The Whatever Object
An easy way to make lambdas by partial application of python operators.
Inspired by Perl 6 one, see http://perlcabal.org/syn/S02.html#The_Whatever_Object
Usage
from whatever import _, that
# get a list of guys names
names = map(_.name, guys)
names = map(that.name, guys)
odd = map(_ * 2 + 1, range(10))
squares = map(_ ** 2, range(100))
small_squares = filter(_ < 100, squares)
best = max(tries, key=_.score)
sort(guys, key=-that.height)
factorial = lambda n: reduce(_ * _, range(2, n+1))NOTE: chained comparisons cannot be implemented since there is no boolean overloading in python.
CAVEATS
In some special cases whatever can cause confusion:
_.attr # this makes callable
obj._ # this fetches '_' attribute of obj
_[key] # this works too
d[_] # KeyError, most probably
_._ # short for attrgetter('_')
_[_] # short for lambda d, k: d[k]
if _ == 'Any value':
# You will get here, definitely
# `_ == something` produces callable, which is true
[1, 2, _ * 2, None].index('hi') # => 2, since bool(_ * 2 == 'hi') is TrueAlso, whatever sometimes fails on late binding:
(_ * 2)('2') # -> NotImplemented
