misc – Miscellaneous helpers¶

webhelpers.misc¶

webhelpers.misc.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.

webhelpers.misc.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.

webhelpers.misc.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.

webhelpers.misc.count_true(seq, pred=<function <lambda> at 0x47e22a8>)¶

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.

webhelpers.misc.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

class webhelpers.misc.DeclarativeException(message=None)¶

A simpler way to define an exception with a fixed message.

Subclasses have a class attribute .message, which is used if no message is passed to the constructor. The default message is the empty string.

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