Consider support for file like objects instead of filenames

[jayfk]

The API is currently designed in a way that it tightly coupled with the file system. The parse function for example expects the Pipfile to be a filename: https://github.com/pypa/pipfile/blob/master/pipfile/api.py#L70

It'd great if we could find a way to decouple the API from the filesystem, at least in parts. This won't work for functions like walk_up, but when I look at parse it'd relatively easy to just pass in a file like object:

def parse(self, file_handle):
    # Open the Pipfile.
    content = f.read()
    ...

Same goes for the find function. Instead of calling os.getcwd explicitly in find, call it in walk_up:

 @staticmethod
def find(max_depth=3):
     """Returns the path of a Pipfile in parent directories."""
     i = 0
     for c, d, f in walk_up():
     ...

def walk_up(bottom):
    """mimic os.walk, but walk 'up' instead of down the directory tree.
    From: https://gist.github.com/zdavkeos/1098474
    """

    bottom = os.path.realpath(os.getcwd())
    ...

This would help external tools a lot to work with the API. There are probably still a lot of design decisions to make here, but if there's any interest in supporting external tools I'd be happy to submit a PR that addresses some of the points I mentioned earlier.

[kennethreitz]

the codebaes is currently being re-written