What if my choice branches also include the field which makes the choice? about bindata HOT 4 CLOSED

http://github.com/dmendel/bindata/wiki/FAQ#how-do-i-model-this-complex-nested-format

There are examples of implementing tagged structures here:

• http://github.com/dmendel/bindata/blob/master/examples/tcp_ip.rb
• http://github.com/dmendel/bindata/blob/master/examples/list.rb
• http://github.com/dmendel/bindata/blob/master/examples/nbt.rb

The difficulty working out how to implement these types of nestings is understanding that tag belongs outside the structure, not inside. Think table-oriented rather than object-oriented.

Your implementation should look something like:

class CONSTANT_Methodref_info < BinData::Record
  endian  :big
  uint16  :class_index
  uint16  :name_and_type_index
end

class CONSTANT_NameAndType_info < BinData::Record
  endian  :big
  uint16  :name_index
  uint16  :descriptor_index
end

class Cp_info < BinData::Record
  endian  :big
  uint8   :tag
  choice  :payload, :selection => :tag do
    constant_methodref_info 10
    constant_name_and_type_info 12
  end
end

from bindata.

@dmendel, missed do keyword in choice line?

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@korun fixed. Thanks.

from bindata.

Yeah, I was already aware of that workaround but was hoping there might be a way which didn't require me to change from the documented structure.

I guess I can always extend and add different type of choice, if need be.

from bindata.