Module: PrettyBacktrace

Defined in:
lib/pretty_backtrace.rb,
lib/pretty_backtrace/version.rb

Constant Summary collapse

CONFIG = 
{
  truncate_length: 20,
  disabled_exception_classes: {},
  multi_line: false,
  multi_line_truncate_length: 60,
  multi_line_indent: 10,
}
EXCEPTION_MODIFIER_TRACE = 
TracePoint.new(:raise){|tp|
  begin
    e = tp.raised_exception

    CONFIG[:disabled_exception_classes].each{|klass, _|
      next if e.kind_of?(klass)
    }

    RubyVM::DebugInspector.open{|dc|
      locs = dc.backtrace_locations
      pretty_backtrace = locs.map.with_index{|loc, i|
        next if i < 2

        iseq = dc.frame_iseq(i)

        if iseq
          b = dc.frame_binding(i)
          lvs = iseq_local_variables(iseq)
          lvs_val = lvs.inject({}){|r, lv|
            v = b.local_variable_get(lv).inspect
            r[lv] = v; r
          }
        else
          lvs_val = {}
        end

        modify_trace_line loc, lvs_val
      }.compact
      e.set_backtrace pretty_backtrace
    }
  rescue => e
    puts e
    puts e.backtrace
    fail "PrettyBacktrace BUG"
  end
}
VERSION = 
"0.0.2"

Class Method Summary collapse

Class Method Details

.disable ⇒ Object 



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# File 'lib/pretty_backtrace.rb', line 60

def self.disable
  if block_given?
    EXCEPTION_MODIFIER_TRACE.disable{
      yield
    }
  else
    EXCEPTION_MODIFIER_TRACE.disable
  end
end

.enable ⇒ Object 



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# File 'lib/pretty_backtrace.rb', line 50

def self.enable
  if block_given?
    EXCEPTION_MODIFIER_TRACE.enable{
      yield
    }
  else
    EXCEPTION_MODIFIER_TRACE.enable
  end
end

.iseq_local_variables(iseq) ⇒ Object 



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# File 'lib/pretty_backtrace.rb', line 70

def self.iseq_local_variables iseq
  _,_,_,_,arg_info,name,path,a_path,_,type,lvs, * = iseq.to_a
  lvs
end

.modify_trace_line(backtrace_location, local_variables_values) ⇒ Object

local_variables_values is a Hash object containing pairs of a local variable name and value of local variable.



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# File 'lib/pretty_backtrace.rb', line 79

def self.modify_trace_line backtrace_location, local_variables_values
  trace_line = backtrace_location.to_s

  unless local_variables_values.empty?
    if CONFIG[:multi_line]
      additional = local_variables_values.map{|lv, v|
        v = v[0..CONFIG[:multi_line_truncate_length]] + '...' if v.length > CONFIG[:multi_line_truncate_length]
        ' ' * CONFIG[:multi_line_indent] + "#{lv} = #{v.to_s}"
      }.join("\n") + "\n"
      trace_line = "#{trace_line}\n#{additional}"
    else
      additional = local_variables_values.map{|lv, v|
        v = v[0..CONFIG[:truncate_length]] + '...' if v.length > CONFIG[:truncate_length]
        "#{lv} = #{v.to_s}"
      }.join(", ")
      trace_line = "#{trace_line} (#{additional})"
    end
  end

  trace_line
end