Mailman 3 April 2000 - Python-Dev

Re: [Python-Dev] Round Bug in Python 1.6?
by Ka-Ping Yee April 13, 2000

April 13, 2000

Tim Peters wrote: > The best possible IEEE-754 double approximation to 3.1416 is (exactly) > > 3.141599999999999948130380289512686431407928466796875 Let's call this number 'A' for the sake of discussion. > so the output you got is correctly rounded to 17 significant digits. IOW, > it's a feature. Clearly there is something very wrong here: Python 1.5.2+ (#2, Mar 28 2000, 18:27:50) Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam >>> 3.1416 … [View More]

5 14

RE: [Idle-dev] Forward progress with full backward compatibility
by Tim Peters April 13, 2000

April 13, 2000

[Peter Funk] > ... > 2. What should the new Interpreter do, if he sees a source file without a > pragma defining the language level? Python has tens of thousands of users now -- if it doesn't default to "Python 1.5.2" (however that's spelled), approximately 79.681% of them will scream. Had the language done this earlier, it would have been much more sellable to default to the current version. However, a default is *just* "a default", and platform-appropriate config mechanism (… [View More]from Windows registry to cmdline flag) could be introduced to change the default. That is, 1.7 comes out and all my code runs fine without changing a thing. Then I set a global config option to "pretend every module that doesn't say otherwise has a 1.7 pragma in it", and run things again to see what breaks. As part of the process of editing the files that need to be fixed, I can take that natural opportunity to dump in a 1.7 pragma in the modules I've changed, or a 1.6 pragma in the broken modules I can't (for whatever reason) alter just yet. Two pleasant minutes <wink> later, I'll have 6,834 .py files all saying "1.7" at the top. Hmm! So when 1.8 comes out, not a one of them will use any incompatible 1.8 features. So I'll also need a global config option that says "pretend every module has a 1.8 pragma in it, *regardless* of whether it has some other pragma in it already". But that will also screw up the one .py file I forgot that had a 1.5.2 pragma in it. Iterate this process a half dozen times, and I'm afraid the end result is intractable. Seems it would be much more tractable over the long haul to default to the current version. Then every incompatible change will require changing every file that relied on the old behavior (to dump in a "no, I can't use the current version's semantics" pragma) -- but that's the situation today too. The difference is that the minimal change required to get unstuck would be trivial. A nice user (like me <wink>) would devote their life to keeping up with incompatible changes, so would never ever have a version pragma in any file. So I vote "default to current version" -- but, *wow*, that's going to be hard to sell. Tech note: Python's front end is not structured today in such a way that it's feasible to have the parser deal with a change in the set of keywords keying off a pragma -- any given identifier today is either always or never a keyword, and that choice is hardwired into the generated parse tables. Not a reason to avoid starting this process with 1.6, just a reason to avoid adding new keywords in 1.6 (it will take some real work to overcome the front end's limitations here). go-for-it!-ly y'rs - tim [View Less]

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Arbitrary attributes on funcs and methods
by bwarsaw＠python.org April 12, 2000

April 12, 2000

A number of people have played FAST and loose with function and method docstrings, including John Aycock[1], Zope's ORB[2]. Docstrings are handy because they are the one attribute on funcs and methods that are easily writable. But as more people overload the semantics for docstrings, we'll get collisions. I've had a number of discussions with folks about adding attribute dictionaries to functions and methods so that you can essentially add any attribute. Namespaces are one honking great … [View More]idea -- let's do more of those! Below is a very raw set of patches to add an attribute dictionary to funcs and methods. It's only been minimally tested, but if y'all like the idea, I'll clean it up, sanity check the memory management, and post the changes to patches(a)python.org. Here's some things you can do: -------------------- snip snip -------------------- Python 1.6a2 (#10, Apr 10 2000, 11:27:59) [GCC 2.8.1] on sunos5 Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam >>> def a(): pass ... >>> a.publish = 1 >>> a.publish 1 >>> a.__doc__ >>> a.__doc__ = 'a doc string' >>> a.__doc__ 'a doc string' >>> a.magic_string = a.__doc__ >>> a.magic_string 'a doc string' >>> dir(a) ['__doc__', '__name__', 'func_code', 'func_defaults', 'func_dict', 'func_doc', 'func_globals', 'func_name', 'magic_string', 'publish'] >>> class F: ... def a(self): pass ... >>> f = F() >>> f.a.publish Traceback (most recent call last): File "<stdin>", line 1, in ? AttributeError: publish >>> f.a.publish = 1 >>> f.a.publish 1 >>> f.a.__doc__ >>> f.a.__doc__ = 'another doc string' >>> f.a.__doc__ 'another doc string' >>> f.a.magic_string = f.a.__doc__ >>> f.a.magic_string 'another doc string' >>> dir(f.a) ['__dict__', '__doc__', '__name__', 'im_class', 'im_func', 'im_self', 'magic_string', 'publish'] >>> -------------------- snip snip -------------------- -Barry [1] Aycock, "Compiling Little Languages in Python", http://www.foretec.com/python/workshops/1998-11/proceedings/papers/aycock-l… [2] http://classic.zope.org:8080/Documentation/Reference/ORB P.S. I promised to add a little note about setattr and getattr vs. setattro and getattro. There's very little documentation about the differences, and searching on python.org doesn't seem to turn up anything. The differences are simple. setattr/getattr take a char* argument naming the attribute to change, while setattro/getattro take a PyObject* (hence the trailing `o' -- for Object). This stuff should get documented in the C API, but at least now, it'll turn up in a SIG search. :) -------------------- snip snip -------------------- Index: funcobject.h =================================================================== RCS file: /projects/cvsroot/python/dist/src/Include/funcobject.h,v retrieving revision 2.16 diff -c -r2.16 funcobject.h *** funcobject.h 1998/12/04 18:48:02 2.16 --- funcobject.h 2000/04/07 21:30:40 *************** *** 44,49 **** --- 44,50 ---- PyObject *func_defaults; PyObject *func_doc; PyObject *func_name; + PyObject *func_dict; } PyFunctionObject; extern DL_IMPORT(PyTypeObject) PyFunction_Type; Index: classobject.c =================================================================== RCS file: /projects/cvsroot/python/dist/src/Objects/classobject.c,v retrieving revision 2.84 diff -c -r2.84 classobject.c *** classobject.c 2000/04/10 13:03:19 2.84 --- classobject.c 2000/04/10 15:27:15 *************** *** 1550,1577 **** /* Dummies that are not handled by getattr() except for __members__ */ {"__doc__", T_INT, 0}, {"__name__", T_INT, 0}, {NULL} /* Sentinel */ }; static PyObject * instancemethod_getattr(im, name) register PyMethodObject *im; ! PyObject *name; { ! char *sname = PyString_AsString(name); ! if (sname[0] == '_') { /* Inherit __name__ and __doc__ from the callable object implementing the method */ ! if (strcmp(sname, "__name__") == 0 || ! strcmp(sname, "__doc__") == 0) ! return PyObject_GetAttr(im->im_func, name); } if (PyEval_GetRestricted()) { PyErr_SetString(PyExc_RuntimeError, "instance-method attributes not accessible in restricted mode"); return NULL; } ! return PyMember_Get((char *)im, instancemethod_memberlist, sname); } static void --- 1550,1608 ---- /* Dummies that are not handled by getattr() except for __members__ */ {"__doc__", T_INT, 0}, {"__name__", T_INT, 0}, + {"__dict__", T_INT, 0}, {NULL} /* Sentinel */ }; + static int + instancemethod_setattr(im, name, v) + register PyMethodObject *im; + char *name; + PyObject *v; + { + int rtn; + + if (PyEval_GetRestricted() || + strcmp(name, "im_func") == 0 || + strcmp(name, "im_self") == 0 || + strcmp(name, "im_class") == 0) + { + PyErr_Format(PyExc_TypeError, "read-only attribute: %s", name); + return -1; + } + return PyObject_SetAttrString(im->im_func, name, v); + } + + static PyObject * instancemethod_getattr(im, name) register PyMethodObject *im; ! char *name; { ! PyObject *rtn; ! ! if (strcmp(name, "__name__") == 0 || ! strcmp(name, "__doc__") == 0) { /* Inherit __name__ and __doc__ from the callable object implementing the method */ ! return PyObject_GetAttrString(im->im_func, name); } if (PyEval_GetRestricted()) { PyErr_SetString(PyExc_RuntimeError, "instance-method attributes not accessible in restricted mode"); return NULL; + } + if (strcmp(name, "__dict__") == 0) + return PyObject_GetAttrString(im->im_func, name); + + rtn = PyMember_Get((char *)im, instancemethod_memberlist, name); + if (rtn == NULL) { + PyErr_Clear(); + rtn = PyObject_GetAttrString(im->im_func, name); + if (rtn == NULL) + PyErr_SetString(PyExc_AttributeError, name); } ! return rtn; } static void *************** *** 1662,1669 **** 0, (destructor)instancemethod_dealloc, /*tp_dealloc*/ 0, /*tp_print*/ ! 0, /*tp_getattr*/ ! 0, /*tp_setattr*/ (cmpfunc)instancemethod_compare, /*tp_compare*/ (reprfunc)instancemethod_repr, /*tp_repr*/ 0, /*tp_as_number*/ --- 1693,1700 ---- 0, (destructor)instancemethod_dealloc, /*tp_dealloc*/ 0, /*tp_print*/ ! (getattrfunc)instancemethod_getattr, /*tp_getattr*/ ! (setattrfunc)instancemethod_setattr, /*tp_setattr*/ (cmpfunc)instancemethod_compare, /*tp_compare*/ (reprfunc)instancemethod_repr, /*tp_repr*/ 0, /*tp_as_number*/ *************** *** 1672,1678 **** (hashfunc)instancemethod_hash, /*tp_hash*/ 0, /*tp_call*/ 0, /*tp_str*/ ! (getattrofunc)instancemethod_getattr, /*tp_getattro*/ 0, /*tp_setattro*/ }; --- 1703,1709 ---- (hashfunc)instancemethod_hash, /*tp_hash*/ 0, /*tp_call*/ 0, /*tp_str*/ ! 0, /*tp_getattro*/ 0, /*tp_setattro*/ }; Index: funcobject.c =================================================================== RCS file: /projects/cvsroot/python/dist/src/Objects/funcobject.c,v retrieving revision 2.18 diff -c -r2.18 funcobject.c *** funcobject.c 1998/05/22 00:55:34 2.18 --- funcobject.c 2000/04/07 22:15:33 *************** *** 62,67 **** --- 62,68 ---- doc = Py_None; Py_INCREF(doc); op->func_doc = doc; + op->func_dict = PyDict_New(); } return (PyObject *)op; } *************** *** 133,138 **** --- 134,140 ---- {"__name__", T_OBJECT, OFF(func_name), READONLY}, {"func_defaults",T_OBJECT, OFF(func_defaults)}, {"func_doc", T_OBJECT, OFF(func_doc)}, + {"func_dict", T_OBJECT, OFF(func_dict)}, {"__doc__", T_OBJECT, OFF(func_doc)}, {NULL} /* Sentinel */ }; *************** *** 142,153 **** PyFunctionObject *op; char *name; { if (name[0] != '_' && PyEval_GetRestricted()) { PyErr_SetString(PyExc_RuntimeError, "function attributes not accessible in restricted mode"); return NULL; } ! return PyMember_Get((char *)op, func_memberlist, name); } static int --- 144,167 ---- PyFunctionObject *op; char *name; { + PyObject* rtn; + if (name[0] != '_' && PyEval_GetRestricted()) { PyErr_SetString(PyExc_RuntimeError, "function attributes not accessible in restricted mode"); return NULL; + } + if (strcmp(name, "__dict__") == 0) + return op->func_dict; + + rtn = PyMember_Get((char *)op, func_memberlist, name); + if (rtn == NULL) { + PyErr_Clear(); + rtn = PyDict_GetItemString(op->func_dict, name); + if (rtn == NULL) + PyErr_SetString(PyExc_AttributeError, name); } ! return rtn; } static int *************** *** 156,161 **** --- 170,177 ---- char *name; PyObject *value; { + int rtn; + if (PyEval_GetRestricted()) { PyErr_SetString(PyExc_RuntimeError, "function attributes not settable in restricted mode"); *************** *** 178,185 **** } if (value == Py_None) value = NULL; } ! return PyMember_Set((char *)op, func_memberlist, name, value); } static void --- 194,214 ---- } if (value == Py_None) value = NULL; + } + else if (strcmp(name, "func_dict") == 0) { + if (value == NULL || !PyDict_Check(value)) { + PyErr_SetString( + PyExc_TypeError, + "func_dict must be set to a dict object"); + return -1; + } + } + rtn = PyMember_Set((char *)op, func_memberlist, name, value); + if (rtn < 0) { + PyErr_Clear(); + rtn = PyDict_SetItemString(op->func_dict, name, value); } ! return rtn; } static void *************** *** 191,196 **** --- 220,226 ---- Py_DECREF(op->func_name); Py_XDECREF(op->func_defaults); Py_XDECREF(op->func_doc); + Py_XDECREF(op->func_dict); PyMem_DEL(op); } [View Less]

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re: #pragmas and method attributes
by gvwilson＠nevex.com April 12, 2000

April 12, 2000

> > On Wed, 12 Apr 2000, Paul Prescod wrote: > > About a month ago I wrote (but did not publish) a proposal that combined > > #pragmas and method attributes. The reason I combined them is that in a > > lot of cases method "attributes" are supposed to be available in the > > parse tree, before the program begins to run. Here is my rough draft. > Moshe Zadka wrote: > BTW: Why force the value to be a string? Any immutable basic type > should do fine, no?? … [View More]

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Processing XML with Perl (interesting article) (fwd)
by gvwilson＠nevex.com April 12, 2000

April 12, 2000

http://www.xml.com/pub/2000/04/05/feature/index.html is Michael Rodriguez' summary of XML processing modules for Perl. It opens with: "Perl is one of the most powerful (and even the most devout Python zealots will agree here) and widely used text processing languages." Greg

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Second round: arbitrary function and method attributes
by Barry A. Warsaw April 12, 2000

April 12, 2000

Here's the second go at adding arbitrary attribute support to function and method objects. Note that this time it's illegal (TypeError) to set an attribute on a bound method object; getting an attribute on a bound method object returns the value on the underlying function object. First the diffs, then the test case and test output. Enjoy, -Barry Index: Include/funcobject.h =================================================================== RCS file: /projects/cvsroot/python/dist/src/… [View More]Include/funcobject.h,v retrieving revision 2.16 diff -u -r2.16 funcobject.h --- funcobject.h 1998/12/04 18:48:02 2.16 +++ funcobject.h 2000/04/07 21:30:40 @@ -44,6 +44,7 @@ PyObject *func_defaults; PyObject *func_doc; PyObject *func_name; + PyObject *func_dict; } PyFunctionObject; extern DL_IMPORT(PyTypeObject) PyFunction_Type; Index: Objects/classobject.c =================================================================== RCS file: /projects/cvsroot/python/dist/src/Objects/classobject.c,v retrieving revision 2.84 diff -u -r2.84 classobject.c --- classobject.c 2000/04/10 13:03:19 2.84 +++ classobject.c 2000/04/11 22:05:08 @@ -1550,28 +1550,75 @@ /* Dummies that are not handled by getattr() except for __members__ */ {"__doc__", T_INT, 0}, {"__name__", T_INT, 0}, + {"__dict__", T_INT, 0}, {NULL} /* Sentinel */ }; +static int +instancemethod_setattro(im, name, v) + register PyMethodObject *im; + PyObject *name; + PyObject *v; +{ + char* sname = PyString_AsString(name); + if (sname == NULL) + return -1; + + if (PyEval_GetRestricted() || + strcmp(sname, "im_func") == 0 || + strcmp(sname, "im_self") == 0 || + strcmp(sname, "im_class") == 0) + { + PyErr_Format(PyExc_TypeError, "read-only attribute: %s", sname); + return -1; + } + if (im->im_self != NULL) { + PyErr_Format(PyExc_TypeError, + "cannot set bound instance-method attribute: %s", + sname); + return -1; + } + return PyObject_SetAttr(im->im_func, name, v); +} + + static PyObject * -instancemethod_getattr(im, name) +instancemethod_getattro(im, name) register PyMethodObject *im; PyObject *name; { - char *sname = PyString_AsString(name); + PyObject *rtn; + char* sname = PyString_AsString(name); + + if (sname == NULL) + return NULL; + if (sname[0] == '_') { /* Inherit __name__ and __doc__ from the callable object - implementing the method */ - if (strcmp(sname, "__name__") == 0 || - strcmp(sname, "__doc__") == 0) + implementing the method. Can't allow access to __dict__ + here because it should not be readable in restricted + execution mode. + */ + if (strcmp(sname, "__name__") == 0 || + strcmp(sname, "__doc__") == 0) { return PyObject_GetAttr(im->im_func, name); + } } if (PyEval_GetRestricted()) { - PyErr_SetString(PyExc_RuntimeError, - "instance-method attributes not accessible in restricted mode"); + PyErr_Format(PyExc_RuntimeError, + "instance-method attributes not accessible in restricted mode: %s", + sname); return NULL; + } + if (sname[0] == '_' && strcmp(sname, "__dict__") == 0) + return PyObject_GetAttr(im->im_func, name); + + rtn = PyMember_Get((char *)im, instancemethod_memberlist, sname); + if (rtn == NULL) { + PyErr_Clear(); + rtn = PyObject_GetAttr(im->im_func, name); } - return PyMember_Get((char *)im, instancemethod_memberlist, sname); + return rtn; } static void @@ -1672,8 +1719,8 @@ (hashfunc)instancemethod_hash, /*tp_hash*/ 0, /*tp_call*/ 0, /*tp_str*/ - (getattrofunc)instancemethod_getattr, /*tp_getattro*/ - 0, /*tp_setattro*/ + (getattrofunc)instancemethod_getattro, /*tp_getattro*/ + (setattrofunc)instancemethod_setattro, /*tp_setattro*/ }; /* Clear out the free list */ Index: Objects/funcobject.c =================================================================== RCS file: /projects/cvsroot/python/dist/src/Objects/funcobject.c,v retrieving revision 2.18 diff -u -r2.18 funcobject.c --- funcobject.c 1998/05/22 00:55:34 2.18 +++ funcobject.c 2000/04/11 22:06:12 @@ -62,6 +62,7 @@ doc = Py_None; Py_INCREF(doc); op->func_doc = doc; + op->func_dict = PyDict_New(); } return (PyObject *)op; } @@ -133,6 +134,8 @@ {"__name__", T_OBJECT, OFF(func_name), READONLY}, {"func_defaults",T_OBJECT, OFF(func_defaults)}, {"func_doc", T_OBJECT, OFF(func_doc)}, + {"func_dict", T_OBJECT, OFF(func_dict)}, + {"__dict__", T_OBJECT, OFF(func_dict)}, {"__doc__", T_OBJECT, OFF(func_doc)}, {NULL} /* Sentinel */ }; @@ -142,12 +145,21 @@ PyFunctionObject *op; char *name; { + PyObject* rtn; + if (name[0] != '_' && PyEval_GetRestricted()) { PyErr_SetString(PyExc_RuntimeError, "function attributes not accessible in restricted mode"); return NULL; + } + rtn = PyMember_Get((char *)op, func_memberlist, name); + if (rtn == NULL) { + PyErr_Clear(); + rtn = PyMapping_GetItemString(op->func_dict, name); + if (rtn == NULL) + PyErr_SetString(PyExc_AttributeError, name); } - return PyMember_Get((char *)op, func_memberlist, name); + return rtn; } static int @@ -156,6 +168,8 @@ char *name; PyObject *value; { + int rtn; + if (PyEval_GetRestricted()) { PyErr_SetString(PyExc_RuntimeError, "function attributes not settable in restricted mode"); @@ -178,8 +192,23 @@ } if (value == Py_None) value = NULL; + } + else if (strcmp(name, "func_dict") == 0 || + strcmp(name, "__dict__") == 0) + { + if (value == NULL || !PyMapping_Check(value)) { + PyErr_SetString( + PyExc_TypeError, + "must set func_dict to a mapping object"); + return -1; + } + } + rtn = PyMember_Set((char *)op, func_memberlist, name, value); + if (rtn < 0) { + PyErr_Clear(); + rtn = PyMapping_SetItemString(op->func_dict, name, value); } - return PyMember_Set((char *)op, func_memberlist, name, value); + return rtn; } static void @@ -191,6 +220,7 @@ Py_DECREF(op->func_name); Py_XDECREF(op->func_defaults); Py_XDECREF(op->func_doc); + Py_XDECREF(op->func_dict); PyMem_DEL(op); } from test_support import verbose class F: def a(self): pass def b(): pass # setting attributes on functions try: b.blah except AttributeError: pass else: print 'did not get expected AttributeError' b.blah = 1 print b.blah == 1 print 'blah' in dir(b) # setting attributes on unbound methods try: F.a.blah except AttributeError: pass else: print 'did not get expected AttributeError' F.a.blah = 1 print F.a.blah == 1 print 'blah' in dir(F.a) # setting attributes on bound methods is illegal f1 = F() try: f1.a.snerp = 1 except TypeError: pass else: print 'did not get expected TypeError' # but accessing attributes on bound methods is fine print f1.a.blah print 'blah' in dir(f1.a) f2 = F() print f1.a.blah == f2.a.blah F.a.wazoo = F f1.a.wazoo is f2.a.wazoo # try setting __dict__ illegally try: F.a.__dict__ = (1, 2, 3) except TypeError: pass else: print 'did not get expected TypeError' F.a.__dict__ = {'one': 111, 'two': 222, 'three': 333} print f1.a.two == 222 from UserDict import UserDict d = UserDict({'four': 444, 'five': 555}) F.a.__dict__ = d try: f2.a.two except AttributeError: pass else: print 'did not get expected AttributeError' print f2.a.four is f1.a.four is F.a.four test_funcattrs 1 1 1 1 1 1 1 1 1 [View Less]

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UTF-8 is no fun...
by Andy Robinson April 12, 2000

April 12, 2000

> > Things are hard to get right when you have to deal with > > backward *and* forward compatibility, interoperability and > > user-friendliness all at the same time... but we'll keep > > trying ;-) > > Let me say publically that I think you have done a fine job, and > obviously have put lots of thought and effort into it. If parts of > the design turn out to be less than ideal (and subsequently changed > before 1.6 is real) then this will not detract … [View More]

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The purpose of the 'repr' builtin function
by pf＠artcom-gmbh.de April 12, 2000

April 12, 2000

Hi! Currently the wrapper classes UserList und UserString contain the following method: def __repr__(self): return repr(self.data) I wonder about the following alternatives: def __repr__(self): return self.__class__.__name__ + "(" + repr(self.data) + ")" or even more radical (here only for lists as an example): def __repr__(self): result = [self.__class__.__name__, "("] for item in self.data: result.append(repr(item)) result.… [View More]

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Extensible library packages
by Andrew M. Kuchling April 12, 2000

April 12, 2000

For 1.6, the XML-SIG wants to submit a few more things, mostly a small SAX implementation. This currently lives in xml.sax.*. There are other subpackages around such as xml.dom, xml.utils, and so forth, but those aren't being proposed for inclusion (too large, too specialized, or whatever reason). The problem is that, if the Python standard library includes a package named 'xml', that package name can't be extended by add-on modules (unless they install themselves into Python's library … [View More]

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Re: ANNOUNCE: Python 1.6 alpha 2
by Jonathan Giddy April 11, 2000

April 11, 2000

Bill Janssen declared: > >ILU seems to work fine with it. > >Bill Without wishing to jinx this good news, isn't the release of 1.6 the appropriate time to remove the redundant thread.h file? Jon.

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