  @                  Alias for `whereami`
  clipit             Alias for `gist --clip`
  file-mode          Alias for `shell-mode`
  find-routes        Alias for `find-route`
  history            Alias for `hist`
  quit               Alias for `exit`
  quit-program       Alias for `exit-program`
  reload-method      Alias for `reload-code`
  show-method        Alias for `show-source`

Byebug
  backtrace          Display the current stack.
  break              Set or edit a breakpoint.
  continue           Continue program execution and end the pry session.
  down               Move current frame down.
  finish             Execute until current stack frame returns.
  frame              Move to specified frame #.
  next               Execute the next line within the current stack frame.
  step               Step execution into the next line or method.
  up                 Move current frame up.

Input and output
  .<shell command>   All text following a '.' is forwarded to the shell.
  cat                Show code from a file, pry's input buffer, or the last exception.
  change-inspector   Change the current inspector proc.
  change-prompt      Change the current prompt.
  fix-indent         Correct the indentation for contents of the input buffer
  list-inspectors    List the inspector procs available for use.
  list-prompts       List the prompts available for use.
  save-file          Export to a file using content from the repl.
  shell-mode         Toggle shell mode. bring in pwd prompt and file completion.

Misc
  gist               Upload code, docs, history to https://gist.github.com/.
  pry-version        Show pry version.
  reload-code        Reload the source file that contains the specifiedcode object.
  toggle-color       Toggle syntax highlighting.

Navigating pry
  !pry               Start a pry session on current self.
  disable-pry        Stops all future calls to pry and exits the current session.
  exit               Pop the previous binding.
  exit-program       End the current program.
  jump-to            Jump to a binding further up the stack.
  nesting            Show nesting information.
  switch-to          Start a new subsession on a binding in the currentstack.

Rails
  find-route         See which urls match a given controller.
  recognize-path     See which route matches a url.
  show-middleware    Show all middleware (that rails knows about).
  show-model         Show the given model.
  show-models        Show all models.
  show-routes        Show all routes in match order.

Prompts
  simple-prompt      Toggle the simple prompt.

Pry-byebug (v3.6.0)
  exit-all           End the current pry session.

Pry-doc (v0.13.4)
  show-source        Show the source for a method or class.
```
ふむふむ。


実際に使用できる機能はbinding.pryの方が多いようですし、コマンドも微妙に異なりますね。

たとえばbinding.pryを実行した際ではrestartコマンドが使えなかったりします。

##最後に

どちらかを使わないといけないなど決まりはありませんが、

調べてみたところbinding.pryの方が新しいこともあり、ネット上に情報が多いですね。

どちらを使用するか迷っている人は、binding.pryの方がオススメかもしれません。

【参考記事】
https://qiita.com/jnchito/items/5aaf323ab4f24b526a61