README.md

Status: Unmaintained

I am no longer actively maintaining this project.

filelike: a python module for creating and handling file-like objects.

This module takes care of the groundwork for implementing and manipulating objects that provide a rich file-like interface, including reading, writing, seeking and iteration. It also provides a number of useful classes built on top of this functionality.

The main class is FileLikeBase, which implements the entire file-like interface on top of primitive _read(), _write(), _seek(), _tell() and _truncate() methods. Subclasses may implement any or all of these methods to obtain the related higher-level file behaviors.

It also provides some nifty file-handling functions:

:open:    mirrors the standard open() function but is much cleverer;
          URLs are automatically fetched, .bz2 files are transparently
          decompressed, and so-on.

:join:    concatenate multiple file-like objects together so that they
          act like a single file.

:slice:   access a section of a file-like object as if it were an
          independent file.

The "wrappers" subpackage contains a collection of useful classes built on top of this framework. These include:

:Translate:  pass file contents through an arbitrary translation
             function (e.g. compression, encryption, ...)
              
:Decrypt:    on-the-fly reading and writing to an encrypted file
             (using PEP272 cipher API)

:UnBZip2:    on-the-fly decompression of bzip'd files
             (like the standard library's bz2 module, but accepts
             any file-like object)

As an example of the type of thing this module is designed to achieve, here's how the Decrypt wrapper can be used to transparently access an encrypted file::

# Create the decryption key
from Crypto.Cipher import DES
cipher = DES.new('abcdefgh',DES.MODE_ECB)
# Open the encrypted file
from filelike.wrappers import Decrypt
f = Decrypt(file("some_encrypted_file.bin","r"),cipher)

The object in 'f' now behaves as a file-like object, transparently decrypting the file on-the-fly as it is read.

The "pipeline" subpackage contains facilities for composing these wrappers in the form of a unix pipeline. In the following example, 'f' will read the first five lines of an encrypted file::

from filelike.pipeline import Decrypt, Head
f = file("some_encrypted_file.bin") > Decrypt(cipher) | Head(lines=5)

Finally, two utility functions are provided for when code expects to deal with file-like objects:

:is_filelike(obj):   checks that an object is file-like
:to_filelike(obj):   wraps a variety of objects in a file-like interface