Many backtraces include too much information that's not relevant for the context. This makes it hard to find the signal in the backtrace and adds debugging time. With a BacktraceCleaner, you can setup filters and silencers for your particular context, so only the relevant lines are included.

If you need to reconfigure an existing BacktraceCleaner, like the one in Rails, to show as much as possible, you can always call #remove_silencers!

Example:

bc = BacktraceCleaner.new
bc.add_filter   { |line| line.gsub(Rails.root, '') }
bc.add_silencer { |line| line =~ /mongrel|rubygems/ }
bc.clean(exception.backtrace) # will strip the Rails.root prefix and skip any lines from mongrel or rubygems

Inspired by the Quiet Backtrace gem by Thoughtbot.

Methods
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Class Public methods
new()
# File activesupport/lib/active_support/backtrace_cleaner.rb, line 18
def initialize
  @filters, @silencers = [], []
end
Instance Public methods
add_filter(&block)

Adds a filter from the block provided. Each line in the backtrace will be mapped against this filter.

Example:

# Will turn "/my/rails/root/app/models/person.rb" into "/app/models/person.rb"
backtrace_cleaner.add_filter { |line| line.gsub(Rails.root, '') }
# File activesupport/lib/active_support/backtrace_cleaner.rb, line 33
def add_filter(&block)
  @filters << block
end
add_silencer(&block)

Adds a silencer from the block provided. If the silencer returns true for a given line, it'll be excluded from the clean backtrace.

Example:

# Will reject all lines that include the word "mongrel", like "/gems/mongrel/server.rb" or "/app/my_mongrel_server/rb"
backtrace_cleaner.add_silencer { |line| line =~ /mongrel/ }
# File activesupport/lib/active_support/backtrace_cleaner.rb, line 44
def add_silencer(&block)
  @silencers << block
end
clean(backtrace)

Returns the backtrace after all filters and silencers has been run against it. Filters run first, then silencers.

# File activesupport/lib/active_support/backtrace_cleaner.rb, line 23
def clean(backtrace)
  silence(filter(backtrace))
end
remove_silencers!()

Will remove all silencers, but leave in the filters. This is useful if your context of debugging suddenly expands as you suspect a bug in the libraries you use.

# File activesupport/lib/active_support/backtrace_cleaner.rb, line 50
def remove_silencers!
  @silencers = []
end