f-strings...sorta

Python 3.6 f-strings are pretty awesome. It's too bad you can't use them in 2.7 or 3.5. With fstrings you can...sorta. The fstrings module provides a function f that acts similar to f-strings. Pass a string with str.format tokens and f will return a string formatted using the available globals and locals. Like this:

>>> from fstrings import f
>>> x = 'Hello, World...'
>>> f('{x}')
'Hello, World...'

You can't evaluate arbitrary python code within the format tokens like you can in Python 3.6, but, some of that lost functionality is gained by allowing you to pass args and kwargs to f. For example, you can still use positional arguments with f:

>>> x = 'World...'
>>> f('{} {x}', 'Hello,')
'Hello, World...'

Or you could override globals and locals by passing keyword arguments:

>>> x = 'Hello'
>>> y = 'World...'
>>> f('{x}, {y}', x='Goodbye')
'Goodbye, World...'

Or do both, it's your life. In addition to f, fstrings also provides some other nifty stuff.

fdocstring Decorator

>>> from fstrings import fdocstring
>>> x = 'Hello from ya docs'
>>> @fdocstring()
... def func():
...     '''{x}'''
...
>>> func.__doc__
'Hello from ya docs'

Right now you might be thinking, "Cool, fdocstring provides the same funcality as f, but, for doc strings." You would be correct. You can even use fdocstring to format class doc strings:

>>> x = 'BOOM!'
>>> @fdocstring()
... class Obj(object):
...     '''{x}'''
...     def method(self):
...         '''{x}'''
...
>>> Obj.__doc__
'BOOM!'
>>> Obj.method.__doc__
'BOOM!'

"Boom boom" is right. Methods are auto formatted too.

printf?

After implementing f, printf was too obvious not to implement.

>>> from fstrings import printf
>>> x = 'PRINTFED'
>>> printf('{x}')
PRINTFED

printf and fdocstring accept args and kwargs for overriding globals and locals just like f.

Features and Differences

• Uses str.format instead of evaluating python code in {}
• Allows overriding globals and locals by passing in *args and **kwargs
• Supports python 2.7 to python 3.6

Tests

fstrings comes with a robust set of tests. pip install nose and run them if you like.

> nosetests -v --with-coverage --with-doctest --doctest-extension rst

Similar Projects

If you're looking for an implementation truer to Python 3.6 f-strings check out fmt.