switch get and get\!, have get take an optional block that is called …

…if the field is not set and the block's value returned

lib/protocol_buffers/runtime/message.rb

@@ -426,47 +426,39 @@ def value_for_tag?(tag)
  @set_fields[tag] || false
  end
 
- # Gets the field, throwing ArgumentError if not set
- def get(*nested_field_names)
+ # Gets the field, returning nil if not set
+ # If a block is given, this block is called and it's
+ # return value returned if the value is not set
+ def get(*nested_field_names, &b)
  if nested_field_names.size == 1
  field_name = nested_field_names.first
  field = self.class.field_for_name(field_name)
  raise ArgumentError.new unless field
- raise ArgumentError.new unless self.value_for_tag?(field.tag)
+ unless self.value_for_tag?(field.tag)
+ return b ? b.call : nil
+ end
  return self.value_for_tag(field.tag)
  end
  last_proto = nested_field_names[0..-2].inject(self) do |sub_proto, ifield_name|
  sub_field = sub_proto.class.field_for_name(ifield_name)
  raise ArgumentError.new unless sub_field
  raise ArgumentError.new unless sub_field.is_a?(ProtocolBuffers::Field::MessageField)
- raise ArgumentError.new unless sub_proto.value_for_tag?(sub_field.tag)
+ unless sub_proto.value_for_tag?(sub_field.tag)
+ return b ? b.call : nil
+ end
  sub_proto.value_for_tag(sub_field.tag)
  end
  last_field_name = nested_field_names.last
  last_field = last_proto.class.field_for_name(last_field_name)
- raise ArgumentError.new unless last_field
- raise ArgumentError.new unless last_proto.value_for_tag?(last_field.tag)
+ unless last_proto.value_for_tag?(last_field.tag)
+ return b ? b.call : nil
+ end
  last_proto.value_for_tag(last_field.tag)
  end
 
- # Gets the field, returning nil if not set
+ # Gets the field, throwing ArgumentError if not set
  def get!(*nested_field_names)
- if nested_field_names.size == 1
- field_name = nested_field_names.first
- field = self.class.field_for_name(field_name)
- raise ArgumentError.new unless field
- return self.value_for_tag?(field.tag) ? self.value_for_tag(field.tag) : nil
- end
- last_proto = nested_field_names[0..-2].inject(self) do |sub_proto, ifield_name|
- sub_field = sub_proto.class.field_for_name(ifield_name)
- raise ArgumentError.new unless sub_field
- raise ArgumentError.new unless sub_field.is_a?(ProtocolBuffers::Field::MessageField)
- return nil unless sub_proto.value_for_tag?(sub_field.tag)
- sub_proto.value_for_tag(sub_field.tag)
- end
- last_field_name = nested_field_names.last
- last_field = last_proto.class.field_for_name(last_field_name)
- last_proto.value_for_tag?(last_field.tag) ? last_proto.value_for_tag(last_field.tag) : nil
+ get(*nested_field_names) { raise ArgumentError.new("#{nested_field_names} is not set") }
  end
 
  def inspect

spec/message_spec.rb

@@ -124,8 +124,8 @@
 
  f.get(:sub3, :subsub1, :subsub_payload).should == "sub3subsubpayload"
  f.get(:i3).should == 4
- proc { f.get(:i2) }.should raise_error(ArgumentError)
- proc { f.get(:sub2) }.should raise_error(ArgumentError)
+ f.get(:i2).should == nil
+ f.get(:sub2).should == nil
  end
 
  it "correctly handles get!" do
@@ -135,7 +135,7 @@
 
  f.get!(:sub3, :subsub1, :subsub_payload).should == "sub3subsubpayload"
  f.get!(:i3).should == 4
- f.get!(:i2).should == nil
- f.get!(:sub2).should == nil
+ proc { f.get!(:i2) }.should raise_error(ArgumentError)
+ proc { f.get!(:sub2) }.should raise_error(ArgumentError)
  end
 end