Class: JobManager::OpenOnFirstWriteFile

Inherits:
Object
  • Object
show all
Defined in:
lib/jobmanager/openonfirstwritefile.rb

Overview

This class represents a stream that wraps a file stream. Its only purpose is to defer the opening of the file to first write. Thus, if the file is never written to, it is never created!

Instance Method Summary collapse

Constructor Details

#initialize(file_name, mode_string) ⇒ OpenOnFirstWriteFile

Returns a new instance of OpenOnFirstWriteFile.



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# File 'lib/jobmanager/openonfirstwritefile.rb', line 11

def initialize(file_name, mode_string)
  @file_name = file_name
  @mode_string = mode_string
  @stream = nil
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(*args, &block) ⇒ Object

Description:

This method first opens the file (if not already opened), and then forwards the call to the file stream.



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# File 'lib/jobmanager/openonfirstwritefile.rb', line 42

def method_missing(*args, &block)
  method = args.shift
  
  if (!@stream)
    directory = File.dirname(@file_name)
    begin
      FileUtils.mkdir_p(directory)
    rescue => e
      raise "Failed to create directory #{directory}, Error (#{e.class}): #{e.message}"
    end

    begin
      @stream = File.new(@file_name, @mode_string)
    rescue => e
      raise "Failed to open file #{@file_name}, Error (#{e.class}): #{e.message}"
    end
  end
  
  @stream.send(method, *args)
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/jobmanager/openonfirstwritefile.rb', line 17

def close()
  # This method needs to be explicitly defined.  If it wasn't,
  # method_missing would create the file in order to close it,
  # defeating the purpose of this class.

  if (@stream)
    @stream.close()
  end
end

#flush ⇒ Object 



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# File 'lib/jobmanager/openonfirstwritefile.rb', line 27

def flush()
  # This method needs to be explicitly defined.  If it wasn't,
  # method_missing would create the file in order to flush it,
  # defeating the purpose of this class.

  if (@stream)
    @stream.flush()
  end
end