Python- bytes, str, and unicode

The following is taken from: “Effective Python: 59 Specific Ways to Write Better Python” by Brett Slatkin. I highly recommend this book.

In Python 3, there are two types that represent sequences of characters: bytes and str. Instances of bytes contain raw 8-bit values. Instances of str contain Unicode characters.

In Python 2, there are two types that represent sequences of characters: str and unicode. In contrast to Python 3, instances of str contain raw 8-bit values. Instances of unicode contain Unicode characters.

… continuing…

You’ll often need two helper functions to convert between these two cases and to ensure that the type of input values matches your code’s expectations.

In Python 3, you’ll need one method that takes a str or bytes and always returns a str:

# Example 1 for python3
def to_bytes(bytes_or_str):
	if isinstance(bytes_or_str, str):
		value = bytes_or_str.encode('utf-8')
	else:
		value = bytes_or_str
	return value  # Instance of bytes

You’ll need another method that takes a str or bytes and always returns a bytes:

  # Example 2 for python3
def to_bytes(bytes_or_str):
	if isinstance(bytes_or_str, str):
		value = bytes_or_str.encode('utf-8')
	else:
		value = bytes_or_str
	return value  # Instance of bytes

In Python 2, you’ll need one method that takes a str or unicode and always returns a unicode:

  # Example 3 for python2
  def to_unicode(unicode_or_str):
	if isinstance(unicode_or_str, str):
		value = unicode_or_str.decode('utf-8')
	else:
		value = unicode_or_str
	return value  # Instance of unicode

You’ll need another method that takes str or unicode and always returns a str:

  # example 4 for python2
def to_str(unicode_or_str):
	if isinstance(unicode_or_str, unicode):
		value = unicode_or_str.encode('utf-8')
	else:
		value = unicode_or_str
	return value  # Instance of str