mtwtkmanPiping of shell likes cat foo | sort | uniq | wc -l is very simple, clear and fun.
Python gives us the way to implement this piping idiom by overriding special method.
All you needs are only the special method __ror__ like below.
class Pipable:
def __init__(self, cmd):
if callable(cmd):
self.cmd = cmd
else:
raise ValueError
def __ror__(self, other):
return self.cmd(other)
def __call__(self, *args):
return self.cmd(*args)
OK, use it.
import os
def read_file(f):
with open(f) as fd:
return fd.read()
p1 = Pipable(read_file)
p2 = Pipable(lambda x: x.upper())
p3 = Pipable(lambda x: '-'.join(x))
f = 'foo.txt'
with open(f, 'w') as fd:
fd.write('meow')
assert p1(f) == 'meow'
assert p1(f) | p2 == 'MEOW'
assert p1(f) | p2 | p3 == 'M-E-O-W'
os.remove(f)
Now you have the simple magic of function composition in Python!
You can override other operation symbols via corresponded special methods, so let's explore there.
