# WebHelpers / webhelpers / misc.py

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190``` ```"""Helpers that are neither text, numeric, container, or date. """ import itertools import types 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 def flatten(iterable): """Recursively iterate lists and tuples. Examples: >>> list(flatten([1, [2, 3], 4])) [1, 2, 3, 4] >>> list(flatten([1, (2, 3, [4]), 5])) [1, 2, 3, 4, 5] """ for elm in iterable: if isinstance(elm, (list, tuple)): for relm in flatten(elm): yield relm else: yield elm def subclasses_only(class_, it, exclude=None): """Extract the subclasses of a class from a module, dict, or iterable. Return a list of subclasses found. The class itself will not be included. This is useful to collect the concrete subclasses of an abstract base class. ``class_`` is a class. ``it`` is a dict or iterable. If a dict is passed, examine its values, not its keys. To introspect the current module, pass ``globals()``. To introspect another module or namespace, pass ``vars(the_module_or_namespace)``. ``exclude`` is an optional list of additional classes to ignore. This is mainly used to exclude abstract subclasses. """ if isinstance(it, dict): it = it.itervalues() class_types = (type, types.ClassType) ignore = [class_] if exclude: ignore.extend(exclude) return [x for x in it if isinstance(x, class_types) and issubclass(x, class_) and x not in ignore] class DeclarativeException(Exception): """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 """ message = "" def __init__(self, message=None): Exception.__init__(self, message or self.message) class OverwriteError(Exception): """Refusing to overwrite an existing file or directory.""" def __init__(self, filename, message="not overwriting '%s'"): message %= (filename,) Exception.__init__(self, message) self.filename = filename if __name__ == "__main__": import doctest doctest.testmod() ```