Class: Utils::Properties

Inherits:
Object
  • Object
show all
Defined in:
lib/utils/properties.rb

Overview

Utility class that provides the ability to load java style properties files. The files can also contain references to any property using the $key format. References are evaluated only when a property’s value is requested.

Example:

Load property files. p = Utils::Properties.load_from_file(“example.properties”, true) Utils::Properties.load_from_file(“override.properties”, true, p) # Override…

Adds the property that was referenced in example.properties. Since this is not a String, it will not be eligible for evaluation. It will still be used as a reference though. p.add_property(“time_now”, Time.now)

Configuring the root logger so that trace information can be seen. console_appender_2 = LogEasy::ConsoleAppender.new # Simple console appender. console_appender_2.formatter = LogEasy::Appender::FULL_LOGGER_NAME_FORMATTER root_logger = LogEasy::Logger.root_logger # Get the handle to the root logger. The root logger’s default level is ALL. root_logger.add_appender(console_appender_2) # Add the appenders to the root logger.

Access the property values. full_name = p.full_name author = p.author information = p.information

Print the information. puts “App: #full_name” puts “Author: #author” puts “Built: #information”

Constant Summary collapse

@@logger = 
LogEasy::Logger.get_logger(name)

Class Method Summary collapse

Instance Method Summary collapse

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(symbol, *args, &block) ⇒ Object (private)

Property values can be accessed directly using the name of the property. i.e. p.app_name (where app_name is the name of the property).



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# File 'lib/utils/properties.rb', line 123

def method_missing(symbol, *args, &block)
  # Use 'get' to get the property's value. It will raise an exception if it does not exist.
  get(symbol, *args)
end

Class Method Details

.load_from_file(file_path, evaluate_properties = true, existing_properties = Properties.new(evaluate_properties)) ⇒ Object

Creates a new Properties object by loading the specified file. Optionally an existing properties object can be passed in to put the loaded properties into. Existing properties with the same key will be overwritten. Also the evaluate properties flag can be turned off if it is not required.

Comments (lines starting with ‘#’) and empty lines are skipped.

Returns => Properties



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# File 'lib/utils/properties.rb', line 50

def Properties.load_from_file(file_path, evaluate_properties = true, existing_properties = Properties.new(evaluate_properties))
  raise "Properties file not found!" if not File.exists?(file_path)
  # Read each line, check if it is empty, a comment or starts with an =. If it does then skip it and go to the next line.
  File.open(file_path, 'r') do |file|
    line_number = 0
    file.read.each_line do |line|
      line.strip!
      line_number += 1
      # Skip empty / comment lines.
      next if (line.length == 0 or line[0] == ?#)
      # Exception for invalid first character.
      raise "Invalid property format on line #{line_number}." if line[0] == ?=

      i = line.index("=")
      if i
        # Extract the key and value.
        name = line[0..i - 1].strip
        value = line[i + 1..-1].strip
        @@logger.trace("Property '#{name}=#{value} added.")
        existing_properties.add_property(name, value)
      else
        # Not a key-value pair.
        raise "Invalid property format on line #{line_number}."
      end
    end
  end
  # Return the updated / new properties.
  existing_properties
end

Instance Method Details

#add_property(name, value) ⇒ Object

Saves a properties value. If a property with this name already exists, it is replaced with this one. Its evaluated flag is also reset. The name is converted to a Symbol and used as the key.



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# File 'lib/utils/properties.rb', line 82

def add_property(name, value)
  property = Property.new(name, value)
  key = name.to_sym
  props[key] = property
end

#evaluate_all ⇒ Object

Force evaluation of all properties right now.



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# File 'lib/utils/properties.rb', line 89

def evaluate_all
  props.each_key { |key| get(key, true) }
end

#get(key, force_evaluate = false, evaluate_property = evaluate_properties) ⇒ Object

Gets the value (as a String) of a property. The key used must be a Symbol. If ‘force_evaluate’ is set to true, the property (and all referenced properties) will be re-evaluated. If ‘evaluate_property’ is set to true all nested references will be evaluated even if the global ‘evaluate_properties’ flag is false.

Returns => String



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# File 'lib/utils/properties.rb', line 98

def get(key, force_evaluate = false, evaluate_property = evaluate_properties)
  raise "Property '#{key}' not found!" if not props.has_key?(key)
  # The property exists. Get it. Evaluate it if required.
  property = props[key]
  property.evaluate(force_evaluate) do |ref_key|
    next false if not props.has_key?(ref_key)
    next get(ref_key, force_evaluate, evaluate_property)
  end if evaluate_property
  # Return the value of the fully evaluated property.
  property.evaluated_value
end