Class: ConfigToolkit::YAMLWriter

Inherits:
Writer
  • Object
show all
Defined in:
lib/configtoolkit/yamlwriter.rb

Overview

This class implements the Writer interface for YAML configuration files. It basically is a wrapper over Ruby’s YAML library.

YAML natively supports Integers, Floats, Strings, and Booleans. Instances of other classes are written by Ruby to YAML configuration files by recursively writing each of the instance’s variables and noting the associated Ruby class in the YAML file. This may not be desired behavior for a configuration file, especially if the file is going to be shared with a non-Ruby program. On the other hand, if only Ruby is using the configuration the file, this behavior may well be very desirable (since arbitrarily complex objects can be supported directly by the YAML format). Thus, the YAMLWriter offers two options:

  • Only standard YAML classes will be written. Values of classes not supported natively by YAML will be converted to Strings (with to_s).

  • Non-standard YAML classes will be written (Ruby object->YAML serialization).

See YAML.txt for more details.

Defined Under Namespace

Classes: Visitor

Instance Method Summary collapse

Methods inherited from Writer

#create_containing_object_hash

Constructor Details

#initialize(stream, only_output_standard_yaml_classes) ⇒ YAMLWriter

Description:

This constructs a YAMLWriter instance for stream, where stream either is a file name (a String) or an IO object. If only_output_standard_yaml_classes, then the writer only will output standard YAML classes; all classes not native to YAML will be converted into Strings with to_s before being written. If not only_output_standard_yaml_classes, however, then Ruby serialized classes will be written to the configuration file.

Parameters:

stream

A file name (String) or an IO object. If stream is a file name, then the YAMLWriter will open the associated file.

only_output_standard_yaml_classes

Whether or not the writer should output only standard YAML classes.



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# File 'lib/configtoolkit/yamlwriter.rb', line 52

def initialize(stream, only_output_standard_yaml_classes)
  if(stream.class == String)
    @stream = File.open(stream, "w")
  else
    @stream = stream
  end

  @only_output_standard_yaml_classes = only_output_standard_yaml_classes
end

Instance Method Details

#require_symbol_parameter_names? ⇒ Boolean

Returns:

Returns false, since the YAMLWriter requires String parameter names in the Hash passed to write.

Returns:



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# File 'lib/configtoolkit/yamlwriter.rb', line 153

def require_symbol_parameter_names?
  return false
end

#write(config_hash, containing_object_name) ⇒ Object

Description:

This method writes config_hash to the underlying stream.

Parameters:

config_hash

The configuration hash to write

containing_object_name

The configuration’s containing object name



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# File 'lib/configtoolkit/yamlwriter.rb', line 167

def write(config_hash, containing_object_name)
  if(@only_output_standard_yaml_classes)
    visitor = Visitor.new()
    visitor.visit(config_hash)
    output_hash = visitor.config_hash
  else
    output_hash = config_hash
  end

  containing_object_hash = create_containing_object_hash(output_hash, containing_object_name)
  YAML::dump(containing_object_hash, @stream)
  @stream.flush()
end