File: speaklater.py

package info (click to toggle)
speaklater 1.3-2
  • links: PTS, VCS
  • area: main
  • in suites: jessie, jessie-kfreebsd
  • size: 88 kB
  • ctags: 47
  • sloc: python: 163; makefile: 13
file content (200 lines) | stat: -rw-r--r-- 5,216 bytes parent folder | download
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
191
192
193
194
195
196
197
198
199
200
# -*- coding: utf-8 -*-
r"""
    speaklater
    ~~~~~~~~~~

    A module that provides lazy strings for translations.  Basically you
    get an object that appears to be a string but changes the value every
    time the value is evaluated based on a callable you provide.

    For example you can have a global `lazy_gettext` function that returns
    a lazy string with the value of the current set language.

    Example:

    >>> from speaklater import make_lazy_string
    >>> sval = u'Hello World'
    >>> string = make_lazy_string(lambda: sval)

    This lazy string will evaluate to the value of the `sval` variable.

    >>> string
    lu'Hello World'
    >>> unicode(string)
    u'Hello World'
    >>> string.upper()
    u'HELLO WORLD'

    If you change the value, the lazy string will change as well:

    >>> sval = u'Hallo Welt'
    >>> string.upper()
    u'HALLO WELT'

    This is especially handy when combined with a thread local and gettext
    translations or dicts of translatable strings:

    >>> from speaklater import make_lazy_gettext
    >>> from threading import local
    >>> l = local()
    >>> l.translations = {u'Yes': 'Ja'}
    >>> lazy_gettext = make_lazy_gettext(lambda: l.translations.get)
    >>> yes = lazy_gettext(u'Yes')
    >>> print yes
    Ja
    >>> l.translations[u'Yes'] = u'Si'
    >>> print yes
    Si

    Lazy strings are no real strings so if you pass this sort of string to
    a function that performs an instance check, it will fail.  In that case
    you have to explicitly convert it with `unicode` and/or `string` depending
    on what string type the lazy string encapsulates.

    To check if a string is lazy, you can use the `is_lazy_string` function:

    >>> from speaklater import is_lazy_string
    >>> is_lazy_string(u'yes')
    False
    >>> is_lazy_string(yes)
    True

    New in version 1.2: It's now also possible to pass keyword arguments to
    the callback used with `make_lazy_string`.

    :copyright: (c) 2010 by Armin Ronacher.
    :license: BSD, see LICENSE for more details.
"""


def is_lazy_string(obj):
    """Checks if the given object is a lazy string."""
    return isinstance(obj, _LazyString)


def make_lazy_string(__func, *args, **kwargs):
    """Creates a lazy string by invoking func with args."""
    return _LazyString(__func, args, kwargs)


def make_lazy_gettext(lookup_func):
    """Creates a lazy gettext function dispatches to a gettext
    function as returned by `lookup_func`.

    Example:

    >>> translations = {u'Yes': u'Ja'}
    >>> lazy_gettext = make_lazy_gettext(lambda: translations.get)
    >>> x = lazy_gettext(u'Yes')
    >>> x
    lu'Ja'
    >>> translations[u'Yes'] = u'Si'
    >>> x
    lu'Si'
    """
    def lazy_gettext(string):
        if is_lazy_string(string):
            return string
        return make_lazy_string(lookup_func(), string)
    return lazy_gettext


class _LazyString(object):
    """Class for strings created by a function call.

    The proxy implementation attempts to be as complete as possible, so that
    the lazy objects should mostly work as expected, for example for sorting.
    """
    __slots__ = ('_func', '_args', '_kwargs')

    def __init__(self, func, args, kwargs):
        self._func = func
        self._args = args
        self._kwargs = kwargs

    value = property(lambda x: x._func(*x._args, **x._kwargs))

    def __contains__(self, key):
        return key in self.value

    def __nonzero__(self):
        return bool(self.value)

    def __dir__(self):
        return dir(unicode)

    def __iter__(self):
        return iter(self.value)

    def __len__(self):
        return len(self.value)

    def __str__(self):
        return str(self.value)

    def __unicode__(self):
        return unicode(self.value)

    def __add__(self, other):
        return self.value + other

    def __radd__(self, other):
        return other + self.value

    def __mod__(self, other):
        return self.value % other

    def __rmod__(self, other):
        return other % self.value

    def __mul__(self, other):
        return self.value * other

    def __rmul__(self, other):
        return other * self.value

    def __lt__(self, other):
        return self.value < other

    def __le__(self, other):
        return self.value <= other

    def __eq__(self, other):
        return self.value == other

    def __ne__(self, other):
        return self.value != other

    def __gt__(self, other):
        return self.value > other

    def __ge__(self, other):
        return self.value >= other

    def __getattr__(self, name):
        if name == '__members__':
            return self.__dir__()
        return getattr(self.value, name)

    def __getstate__(self):
        return self._func, self._args, self._kwargs

    def __setstate__(self, tup):
        self._func, self._args, self._kwargs = tup

    def __getitem__(self, key):
        return self.value[key]

    def __copy__(self):
        return self

    def __repr__(self):
        try:
            return 'l' + repr(self.value)
        except Exception:
            return '<%s broken>' % self.__class__.__name__


if __name__ == '__main__':
    import doctest
    doctest.testmod()