From: Jan Roslind <jan@...>
Date: 2010-02-12T18:35:01+09:00
Subject: Re: Global rescue - DRY (don't repeat yourself)

Sorry - my fault - I should have included a running demo:


class VariableStack

  @@variables = []

  def self.save_variables (xbinding, xself)
    @@variables << [ caller[0], xbinding, xself ]
  end # self.save_variables

  def self.get_instance_variables (xself)
    xself.instance_variables.collect do |name|
      value = xself.instance_variable_get(name)
      "#{name}=#{value}"
    end
  end # self.get_instance_variables

  def self.dump_variables
    puts "Variable dump:"
    lng = @@variables.size
    0.upto(lng-1) do |i|
      xcaller, xbinding, xself = @@variables[i]
      xlocal_variables    = eval("local_variables", xbinding).collect { 
|a| "#{a}=#{eval(a, xbinding)}" }.join(', ')
      xinstance_variables = 
VariableStack.get_instance_variables(xself).join(', ')
      puts "variable_stack/#{i}:"
      puts "  caller             = #{xcaller}"
      puts "  local variables    = #{xlocal_variables}"
      puts "  instance variables = #{xinstance_variables}"
    end # each variables
    @@variables = []
  end # self.dump_variables

end # VariableStack


class SomeClass1

  def self.test1
    begin
      @some_instance_var1 = 1
      some_local_var2 = 0
      some_local_var3 = 3
      division_by_with_zero = @some_instance_var1 / 0
    rescue => e ; VariableStack.save_variables(binding, self) ; raise # 
generel rescue clause - used 10.000 times - not wery DRY
    end
  end # self.test1

end # SomeClass1


class SomeClass2

  def self.test2
    begin
      @some_instance_variable4 = 4
      some_local_var5 = 5
      SomeClass1.test1
    rescue => e ; VariableStack.save_variables(binding, self) ; raise # 
generel rescue clause - used 10.000 times - not wery DRY
    end
  end # self.test2

end # SomeClass2


# rails session, batch job or demon proces
begin
  @some_instance_variable6 = 6
  some_local_var7 = 7
  SomeClass2.test2
rescue => e
  puts "error     = #{e.message.to_s}"
  puts "backtrace = #{e.backtrace}"
  VariableStack.dump_variables
  # to-do: bug management system: save error report in database or send 
error report as mail
end

Output:

error     = divided by 0
backtrace = test.rb:41:in `/'test.rb:41:in `test1'test.rb:55:in 
`test2'test.rb:67
Variable dump:
variable_stack/0:
  caller             = test.rb:42:in `test1'
  local variables    = some_local_var2=0, some_local_var3=3, 
division_by_with_zero=, e=divided by 0
  instance variables = @some_instance_var1=1
variable_stack/1:
  caller             = test.rb:56:in `test2'
  local variables    = some_local_var5=5, e=divided by 0
  instance variables = @some_instance_variable4=4


My problem is that I don't want to repeat

rescue => e ; VariableStack.save_variables(binding, self) ; raise

for every method in my application. It would be much better with

load 'global_rescue_clause.rb', but that does not work.


Is there a way to include "row" ruby source code in ruby method, or an 
more OO way to get a variable stack with local and instance variables?


Regards
Jan
-- 
Posted via http://www.ruby-forum.com/.