Class: FileWriter

Inherits:
Object
  • Object
show all
Defined in:
lib/file_writer.rb,
lib/file_writer/version.rb

Overview

Overwrite files safely

Constant Summary collapse

VERSION = 
"0.1.2"

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(fname) ⇒ FileWriter

Create new FileWriter

Parameters:

  • String —

    fname The name of he file to overwrite



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# File 'lib/file_writer.rb', line 14

def initialize(fname)
  @fname = fname
end

Instance Attribute Details

#fname ⇒ Object (readonly)

The filename of the file to overwrite



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# File 'lib/file_writer.rb', line 9

def fname
  @fname
end

Class Method Details

.write(fname, contents) ⇒ Object

Overwrite the file

Parameters:

  • String —

    fname The name of the file to overwrite

  • String —

    contents The new contents for the file.



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# File 'lib/file_writer.rb', line 52

def self.write(fname, contents)
  FileWriter.new(fname).write(contents)
end

Instance Method Details

#write(contents) ⇒ Object

Overwrite the file

Parameters:

  • String —

    contents The new contents for the file.



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# File 'lib/file_writer.rb', line 22

def write(contents)
  backup = fname + "~"

  existing = File.exists?(fname)

  if existing
    mode   = File.stat(fname).mode
    begin
      File.rename(fname, backup)
    rescue SystemCallError
      FileUtils.cp(fname,fname+"~")
    end
  else
    mode = nil
  end

  File.open(fname, "wb+", mode) do |f|
    if f.syswrite(contents) != contents.bytesize
      raise SystemCallError.new("FileWriter#write: syswrite returned unexpected length")
    end
    f.flush
    f.fsync
  end
end