FILE returns different value when using binding.pry

Question

__FILE__ returns the path of the current Ruby script file.

One potentially significant problem is that, if using binding.pry, __FILE__ evaluates to (pry). It is potentially problematic to have __FILE__ evaluate to different values depending on whether it is evaluated in the context of binding.pry. For example,

$stdout.print "****************************************\n\n"
$stdout.print "FILE: #{__FILE__}\n\n"
$stdout.print "****************************************\n\n"

binding.pry

When the script pauses at binding.pry, I get:

__FILE__
# >> (pry)

Does anyone know any mechanism to get the path of the current file even in the context of binding.pry?

Assign it before stopping. `current_file = __FILE__; binding.pry` — Sergio Tulentsev, Dec 13 '18 at 23:53
FYI you don't need to use `pry` since Ruby 2.4: `binding.irb` is built-in and largely equivalent. — Max, Dec 14 '18 at 15:33
@anothermh yep, my comment is totally unrelated to the question. Just pointing out that `pry` is no longer necessary — Max, Dec 14 '18 at 16:56

score 2 · Accepted Answer · answered Dec 14 '18 at 00:55

Use _file_ instead of __FILE__. For example, given two files:

# foo.rb
require 'pry'
require './bar'
binding.pry
b = Bar.new

and:

# bar.rb
require 'pry'
class Bar
  def initialize
    binding.pry
  end
end

Run them with ruby foo.rb:

ruby foo.rb

From: /Users/username/foo.rb @ line 3 :

    1:     require 'pry'
    2:     require './bar'
 => 3:     binding.pry
    4:     b = Bar.new

(main):1 ⇒ _file_
=> "/Users/username/foo.rb"
(main):2 ⇒ exit

From: /Users/username/bar.rb @ line 4 Bar#initialize:

    3: def initialize
 => 4:   binding.pry
    5: end

(#<Bar:0x00007fbb6caaff08>):1 ⇒ _file_
=> "/Users/username/bar.rb"

_file_ and any other local variable names can be found in binding.local_variables.

score 1 · Answer 2 · edited Dec 14 '18 at 19:11

1

Sergio Tulentsev made a simple suggestion, assign __FILE__ to a variable before invoking binding.pry.

anothermh, mentioned _file_ which is available in binding pry.

In the end, I combined the two answers:

# When in the context of binding.pry, __FILE__ resolves to '(pry)',
# binding contains the local variable _file_ which always resolves to
# the current file, even when being evaluated in the context of binding.pry .
# _file_ is only available, in binding. This does the trick:

current_file = __FILE__.downcase == '(pry)' ? _file_ : __FILE__

edited Dec 14 '18 at 19:11

anothermh

9,815
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answered Dec 14 '18 at 15:32

Peter Jirak Eldritch

763
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2

Beware that `_file_` returns the absolute path while `__FILE__` does not, so do not expect them to be perfectly interchangeable if you're subsequently parsing the value of `current_file`. I don't see any reason not to continue using just `__FILE__`, since the only time I can see `_file_` being necessary is when manually typing into the REPL. – anothermh Dec 15 '18 at 00:02

__FILE__ returns different value when using binding.pry

2 Answers2

FILE returns different value when using binding.pry