autorepr 0.2.0

Installation

$ pip install autorepr

Usage

autorepr consists of three functions. autorepr builds a Python-esque __repr__ string by passing either a str.format-style string, or a list of attributes which should be included in a name=value list. The autostr and autounicode functions are similar, and will do their best to avoid Unicode encoding / decoding errors.

>>> from autorepr import autorepr, autostr, autounicode
>>> class Person(object):
...     name = u"Alex ☃"
...     height = 123.456
...
...     __repr__ = autorepr(["name", "height:0.1f"])
...     __str__ = autostr("{self.name} ({self.height:0.0f} cm)")
...     __unicode__ = autounicode(__str__)
...
>>> p = Person()
>>> repr(p)
"<__main__.Person name=u'Alex \\u2603' height=123.5 at 0x...>"
>>> unicode(p)
u'Alex \u2603 (123 cm)'
>>> str(p)
'Alex \xe2\x98\x83 (123 cm)'

Notice that autostr and autounicode are intelligent about converting their input to/from unicode (decoding/encoding as UTF-8) as necessary:

>>> p.name = u"unicode: ☃"
>>> unicode(p)
u'unicode: \u2603 (123 cm)'
>>> str(p)
'unicode: \xe2\x98\x83 (123 cm)'
>>> p.name = 'utf-8 bytes: \xe2\x98\x83'
>>> unicode(p)
u'utf-8 bytes: \u2603 (123 cm)'
>>> str(p)
'utf-8 bytes: \xe2\x98\x83 (123 cm)'

Note: autostr and autorepr won’t crash on invalid UTF-8 (for example, if autounicode is asked to turn binary data into unicode), but the result is undefined and may not be desirable.

Additional properties can be passed in as kwargs, which will be called with the instance as a parameter:

>>> name_with_len = autostr("{self.name} length={len}",
...                         len=lambda self: len(self.name))
...
>>> p.name = 'Alex'
>>> name_with_len(p)
'Alex length=4'

This works with autorepr’s list mode too:

>>> repr_with_len = autorepr(["name", "len"],
...                          len=lambda self: len(self.name))
...
>>> repr_with_len(p)
"<__main__.Person name='Alex' len=4 at 0x...>"

If a regular format string is passed to autorepr, it will use that instead of the generated string:

>>> repr_with_str = autorepr("{self.name!r}")
>>> repr_with_str(p)
"<__main__.Person 'Alex' at 0x...>"

And of course, if you don’t want your __repr__ to be wrapped in <ClassName ...>, you can use autostr:

>>> repr_with_autostr = autostr("Person({self.name!r})")
>>> repr_with_autostr(p)
"Person('Alex')"

Format specifications can also be passed to autorepr if the default of !r is undesierable (for example, turncating floats):

>>> with_fmt_spec = autorepr(["duration:0.1f", "addr:x", "type!s"],
...                          duration=lambda x: 123.456,
...                          addr=lambda x: 0xabc123,
...                          type=lambda x: "foo")
>>> with_fmt_spec(None)
'<__builtin__.NoneType duration=123.5 addr=abc123 type=foo at 0x...>'