morphys 1.0

Smart conversions between unicode and bytes types for common cases

Morphys is a simple, small library providing utilities for easy smart conversions between unicode and bytes types.

In Python 2, the treatment of unicode and bytes objects is a potential source of many surprising and annoying errors, should a non-ASCII character appear anywhere in a string.

The two types are completely equivalent if only ASCII characters are used, and many libraries treat them as such, while others are more vigilant about which type they accept. Some can even return one or the other type of string from the same function depending on the content (for example, the standard library json module).

Morphys is meant to help with cases where types of strings handled by libraries are inconsistent or undocumented. Or where simply both types of string can appear, but should be coerced to the same type before being handled.

Conversion functions

Morphys provides two functions for smart conversions to unicode or bytes. They just return their argument unchanged if it’s already the right type and can also convert any object defining the __unicode__ (or __str__ in Python 3) “magic” method.

ensure_bytes(obj, encoding=None)

Return obj as a bytes object, if necessary encoding it using encoding.

ensure_unicode(obj, encoding=None)

Return obj as an unicode object, if necessary decoding it using encoding.

See docstrings in the module for more detailed description of the functions.

Lazy conversion wrapper

In certain cases it may be more convenient to use an object that can be used both as bytes or unicode as needed. The class StrMorpher is provided for this case. Its constructor takes the same arguments as the conversion functions. The object makes calls to the appropriate conversion function when its “magic” methods that convert to bytes or unicode are invoked.

Note, that StrMorpher is not itself a subclass of any of the string types and relies on the “magic” methods being called to produce the actual string objects.

See docstrings in the module for more detailed description of the class.

Default encoding

The encoding parameter is optional in all places where it’s accepted. Where it is left as None, the default encoding is used.

The default encoding is controlled by default_encoding global variable in the morphys module. Initially it’s set to “utf-8”, but it’s allowed to set it to a different encoding name from user code.

Python 3

While Morphys is mostly meant to solve issues of string types handling in Python 2, it’s fully compatible with Python 3 and can be used with it.