Simple manipulation of paths

modpath.py

import os, re

def modpath(p, parent=None, base=None, suffix=None):
    par, name = os.path.split(p)
    name_no_suffix, suf = os.path.splitext(name)
    if type(suffix) is str:
        suf = suffix
    if parent is not None:
        par = parent
    if base is not None:
        name_no_suffix = base

    new_path = os.path.join(par, name_no_suffix + suf)
    if type(suffix) is tuple:
        assert len(suffix) == 2
        new_path, nsubs = re.subn(r'{}$'.format(suffix[0]), suffix[1], new_path)
        assert nsubs == 1, nsubs
    return new_path

path = '/some/folder/myfile.suffix'
print(modpath(path, base='othername'))
print(modpath(path, parent='/banana/apple', suffix='.orange'))
print(modpath(path, parent='/banana/apple', suffix=''))

path = '/some/folder/myfile.suffix.othersuffix'
print(modpath(path, suffix='.orange'))
print(modpath(path, suffix=('.suffix.othersuffix', '.orange')))