"""
min2_max2.py -- V.1.1, Sep 25 2006, by maffi leonardo.
To mimic min and max functions of Python 2.5.
Note: it supports only the first argument and the key, they don't accept many arguments.

Some tests:

>>> min2([1,2,-1])
-1
>>> min2([1])
1
>>> min2([1,2,0.1])
0.10000000000000001
>>> min2([])
Traceback (most recent call last):
 ...
ValueError: min2() arg is an empty sequence.
>>> min2([], key=lambda x:x)
Traceback (most recent call last):
 ...
ValueError: min2() arg is an empty sequence.
>>> min2([(1, "b"), (2,"a")], key=lambda (x,y):y)
(2, 'a')
>>> min2([(1, "b"), (2,"a")], key=lambda (x,y):x)
(1, 'b')

>>> def it():
...     for el in [1,2,3]: yield el
...
>>> list(it())
[1, 2, 3]
>>> min2(it())
1


>>> max2([1,2,-1])
2
>>> max2([2])
2
>>> max2([1,2.1,0.1])
2.1000000000000001
>>> max2([])
Traceback (most recent call last):
 ...
ValueError: max2() arg is an empty sequence.
>>> max2([], key=lambda x:x)
Traceback (most recent call last):
 ...
ValueError: max2() arg is an empty sequence.
>>> max2([(1, "b"), (2,"a")], key=lambda (x,y):y)
(1, 'b')
>>> max2([(1, "b"), (2,"a")], key=lambda (x,y):x)
(2, 'a')
"""

def min2(elements, key=None):
    """min2(elements, key=None): given an iterable and a key function like the key of
    sort, it returns the minimum element. This function mimics the min of Python 2.5"""
    if key is None:
        try:
            min_el = min(elements)
            return min_el
        except ValueError:
            raise ValueError, "min2() arg is an empty sequence."

    elements = iter(elements)
    try:
        min_el = elements.next()
    except StopIteration:
        raise ValueError, "min2() arg is an empty sequence."

    min_val = key(min_el)
    for el in elements:
        curr_val = key(el)
        if curr_val < min_val:
            min_el = el
            min_val = curr_val
    return min_el


def max2(elements, key=None):
    """max2(elements, key=None): given an iterable and a key function like the key of
    sort, it returns the maximum element. This function mimics the max of Python 2.5."""
    if key is None:
        try:
            max_el = max(elements)
            return max_el
        except ValueError:
            raise ValueError, "max2() arg is an empty sequence."

    elements = iter(elements)
    try:
        max_el = elements.next()
    except StopIteration:
        raise ValueError, "max2() arg is an empty sequence."

    max_val = key(max_el)
    for el in elements:
        curr_val = key(el)
        if curr_val > max_val:
            max_el = el
            max_val = curr_val
    return max_el


def _test():
    import doctest
    doctest.testmod()

if __name__ == "__main__":
    _test()
    print "min2, max2 tests finished."