Class: HistoryFile::FileDelegator

Inherits:
Object
  • Object
show all
Defined in:
lib/history_file/file_delegator.rb

Overview

This class delegates all method calls to the File class. The generic methods that don't revolve around one specific file, File.join for example, are just passed on. These methods are defined in EXCLUDED_METHODS.

The methods that revolve around doing something with one specific file, however, will be called with an altered Filename. Consider this example:

> fd = HistoryFile::FileDelegator.new("some_prefix")
> fd.open("/path/to/my_file.txt", "w") do |io|
>  io.puts "hello there"
> end
> puts fd.read("/path/to/my_file.txt")
=> hello there

This will pass on your block to File.open, but with a prefixed the filename. So what's really called is:

File.open("/path/to/some_prefix-my_file.txt")

For methods that get a bunch of filenames, but only filenames, as arguments, all of the filenames are patched to include the date prefix. These methods are defined in BULK_METHODS

You shouldn't need to instanciate this class directly, HistoryFile wraps this for you.

Constant Summary collapse

EXCLUDED_METHODS = 
[
  :absolute_path,
  :basename,
  :catname,
  :chmod,
  :chown,
  :compare,
  :copy,
  :directory?,
  :dirname,
  :expand_path,
  :extname,
  :fnmatch,
  :fnmatch?,
  :identical?,
  :install,
  :join,
  :lchown,
  :link,
  :makedirs,
  :move,
  :path,
  :realdirpath,
  :realpath,
  :rename,
  :split,
  :umask,
  :utime
]
BULK_METHODS = 
[
  :delete,
  :unlink,
  :safe_unlink
]
POTENTIALLY_FILE_CREATING_METHODS = 
[
  :new,
  :open
]

Instance Method Summary collapse

Constructor Details

#initialize(opts) ⇒ FileDelegator

Returns a new instance of FileDelegator.

Parameters:

  • The prefix for all methods that revolve around filenames

  • If you want to fall back to an alphabetically smaller file on Errno::ENOENT, you can supply a :fallback_glob here. It will be used with Dir.glob to find all candidates (so this should match all prefixes)



79
80
81
82
83
 
# File 'lib/history_file/file_delegator.rb', line 79

def initialize(opts)
  @prefix = opts[:prefix] or raise ArgumentError,":prefix needed"
  @fallback_glob = opts[:fallback_glob]
  @subdir = opts[:use_subdirs]
end

Instance Method Details

#delegate(*args, &block) ⇒ Object

Either

  • passes on the call directly to File (why am I not removing this feature?) or
  • adds the date prefix to the first argument or
  • adds the date prefix to all arguments


90
91
92
93
94
95
96
97
98
99
 
# File 'lib/history_file/file_delegator.rb', line 90

def delegate(*args, &block)
  method = args.slice!(0,1).first
  if EXCLUDED_METHODS.include?(method)
    File.send(method, *args, &block)
  elsif BULK_METHODS.include?(method)
    delegate_with_patched_filenames(method, *args, &block)
  else
    delegate_with_patched_filename(method, *args, &block)
  end
end

#prefixed_filename(f) ⇒ Object 



101
102
103
104
105
106
107
108
109
 
# File 'lib/history_file/file_delegator.rb', line 101

def prefixed_filename(f)
  dir  = File.dirname(f.to_s)
  file = File.basename(f.to_s)
  if @subdir
    File.join(dir, @prefix, file)
  else
    File.join(dir, "#{@prefix}-#{file}")
  end
end