Package: python2.4 Version: 2.4.2-2 Severity: normal
There seems to be a bug in classes derived from float. For instance, consider the following: >>> class Float(float): ... def __init__(self, v): ... float.__init__(self, v) ... self.x = 1 ... >>> a = Float(2.0) >>> b = Float(3.0) >>> type(a) <class '__main__.Float'> >>> type(b) <class '__main__.Float'> >>> a += b >>> type(a) <type 'float'> Now, the type of a has silently changed. It was a Float, a derived class with all kinds of properties, and it became a float -- a plain vanilla number. My understanding is that this is incorrect, and certainly unexpected. If it *is* correct, it certainly deserves mention somewhere in the documentation. It seems that Float.__iadd__(a, b) should be called. This defaults to float.__iadd__(a, b), which should increment the float part of the object while leaving the rest intact. A possible explanation for this problem is that float.__iadd__ is not actually defined, and so it falls through to a = float.__add__(a, b), which assigns a float to a. This interpretation seems to be correct, as one can add a destructor to the Float class: >>> class FloatD(float): ... def __init__(self, v): ... float.__init__(self, v) ... self.x = 1 ... def __del__(self): ... print 'Deleting FloatD class, losing x=', self.x ... >>> a = FloatD(2.0) >>> b = FloatD(3.0) >>> a += b Deleting FloatD class, losing x= 1 >>> -- System Information: Debian Release: testing/unstable APT prefers testing APT policy: (500, 'testing') Architecture: i386 (i686) Shell: /bin/sh linked to /bin/bash Kernel: Linux 2.6.12-1-686 Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968) Versions of packages python2.4 depends on: ii libbz2-1.0 1.0.2-11 high-quality block-sorting file co ii libc6 2.3.5-8 GNU C Library: Shared libraries an ii libdb4.3 4.3.29-3 Berkeley v4.3 Database Libraries [ ii libncurses5 5.5-1 Shared libraries for terminal hand ii libreadline5 5.0-11 GNU readline and history libraries ii libssl0.9.8 0.9.8a-3 SSL shared libraries ii python2.4-minimal 2.4.2-2 A minimal subset of the Python lan python2.4 recommends no packages. -- no debconf information -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
