"""Helpers that are neither text, numeric, container, or date.
"""
import itertools
def all(seq, pred=None):
"""Is ``pred(elm)`` true for all elements?
With the default predicate, this is the same as Python 2.5's ``all()``
function; i.e., it returns true if all elements are true.
>>> all(["A", "B"])
True
>>> all(["A", ""])
False
>>> all(["", ""])
False
>>> all(["A", "B", "C"], lambda x: x <= "C")
True
>>> all(["A", "B", "C"], lambda x: x < "C")
False
From recipe in itertools docs.
"""
for elm in itertools.ifilterfalse(pred, seq):
return False
return True
def any(seq, pred=None):
"""Is ``pred(elm)`` is true for any element?
With the default predicate, this is the same as Python 2.5's ``any()``
function; i.e., it returns true if any element is true.
>>> any(["A", "B"])
True
>>> any(["A", ""])
True
>>> any(["", ""])
False
>>> any(["A", "B", "C"], lambda x: x <= "C")
True
>>> any(["A", "B", "C"], lambda x: x < "C")
True
From recipe in itertools docs.
"""
for elm in itertools.ifilter(pred, seq):
return True
return False
def no(seq, pred=None):
"""Is ``pred(elm)`` false for all elements?
With the default predicate, this returns true if all elements are false.
>>> no(["A", "B"])
False
>>> no(["A", ""])
False
>>> no(["", ""])
True
>>> no(["A", "B", "C"], lambda x: x <= "C")
False
>>> no(["X", "Y", "Z"], lambda x: x <="C")
True
From recipe in itertools docs.
"""
for elm in itertools.ifilter(pred, seq):
return False
return True
def count_true(seq, pred=lambda x: x):
"""How many elements is ``pred(elm)`` true for?
With the default predicate, this counts the number of true elements.
>>> count_true([1, 2, 0, "A", ""])
3
>>> count_true([1, "A", 2], lambda x: isinstance(x, int))
2
This is equivalent to the ``itertools.quantify`` recipe, which I couldn't
get to work.
"""
ret = 0
for x in seq:
if pred(x):
ret += 1
return ret
def convert_or_none(value, type_):
"""Return the value converted to the type, or None if error.
``type_`` may be a Python type or any function taking one argument.
>>> print convert_or_none("5", int)
5
>>> print convert_or_none("A", int)
None
"""
try:
return type_(value)
except Exception:
return None
class DeclarativeException(Exception):
"""A simpler way to define an exception with a fixed message.
Example:
>>> class MyException(DeclarativeException):
... message="can't frob the bar when foo is enabled"
...
>>> try:
... raise MyException()
... except Exception, e:
... print e
...
can't frob the bar when foo is enabled
"""
message=""
def __init__(self, message=None):
Exception.__init__(self, message or self.message)
if __name__ == "__main__":
import doctest
doctest.testmod()