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Commit a22b576d authored by Fred Drake's avatar Fred Drake
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UserString class from Peter Funk <pf@artcom-gmbh.de>.

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Doc/lib/libuserdict.tex
View file @ a22b576d
......@@ -63,3 +63,52 @@ provide the following attribute:
A real Python list object used to store the contents of the
\class{UserList} class.
\end{memberdesc}
\section{\module{UserString} ---
Class wrapper for string objects}
\declaremodule{standard}{UserString}
\modulesynopsis{Class wrapper for string objects.}
\moduleauthor{Peter Funk}{pf@artcom-gmbh.de}
\sectionauthor{Peter Funk}{pf@artcom-gmbh.de}
This module defines a class that acts as a wrapper around
string objects. It is a useful base class for
your own string-like classes, which can inherit from
them and override existing methods or add new ones. In this way one
can add new behaviours to strings.
The \module{UserString} module defines the \class{UserString} class:
\begin{classdesc}{UserString}{\optional{sequence}}
Return a class instance that simulates a string or an unicode string object.
The instance's content is kept in a regular string or unicode string
object, which is accessible via the
\member{data} attribute of \class{UserString} instances. The instance's
contents are initially set to a copy of \var{sequence}.
\var{sequence} can be either a regular Python string or unicode string,
an instance of \class{UserString} (or a subclass) or an arbitrary sequence
which can be converted into a string.
supporting.
\end{classdesc}
In addition to supporting the methods and operations of string or
unicode objects (see section \ref{typesseq}), \class{UserString} instances
provide the following attribute:
\begin{memberdesc}{data}
A real Python string or unicode object used to store the content of the
\class{UserString} class.
\end{memberdesc}
\begin{classdesc}{MutableString}{\optional{sequence}}
This class is derived from the \class{UserString} above and redefines
strings to be \emph{mutable}. Mutable strings can't be used as
dictionary keys, because dictionaries require \emph{immutable} objects as
keys. The main intention of this class is to serve as an educational
example for inheritance and necessity to remove (override) the
\function{__hash__} method in order to trap attempts to use a
mutable object as dictionary key, which would be otherwise very
errorprone and hard to track down.
\end{classdesc}
Lib/UserString.py 0 → 100755
View file @ a22b576d
#!/usr/bin/env python
## vim:ts=4:et:nowrap
"""A user-defined wrapper around string objects
Note: string objects have grown methods in Python 1.6
This module requires Python 1.6 or later.
"""
from types import StringType, UnicodeType
import sys
class UserString:
def __init__(self, seq):
if isinstance(seq, StringType) or isinstance(seq, UnicodeType):
self.data = seq
elif isinstance(seq, UserString):
self.data = seq.data[:]
else:
self.data = str(seq)
def __str__(self): return str(self.data)
def __repr__(self): return repr(self.data)
def __int__(self): return int(self.data)
def __long__(self): return long(self.data)
def __float__(self): return float(self.data)
def __complex__(self): return complex(self.data)
def __hash__(self): return hash(self.data)
def __cmp__(self, string):
if isinstance(string, UserString):
return cmp(self.data, string.data)
else:
return cmp(self.data, string)
def __contains__(self, char):
return char in self.data
def __len__(self): return len(self.data)
def __getitem__(self, index): return self.__class__(self.data[index])
def __getslice__(self, start, end):
start = max(start, 0); end = max(end, 0)
return self.__class__(self.data[start:end])
def __add__(self, other):
if isinstance(other, UserString):
return self.__class__(self.data + other.data)
elif isinstance(other, StringType) or isinstance(other, UnicodeType):
return self.__class__(self.data + other)
else:
return self.__class__(self.data + str(other))
def __radd__(self, other):
if isinstance(other, StringType) or isinstance(other, UnicodeType):
return self.__class__(other + self.data)
else:
return self.__class__(str(other) + self.data)
def __mul__(self, n):
return self.__class__(self.data*n)
__rmul__ = __mul__
# the following methods are defined in alphabetical order:
def capitalize(self): return self.__class__(self.data.capitalize())
def center(self, width): return self.__class__(self.data.center(width))
def count(self, sub, start=0, end=sys.maxint):
return self.data.count(sub, start, end)
def encode(self, encoding=None, errors=None): # XXX improve this?
if encoding:
if errors:
return self.__class__(self.data.encode(encoding, errors))
else:
return self.__class__(self.data.encode(encoding))
else:
return self.__class__(self.data.encode())
def endswith(self, suffix, start=0, end=sys.maxint):
return self.data.endswith(suffix, start, end)
def expandtabs(self, tabsize=8):
return self.__class__(self.data.expandtabs(tabsize))
def find(self, sub, start=0, end=sys.maxint):
return self.data.find(sub, start, end)
def index(self, sub, start=0, end=sys.maxint):
return self.data.index(sub, start, end)
def isdecimal(self): return self.data.isdecimal()
def isdigit(self): return self.data.isdigit()
def islower(self): return self.data.islower()
def isnumeric(self): return self.data.isnumeric()
def isspace(self): return self.data.isspace()
def istitle(self): return self.data.istitle()
def isupper(self): return self.data.isupper()
def join(self, seq): return self.data.join(seq)
def ljust(self, width): return self.__class__(self.data.ljust(width))
def lower(self): return self.__class__(self.data.lower())
def lstrip(self): return self.__class__(self.data.lstrip())
def replace(self, old, new, maxsplit=-1):
return self.__class__(self.data.replace(old, new, maxsplit))
def rfind(self, sub, start=0, end=sys.maxint):
return self.data.rfind(sub, start, end)
def rindex(self, sub, start=0, end=sys.maxint):
return self.data.rindex(sub, start, end)
def rjust(self, width): return self.__class__(self.data.rjust(width))
def rstrip(self): return self.__class__(self.data.rstrip())
def split(self, sep=None, maxsplit=-1):
return self.data.split(sep, maxsplit)
def splitlines(self, maxsplit=-1): return self.data.splitlines(maxsplit)
def startswith(self, prefix, start=0, end=sys.maxint):
return self.data.startswith(prefix, start, end)
def strip(self): return self.__class__(self.data.strip())
def swapcase(self): return self.__class__(self.data.swapcase())
def title(self): return self.__class__(self.data.title())
def translate(self, table, deletechars=""):
return self.__class__(self.data.translate(table, deletechars))
def upper(self): return self.__class__(self.data.upper())
class MutableString(UserString):
"""mutable string objects
Python strings are immutable objects. This has the advantage, that
strings may be used as dictionary keys. If this property isn't needed
and you insist on changing string values in place instead, you may cheat
and use MutableString.
But the purpose of this class is an educational one: to prevent
people from inventing their own mutable string class derived
from UserString and than forget thereby to remove (override) the
__hash__ method inherited from ^UserString. This would lead to
errors that would be very hard to track down.
A faster and better solution is to rewrite your program using lists."""
def __init__(self, string=""):
self.data = string
def __hash__(self):
raise TypeError, "unhashable type (it is mutable)"
def __setitem__(self, index, sub):
if index < 0 or index >= len(self.data): raise IndexError
self.data = self.data[:index] + sub + self.data[index+1:]
def __delitem__(self, index):
if index < 0 or index >= len(self.data): raise IndexError
self.data = self.data[:index] + self.data[index+1:]
def __setslice__(self, start, end, sub):
start = max(start, 0); end = max(end, 0)
if isinstance(sub, UserString):
self.data = self.data[:start]+sub.data+self.data[end:]
elif isinstance(sub, StringType) or isinstance(sub, UnicodeType):
self.data = self.data[:start]+sub+self.data[end:]
else:
self.data = self.data[:start]+str(sub)+self.data[end:]
def __delslice__(self, start, end):
start = max(start, 0); end = max(end, 0)
self.data = self.data[:start] + self.data[end:]
def immutable(self):
return UserString(self.data)
if __name__ == "__main__":
# execute the regression test to stdout, if called as a script:
import os
called_in_dir, called_as = os.path.split(sys.argv[0])
called_in_dir = os.path.abspath(called_in_dir)
called_as, py = os.path.splitext(called_as)
sys.path.append(os.path.join(called_in_dir, 'test'))
if '-q' in sys.argv:
import test_support
test_support.verbose = 0
__import__('test_' + called_as.lower())
Lib/test/test_userstring.py 0 → 100755
View file @ a22b576d
#!/usr/bin/env python
import sys, string
from test_support import verbose
# UserString is a wrapper around the native builtin string type.
# UserString instances should behave similar to builtin string objects.
# The test cases were in part derived from 'test_string.py'.
from UserString import UserString
if __name__ == "__main__":
verbose = 0
tested_methods = {}
def test(methodname, input, *args):
global tested_methods
tested_methods[methodname] = 1
if verbose:
print '%s.%s(%s) ' % (input, methodname, args),
u = UserString(input)
objects = [input, u, UserString(u)]
res = [""] * 3
for i in range(3):
object = objects[i]
try:
f = getattr(object, methodname)
res[i] = apply(f, args)
except:
res[i] = sys.exc_type
if res[0] != res[1]:
if verbose:
print 'no'
print `input`, f, `res[0]`, "<>", `res[1]`
else:
if verbose:
print 'yes'
if res[1] != res[2]:
if verbose:
print 'no'
print `input`, f, `res[1]`, "<>", `res[2]`
else:
if verbose:
print 'yes'
test('capitalize', ' hello ')
test('capitalize', 'hello ')
test('center', 'foo', 0)
test('center', 'foo', 3)
test('center', 'foo', 16)
test('ljust', 'foo', 0)
test('ljust', 'foo', 3)
test('ljust', 'foo', 16)
test('rjust', 'foo', 0)
test('rjust', 'foo', 3)
test('rjust', 'foo', 16)
test('count', 'abcabcabc', 'abc')
test('count', 'abcabcabc', 'abc', 1)
test('count', 'abcabcabc', 'abc', -1)
test('count', 'abcabcabc', 'abc', 7)
test('count', 'abcabcabc', 'abc', 0, 3)
test('count', 'abcabcabc', 'abc', 0, 333)
test('find', 'abcdefghiabc', 'abc')
test('find', 'abcdefghiabc', 'abc', 1)
test('find', 'abcdefghiabc', 'def', 4)
test('rfind', 'abcdefghiabc', 'abc')
test('index', 'abcabcabc', 'abc')
test('index', 'abcabcabc', 'abc', 1)
test('index', 'abcabcabc', 'abc', -1)
test('index', 'abcabcabc', 'abc', 7)
test('index', 'abcabcabc', 'abc', 0, 3)
test('index', 'abcabcabc', 'abc', 0, 333)
test('rindex', 'abcabcabc', 'abc')
test('rindex', 'abcabcabc', 'abc', 1)
test('rindex', 'abcabcabc', 'abc', -1)
test('rindex', 'abcabcabc', 'abc', 7)
test('rindex', 'abcabcabc', 'abc', 0, 3)
test('rindex', 'abcabcabc', 'abc', 0, 333)
test('lower', 'HeLLo')
test('lower', 'hello')
test('upper', 'HeLLo')
test('upper', 'HELLO')
test('title', ' hello ')
test('title', 'hello ')
test('title', "fOrMaT thIs aS titLe String")
test('title', "fOrMaT,thIs-aS*titLe;String")
test('title', "getInt")
test('expandtabs', 'abc\rab\tdef\ng\thi')
test('expandtabs', 'abc\rab\tdef\ng\thi', 8)
test('expandtabs', 'abc\rab\tdef\ng\thi', 4)
test('expandtabs', 'abc\r\nab\tdef\ng\thi', 4)
test('islower', 'a')
test('islower', 'A')
test('islower', '\n')
test('islower', 'abc')
test('islower', 'aBc')
test('islower', 'abc\n')
test('isupper', 'a')
test('isupper', 'A')
test('isupper', '\n')
test('isupper', 'ABC')
test('isupper', 'AbC')
test('isupper', 'ABC\n')
test('isdigit', ' 0123456789')
test('isdigit', '56789')
test('isdigit', '567.89')
test('isdigit', '0123456789abc')
test('isspace', '')
test('isspace', ' ')
test('isspace', ' \t')
test('isspace', ' \t\f\n')
test('istitle', 'a')
test('istitle', 'A')
test('istitle', '\n')
test('istitle', 'A Titlecased Line')
test('istitle', 'A\nTitlecased Line')
test('istitle', 'A Titlecased, Line')
test('istitle', 'Not a capitalized String')
test('istitle', 'Not\ta Titlecase String')
test('istitle', 'Not--a Titlecase String')
test('splitlines', "abc\ndef\n\rghi")
test('splitlines', "abc\ndef\n\r\nghi")
test('splitlines', "abc\ndef\r\nghi")
test('splitlines', "abc\ndef\r\nghi\n")
test('splitlines', "abc\ndef\r\nghi\n\r")
test('splitlines', "\nabc\ndef\r\nghi\n\r")
test('splitlines', "\nabc\ndef\r\nghi\n\r")
test('splitlines', "\nabc\ndef\r\nghi\n\r")
test('split', 'this is the split function')
test('split', 'a|b|c|d', '|')
test('split', 'a|b|c|d', '|', 2)
test('split', 'a b c d', None, 1)
test('split', 'a b c d', None, 2)
test('split', 'a b c d', None, 3)
test('split', 'a b c d', None, 4)
test('split', 'a b c d', None, 0)
test('split', 'a b c d', None, 2)
test('split', 'a b c d ')
# join now works with any sequence type
class Sequence:
def __init__(self): self.seq = 'wxyz'
def __len__(self): return len(self.seq)
def __getitem__(self, i): return self.seq[i]
test('join', '', ('a', 'b', 'c', 'd'))
test('join', '', Sequence())
test('join', '', 7)
class BadSeq(Sequence):
def __init__(self): self.seq = [7, 'hello', 123L]
test('join', '', BadSeq())
test('strip', ' hello ')
test('lstrip', ' hello ')
test('rstrip', ' hello ')
test('strip', 'hello')
test('swapcase', 'HeLLo cOmpUteRs')
transtable = string.maketrans("abc", "xyz")
test('translate', 'xyzabcdef', transtable, 'def')
transtable = string.maketrans('a', 'A')
test('translate', 'abc', transtable)
test('translate', 'xyz', transtable)
test('replace', 'one!two!three!', '!', '@', 1)
test('replace', 'one!two!three!', '!', '')
test('replace', 'one!two!three!', '!', '@', 2)
test('replace', 'one!two!three!', '!', '@', 3)
test('replace', 'one!two!three!', '!', '@', 4)
test('replace', 'one!two!three!', '!', '@', 0)
test('replace', 'one!two!three!', '!', '@')
test('replace', 'one!two!three!', 'x', '@')
test('replace', 'one!two!three!', 'x', '@', 2)
test('startswith', 'hello', 'he')
test('startswith', 'hello', 'hello')
test('startswith', 'hello', 'hello world')
test('startswith', 'hello', '')
test('startswith', 'hello', 'ello')
test('startswith', 'hello', 'ello', 1)
test('startswith', 'hello', 'o', 4)
test('startswith', 'hello', 'o', 5)
test('startswith', 'hello', '', 5)
test('startswith', 'hello', 'lo', 6)
test('startswith', 'helloworld', 'lowo', 3)
test('startswith', 'helloworld', 'lowo', 3, 7)
test('startswith', 'helloworld', 'lowo', 3, 6)
test('endswith', 'hello', 'lo')
test('endswith', 'hello', 'he')
test('endswith', 'hello', '')
test('endswith', 'hello', 'hello world')
test('endswith', 'helloworld', 'worl')
test('endswith', 'helloworld', 'worl', 3, 9)
test('endswith', 'helloworld', 'world', 3, 12)
test('endswith', 'helloworld', 'lowo', 1, 7)
test('endswith', 'helloworld', 'lowo', 2, 7)
test('endswith', 'helloworld', 'lowo', 3, 7)
test('endswith', 'helloworld', 'lowo', 4, 7)
test('endswith', 'helloworld', 'lowo', 3, 8)
test('endswith', 'ab', 'ab', 0, 1)
test('endswith', 'ab', 'ab', 0, 0)
# TODO: test cases for: int, long, float, complex, +, * and cmp
s = ""
for builtin_method in dir(s):
if not tested_methods.has_key(builtin_method):
print "no regression test case for method '"+builtin_method+"'"
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