Mailman 3 June 2006 - Python-checkins

r47086 - in python/trunk: Misc/NEWS Python/codecs.c
by hyeshik.chang 06 Jul '06

06 Jul '06

Author: hyeshik.chang Date: Fri Jun 23 23:16:18 2006 New Revision: 47086 Modified: python/trunk/Misc/NEWS python/trunk/Python/codecs.c Log: Bug #1511381: codec_getstreamcodec() in codec.c is corrected to omit a default "error" argument for NULL pointer. This allows the parser to take a codec from cjkcodecs again. (Reported by Taewook Kang and reviewed by Walter Doerwald) Modified: python/trunk/Misc/NEWS ============================================================================== --- python/trunk/Misc/NEWS (original) +++ python/trunk/Misc/NEWS Fri Jun 23 23:16:18 2006 @@ -12,6 +12,9 @@ Core and builtins ----------------- +- Bug #1511381: codec_getstreamcodec() in codec.c is corrected to + omit a default "error" argument for NULL pointer. This allows + the parser to take a codec from cjkcodecs again. Library ------- Modified: python/trunk/Python/codecs.c ============================================================================== --- python/trunk/Python/codecs.c (original) +++ python/trunk/Python/codecs.c Fri Jun 23 23:16:18 2006 @@ -249,14 +249,17 @@ const char *errors, const int index) { - PyObject *codecs, *streamcodec; + PyObject *codecs, *streamcodec, *codeccls; codecs = _PyCodec_Lookup(encoding); if (codecs == NULL) return NULL; - streamcodec = PyEval_CallFunction( - PyTuple_GET_ITEM(codecs, index), "Os", stream, errors); + codeccls = PyTuple_GET_ITEM(codecs, index); + if (errors != NULL) + streamcodec = PyObject_CallFunction(codeccls, "Os", stream, errors); + else + streamcodec = PyObject_CallFunction(codeccls, "O", stream); Py_DECREF(codecs); return streamcodec; }

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r46894 - in python/trunk: Modules/timemodule.c Objects/exceptions.c Objects/fileobject.c
by kristjan.jonsson 01 Jul '06

01 Jul '06

Author: kristjan.jonsson Date: Mon Jun 12 17:45:12 2006 New Revision: 46894 Modified: python/trunk/Modules/timemodule.c python/trunk/Objects/exceptions.c python/trunk/Objects/fileobject.c Log: Fix the CRT argument error handling for VisualStudio .NET 2005. Install a CRT error handler and disable the assertion for debug builds. This causes CRT to set errno to EINVAL. This update fixes crash cases in the test suite where the default CRT error handler would cause process exit. Modified: python/trunk/Modules/timemodule.c ============================================================================== --- python/trunk/Modules/timemodule.c (original) +++ python/trunk/Modules/timemodule.c Mon Jun 12 17:45:12 2006 @@ -467,6 +467,14 @@ return ret; } free(outbuf); +#if defined _MSC_VER && _MSC_VER >= 1400 + /* VisualStudio .NET 2005 does this properly */ + if (buflen == 0 && errno == EINVAL) { + PyErr_SetString(PyExc_ValueError, "Invalid format string"); + return 0; + } +#endif + } } Modified: python/trunk/Objects/exceptions.c ============================================================================== --- python/trunk/Objects/exceptions.c (original) +++ python/trunk/Objects/exceptions.c Mon Jun 12 17:45:12 2006 @@ -1967,6 +1967,29 @@ if (PyDict_SetItemString(bdict, # TYPE, PyExc_ ## TYPE)) \ Py_FatalError("Module dictionary insertion problem."); +#if defined _MSC_VER && _MSC_VER >= 1400 +/* crt variable checking in VisualStudio .NET 2005 */ +#include <crtdbg.h> + +static int prevCrtReportMode; +static _invalid_parameter_handler prevCrtHandler; + +/* Invalid parameter handler. Sets a ValueError exception */ +static void +InvalidParameterHandler( + const wchar_t * expression, + const wchar_t * function, + const wchar_t * file, + unsigned int line, + uintptr_t pReserved) +{ + /* Do nothing, allow execution to continue. Usually this + * means that the CRT will set errno to EINVAL + */ +} +#endif + + PyMODINIT_FUNC _PyExc_Init(void) { @@ -2096,6 +2119,13 @@ Py_FatalError("Cannot pre-allocate MemoryError instance\n"); Py_DECREF(bltinmod); + +#if defined _MSC_VER && _MSC_VER >= 1400 + /* Set CRT argument error handler */ + prevCrtHandler = _set_invalid_parameter_handler(InvalidParameterHandler); + /* turn off assertions in debug mode */ + prevCrtReportMode = _CrtSetReportMode(_CRT_ASSERT, 0); +#endif } void @@ -2103,4 +2133,9 @@ { Py_XDECREF(PyExc_MemoryErrorInst); PyExc_MemoryErrorInst = NULL; +#if defined _MSC_VER && _MSC_VER >= 1400 + /* reset CRT error handling */ + _set_invalid_parameter_handler(prevCrtHandler); + _CrtSetReportMode(_CRT_ASSERT, prevCrtReportMode); +#endif } Modified: python/trunk/Objects/fileobject.c ============================================================================== --- python/trunk/Objects/fileobject.c (original) +++ python/trunk/Objects/fileobject.c Mon Jun 12 17:45:12 2006 @@ -241,13 +241,15 @@ } if (f->f_fp == NULL) { -#ifdef _MSC_VER +#if defined _MSC_VER && _MSC_VER < 1400 /* MSVC 6 (Microsoft) leaves errno at 0 for bad mode strings, * across all Windows flavors. When it sets EINVAL varies * across Windows flavors, the exact conditions aren't * documented, and the answer lies in the OS's implementation * of Win32's CreateFile function (whose source is secret). * Seems the best we can do is map EINVAL to ENOENT. + * Starting with Visual Studio .NET 2005, EINVAL is correctly + * set by our CRT error handler (set in exceptions.c.) */ if (errno == 0) /* bad mode string */ errno = EINVAL;

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r47185 - sandbox/trunk/Doc/functional.rst
by andrew.kuchling 30 Jun '06

30 Jun '06

Author: andrew.kuchling Date: Fri Jun 30 23:41:11 2006 New Revision: 47185 Modified: sandbox/trunk/Doc/functional.rst Log: Typo fix Modified: sandbox/trunk/Doc/functional.rst ============================================================================== --- sandbox/trunk/Doc/functional.rst (original) +++ sandbox/trunk/Doc/functional.rst Fri Jun 30 23:41:11 2006 @@ -363,7 +363,7 @@ stripped_list = [line.strip() for line in line_list if line != ""] -Note that in all case the resulting ``stripped_list`` is a Python list +Note that in all cases the resulting ``stripped_list`` is a Python list containing the resulting lines, not an iterator. This means that list comprehensions aren't very useful if you're working with iterators that return an infinite or a very large stream of data. Later we'll

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r47184 - sandbox/trunk/Doc/functional.rst
by andrew.kuchling 30 Jun '06

30 Jun '06

Author: andrew.kuchling Date: Fri Jun 30 23:16:06 2006 New Revision: 47184 Modified: sandbox/trunk/Doc/functional.rst Log: Add version; note reservation about URL; add history Modified: sandbox/trunk/Doc/functional.rst ============================================================================== --- sandbox/trunk/Doc/functional.rst (original) +++ sandbox/trunk/Doc/functional.rst Fri Jun 30 23:16:06 2006 @@ -1,8 +1,12 @@ Functional Programming HOWTO ================================ +**Version 0.1** + (This is a first draft. Please send comments/error -reports/suggestions to amk(a)amk.ca.) +reports/suggestions to amk(a)amk.ca. This URL is probably not going to +be the final location of the document, so be careful about linking to +it -- you may want to add a disclaimer.) In this document, we'll take a tour of Python's features suitable for implementing programs in a functional style. After an introduction to @@ -1124,13 +1128,14 @@ server_log('Unable to open socket') -Acknowledgements ------------------------------- +Revision History and Acknowledgements +------------------------------------------------ The author would like to thank the following people for offering suggestions, corrections and assistance with various drafts of this article: Raymond Hettinger, Jim Jewett. +Version 0.1: posted June 30 2006. .. comment

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Python Regression Test Failures refleak (1)
by Neal Norwitz 30 Jun '06

30 Jun '06

test_socket leaked [212, -212, 0] references

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buildbot warnings in alpha Debian trunk
by buildbot＠python.org 30 Jun '06

30 Jun '06

The Buildbot has detected a new failure of alpha Debian trunk. Full details are available at: http://www.python.org/dev/buildbot/all/alpha%2520Debian%2520trunk/builds/436 Buildbot URL: http://www.python.org/dev/buildbot/all/ Build Reason: Build Source Stamp: [branch trunk] HEAD Blamelist: tim.peters Build Had Warnings: warnings test sincerely, -The Buildbot

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r47183 - sandbox/trunk/Doc/functional.rst
by andrew.kuchling 30 Jun '06

30 Jun '06

Author: andrew.kuchling Date: Fri Jun 30 23:03:11 2006 New Revision: 47183 Modified: sandbox/trunk/Doc/functional.rst Log: Revision pass: lots of small edits; request feedback; remove LaTeX markup :) ; add small references section Modified: sandbox/trunk/Doc/functional.rst ============================================================================== --- sandbox/trunk/Doc/functional.rst (original) +++ sandbox/trunk/Doc/functional.rst Fri Jun 30 23:03:11 2006 @@ -1,13 +1,14 @@ Functional Programming HOWTO ================================ -**Incomplete Draft** +(This is a first draft. Please send comments/error +reports/suggestions to amk(a)amk.ca.) -In this document, we'll take a tour of Python's features that are -well-suited to implementing programs in a functional style. After an -introduction to the concepts of functional programming, we'll look at -language features such as iterators and generators and relevant -library modules such as the ``itertools`` and ``functools`` modules. +In this document, we'll take a tour of Python's features suitable for +implementing programs in a functional style. After an introduction to +the concepts of functional programming, we'll look at language +features such as iterators and generators and relevant library modules +such as ``itertools`` and ``functools``. Introduction @@ -20,10 +21,11 @@ Programming languages support decomposing problems in several different ways: -* Most programming languages are **procedural**, meaning - that programs are lists of instructions that tell the computer what to - do with the program's input. - C, Pascal, and even Unix shells are procedural languages. +* Most programming languages are **procedural**: + programs are lists of instructions that tell the computer what to + do with the program's input. + C, Pascal, and even Unix shells are procedural languages. + * In **declarative** languages, you write a specification that describes the problem to be solved, and the language implementation figures out how to perform the computation efficiently. SQL is the declarative @@ -31,43 +33,54 @@ the data set you want to retrieve, and the SQL engine decides whether to scan tables or use indexes, which subclauses should be performed first, etc. -* **Object-oriented** programming is a style in which programs consist - of collections of objects. Objects have internal state and support various - methods that query or modify this internal state in some way. Smalltalk - and Java are object-oriented languages. C++ and Python are languages - that support object-oriented programming, but don't require it. + +* **Object-oriented** programs manipulate collections of objects. + Objects have internal state and support methods that query or modify + this internal state in some way. Smalltalk and Java are + object-oriented languages. C++ and Python are languages that + support object-oriented programming, but don't force the use + of object-oriented features. + * **Functional** programming decomposes a problem into a set of functions. Ideally, functions only take inputs and produce outputs, and don't have any internal state that affects the output produced for a given input. Well-known functional languages include the ML family (Standard ML, - OCaml, and other variants) and Haskell. + OCaml, and other variants) and Haskell. -The designers of some computer languages have chosen one style of -programming that they support best. This often makes it difficult to -write programs in the language that use a different style. Other -language designers try to produce multi-paradigm languages that -support several different styles. Lisp, C++, and Python are -multi-paradigm; you can write programs or libraries that are largely -procedural, object-oriented, or functional. In a large program, -different sections might be written in different styles; the GUI might -be object-oriented while the processing logic is procedural or -functional, for example. +The designers of some computer languages have chosen one approach to +programming that's emphasized. This often makes it difficult to +write programs that use a different approach. Other languages are +multi-paradigm languages that support several different approaches. Lisp, +C++, and Python are multi-paradigm; you can write programs or +libraries that are largely procedural, object-oriented, or functional +in all of these languages. In a large program, different sections +might be written using different approaches; the GUI might be object-oriented +while the processing logic is procedural or functional, for example. In a functional program, input flows through a set of functions. Each function operates on its input and produces some output. Functional -style avoids making functions have side effects that modify internal +style frowns upon functions with side effects that modify internal state or make other changes that aren't visible in the function's -return value. Avoiding side effects means not using data structures -that get updated as a program runs. Some languages are very strict -about this and don't even have assignment statements such as ``a=3`` -or ``c = a + b``, but it's difficult to avoid all side effects; some -Python code, such as a ``print`` statement or a ``time.sleep(1)``, -returns nothing and is only called for its side effects. +return value. Functions that have no side effects at all are +called **purely functional**. +Avoiding side effects means not using data structures +that get updated as a program runs; every function's output +must only depend on its input. + +Some languages are very strict about purity and don't even have +assignment statements such as ``a=3`` or ``c = a + b``, but it's +difficult to avoid all side effects. Printing to the screen or +writing to a disk file are side effects, for example. For example, in +Python a ``print`` statement or a ``time.sleep(1)`` both return no +useful value; they're only called for their side effects of sending +some text to the screen or pausing execution for a second. Python programs written in functional style usually won't go to the -extreme of avoiding all I/O or all assignments. The implementation of -a function will still use assignments to local variables, but won't -touch any global variables or have other side effects. +extreme of avoiding all I/O or all assignments; instead, they'll +provide a functional-appearing interface but will use non-functional +features internally. For example, the implementation of a function +will still use assignments to local variables, but won't modify global +variables or have other side effects. Functional programming can be considered the opposite of object-oriented programming. Objects are little capsules containing @@ -122,29 +135,30 @@ you use daily (the Python interpreter, your XML parser, your web browser) could be proven correct. Even if you wrote down or generated a proof, there would then be the question of verifying the proof; -maybe you only ***think*** you've proved that the program correct. +maybe there's an error in it, and you only ***think*** you've proved +that the program correct. Modularity '''''''''''''''''''''' A more practical benefit of functional programming is that it forces -you to break apart your problem into small pieces. It's easier to -specify and write a small function that does one thing than a large -function that performs a complicated transformation. Small functions -are easier to read and to check for errors. A program that's -structured into many small pieces is a **modular** program. +you to break apart your problem into small pieces. Programs are more +modular as a result. It's easier to specify and write a small +function that does one thing than a large function that performs a +complicated transformation. Small functions are also easier to read +and to check for errors. Ease of debugging and testing '''''''''''''''''''''''''''''''''' -It's also easier to test and to debug a functional-style program. +Testing and debugging a functional-style program is easier. -It's easier to debug because functions are generally small and clearly -specified. When a program doesn't work, each function is an interface -point where you can check that the data is correct. You can look at -the intermediate inputs and outputs to quickly isolate the function -that's responsible for a bug. +Debugging is simplified because functions are generally small and +clearly specified. When a program doesn't work, each function is an +interface point where you can check that the data are correct. You +can look at the intermediate inputs and outputs to quickly isolate the +function that's responsible for a bug. Testing is easier because each function is a potential subject for a unit test. Functions don't depend on system state that needs to be @@ -162,7 +176,7 @@ others will be useful in a wide variety of programs. For example, a function that takes a directory path and returns all the XML files in the directory, or a function that takes a filename and returns its -contents would be useful in many different situations. +contents, can be applied to many different situations. Over time you'll form a personal library of utilities. Often you'll assemble new programs by arranging existing functions in a new @@ -171,18 +185,17 @@ - Iterators ----------------------- -Iterators are an important foundation for writing functional-style -programs. +I'll start by looking at a Python language feature that's an important +foundation for writing functional-style programs: iterators. -An iterator is an object representing a stream of data that returns -the data one element at a time. A Python iterator must support a -method called ``next()`` that takes no arguments and always returns -the next element of the stream. If there are no more elements in the -stream, ``next()`` must raise the ``StopIteration`` exception. +An iterator is an object representing a stream of data; this object +returns the data one element at a time. A Python iterator must +support a method called ``next()`` that takes no arguments and always +returns the next element of the stream. If there are no more elements +in the stream, ``next()`` must raise the ``StopIteration`` exception. Iterators don't have to be finite, though; it's perfectly reasonable to write an iterator that produces an infinite stream of data. @@ -190,7 +203,8 @@ to return an iterator that will return the object's contents or elements, raising ``TypeError`` if the object doesn't support iteration. Several of Python's built-in data types support iteration, -the most common being lists and dictionaries. +the most common being lists and dictionaries. An object is called +an **iterable** object if you can get an iterator for it. You can experiment with the iteration interface manually:: @@ -221,8 +235,8 @@ for i in obj: print i -Iterators can be materialized as lists or tuples by using the ``list()`` or ``tuple()`` -constructor functions:: +Iterators can be materialized as lists or tuples by using the +``list()`` or ``tuple()`` constructor functions:: >>> L = [1,2,3] >>> iterator = iter(L) @@ -285,10 +299,14 @@ Dec 12 Oct 10 -This is just the default behaviour. If you want to iterate over keys, -values, or key/value pairs, you can explicitly call the -``iterkeys()``, ``itervalues()``, or ``iteritems()`` -methods to get an appropriate iterator. +Note that the order is essentially random, because it's based on the +hash ordering of the objects in the dictionary. + +Applying ``iter()`` to a dictionary always loops over the keys, but +dictionaries have methods that return other iterators. If you want to +iterate over keys, values, or key/value pairs, you can explicitly call +the ``iterkeys()``, ``itervalues()``, or ``iteritems()`` methods to +get an appropriate iterator. The ``dict()`` constructor can accept an iterator that returns a finite stream of ``(key, value)`` tuples:: @@ -317,10 +335,15 @@ List comprehensions ----------------------- +.. comment + + Maybe gencomps should be described and emphasized, and listcomps + be mentioned as an afterthought. + Two common operations on a stream are performing some operation for every element, or selecting a subset of elements that meet some condition. For example, given a list of strings, you might want to -pull out all the strings containing a given substring, or strip off +pull out all the strings containing a given substring or strip off trailing whitespace from each line. List comprehensions (or "listcomps") are a concise notation for such @@ -340,9 +363,8 @@ containing the resulting lines, not an iterator. This means that list comprehensions aren't very useful if you're working with iterators that return an infinite or a very large stream of data. Later we'll -discuss generator expressions, a feature that provides similar -capabilities as list comprehensions but can be used with infinite -iterators. +discuss generator expressions, which have the capabilities of list +comprehensions but can be used with infinite iterators. List comprehensions have the form:: @@ -403,8 +425,8 @@ ----------------------- Generator expressions are written like list comprehensions, but are -surrounded by parentheses (\samp{()}) and not square brackets -(\samp{[]}). The result of a generator expression +surrounded by parentheses ("()") and not square brackets +("[]"). The result of a generator expression is an iterator that returns the computed elements without materializing a list containing them all. @@ -520,7 +542,7 @@ -New generator features in Python 2.5 +Passing values into a generator '''''''''''''''''''''''''''''''''''''''''''''' In Python 2.4 and earlier, generators only produced output. Once a @@ -625,8 +647,7 @@ Built-in functions ---------------------------------------------- -Let's look in more detail at those built-in functions that are -relevant to iterators. +Let's look in more detail at built-in functions often used with iterators. Two Python's built-in functions, ``map()`` and ``filter()``, are somewhat obsolete; they duplicate the features of list comprehensions @@ -701,7 +722,7 @@ If you use ``operator.add`` with ``reduce()``, you'll add up all the elements of the iterable. This case is so common that there's a special -built-in for it:: +built-in called ``sum()`` to compute it:: reduce(operator.add, [1,2,3,4], 0) => 10 @@ -710,8 +731,20 @@ sum([]) => 0 -``enumerate(iter)`` counts off the elements in the iterable, return -pairs of the count and each element. +For many uses of ``reduce()``, though, it can be clearer to just write +the obvious ``for`` loop:: + + # Instead of: + product = reduce(operator.mul, [1,2,3], 1) + + # You can write: + product = 1 + for i in [1,2,3]: + product *= i + + +``enumerate(iter)`` counts off the elements in the iterable, returning +2-tuples containing the count and each element. :: @@ -724,7 +757,7 @@ f = open('data.txt', 'r') for i, line in enumerate(f): if line.strip() == '': - print 'Blank line at', line + print 'Blank line at line #%i' % i ``sorted(iterable, [cmp=None], [key=None], [reverse=False)`` collects all the elements of the iterable into a list, sorts @@ -745,12 +778,12 @@ [9878, 9828, 8442, 7953, 6431, 6213, 2207, 769] (For a more detailed discussion of sorting, see the Sorting mini-HOWTO -in the Python wiki at \url{http://wiki.python.org/moin/SortingHowto}.) +in the Python wiki at http://wiki.python.org/moin/SortingHowto.) The ``any(iter)`` and ``all(iter)`` built-ins look at the truth values of an iterable's contents. ``any()`` returns True if any element in the iterable is a true value, and ``all()`` -retturn True if all of the elements are true values:: +returns True if all of the elements are true values:: any([0,1,0]) => True @@ -770,16 +803,13 @@ ---------------------------------------------- When writing functional-style programs, you'll often need little -functions that act as predicates or that combine list elements in some -particular way. +functions that act as predicates or that combine elements in some way. -If there's a Python built-in that's suitable, or a module has a -function that does what you need, you don't need to define a new -function at all:: +If there's a Python built-in or a module function that's suitable, you +don't need to define a new function at all:: stripped_lines = [line.strip for line in lines] existing_files = filter(os.path.exists, file_list) - XXX pi-notation example If the function you need doesn't exist, you need to write it. One way to write small functions is to use the ``lambda`` statement. ``lambda`` @@ -804,7 +834,8 @@ def adder(x,y): return x + y -Which alternative is preferable? That's a style question. +Which alternative is preferable? That's a style question; my general +view is to avoid it. ``lambda`` is quite limited in the functions it can define. The result has to be computable as a single expression, which means you @@ -815,7 +846,22 @@ :: - freq = reduce(lambda a, b: (0, a[1] + b[1]), items)[1] + freq = reduce(lambda a, b: (0, a[1] + b[1]), items)[1] + +You can figure it out, but it takes time to disentangle the function +to figure out what's going on. Using a short nested +``def`` statements makes things a little bit better:: + + def combine (a, b): + return 0, a[1] + b[1] + + return reduce(combine_freq, items)[1] + +It would be best of all if I had simply used a ``for`` loop:: + + total = 0 + for a, b in items: + total += b Fredrik Lundh once suggested the following set of rules for refactoring uses of ``lambda``: @@ -827,28 +873,16 @@ 4) Convert the lambda to a def statement, using that name. 5) Remove the comment. -Personally I try to avoid lambdas, favoring short nested -``def`` statements like this:: - - def output_total_freq (items): - """Takes a list of (element, frequency count) tuples - and returns the total number of occurrences. - """ - - def combine (a, b): - return 0, a[1] + b[1] - - return reduce(combine_freq, items)[1] - -You might disagree that this style is better. +I really like these rules, but you're free todisagree that this style +is better. The itertools module ----------------------- The ``itertools`` module contains a number of commonly-used iterators -as well as functions for combining iterators. This section will -introduce the module's contents using small examples. +as well as functions for combining several iterators. This section +will introduce the module's contents by showing small examples. ``itertools.count(n)`` returns an infinite stream of integers, increasing by 1 each time. You can optionally supply the @@ -861,7 +895,7 @@ ``itertools.cycle(iter)`` saves a copy of the contents of a provided iterable and returns a new iterator that returns its elements from -first to last, and then repeats these elements infinitely. +first to last. The new iterator will repeat these elements infinitely. :: @@ -878,10 +912,10 @@ itertools.repeat('abc', 5) => abc, abc, abc, abc, abc -``itertools.chain(iterA, iterB, ...)`` takes an arbitrary number of -iterables as input, and returns all the elements of the first iterator, -then all the elements of the second, until all of the iterables -have been exhausted. +``itertools.chain(iterA, iterB, ...)`` takes an arbitrary number of +iterables as input, and returns all the elements of the first +iterator, then all the elements of the second, and so on, until all of +the iterables have been exhausted. :: @@ -895,25 +929,25 @@ ('a', 1), ('b', 2), ('c', 3) This iterator is intended to be used with iterables that are all of -the same length. If the iterables are of different lengths, -the resulting stream will be the same length as the shortest iterable. -Unfortunately, if you passed in any iterators as arguments, -an element may have been taken from the longer iterators -and discarded, meaning that you can't keep using them; if you do, -you risk skipping a discarded element. +the same length. If the iterables are of different lengths, the +resulting stream will be the same length as the shortest iterable. :: itertools.izip(['a', 'b'], (1, 2, 3)) => ('a', 1), ('b', 2) +You should avoid doing this, though, because an element may be taken +from the longer iterators and discarded. This means you can't go on +to use the iterators further because you risk skipping a discarded +element. ``itertools.islice(iter, [start], stop, [step])`` returns a stream that's a slice of the iterator. It can return the first ``stop`` elements. If you supply a starting index, you'll get ``stop-start`` elements, and if you supply a value for ``step` elements will be -skipped. Unlike Python's string and list slicing, you can't use -negative values for ``start``, ``stop``, or ``step``. +skipped accordingly. Unlike Python's string and list slicing, you +can't use negative values for ``start``, ``stop``, or ``step``. :: @@ -943,7 +977,7 @@ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ... -Two functions are for calling other functions on the contents of an +Two functions are used for calling other functions on the contents of an iterable. ``itertools.imap(f, iterA, iterB, ...)`` returns @@ -953,13 +987,13 @@ itertools.imap(operator.add, [5, 6, 5], [1, 2, 3]) => 6, 8, 8 -(The ``operator`` module contains a set of functions +The ``operator`` module contains a set of functions corresponding to Python's operators. Some examples are ``operator.add(a, b)`` (adds two values), ``operator.ne(a, b)`` (same as ``a!=b``), and ``operator.attrgetter('id')`` (returns a callable that -fetches the ``"id"`` attribute), +fetches the ``"id"`` attribute). ``itertools.starmap(func, iter)`` assumes that the iterable will return a stream of tuples, and calls ``f()`` using these tuples as the @@ -1017,10 +1051,11 @@ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ... -The last function, ``itertools.groupby(iter, key_func=None)``, is the -most complicated. ``key_func(elem)`` is a function that can compute a -key value for each element returned by the iterable. If you don't -supply a key function, the key is simply each element itself. +The last function I'll discuss, ``itertools.groupby(iter, +key_func=None)``, is the most complicated. ``key_func(elem)`` is a +function that can compute a key value for each element returned by the +iterable. If you don't supply a key function, the key is simply each +element itself. ``groupby()`` collects all the consecutive elements from the underlying iterable that have the same key value, and returns a stream @@ -1068,7 +1103,7 @@ For programs written in a functional style, you'll sometimes want to construct variants of existing functions that have some of the parameters filled in. Consider a Python function ``f(a, b, c)``; you -could create a new function ``g(b, c)`` that was equivalent to +may wish to create a new function ``g(b, c)`` that was equivalent to ``f(1, b, c)``. This is called "partial function application". The constructor for ``partial`` takes the arguments ``(function, arg1, @@ -1089,15 +1124,6 @@ server_log('Unable to open socket') -Topics to place ------------------------------ - -XXX os.walk() - -XXX Need a large example. - -======= - Acknowledgements ------------------------------ @@ -1108,6 +1134,19 @@ .. comment + Topics to place + ----------------------------- + + XXX os.walk() + + XXX Need a large example. + + But will an example add much? I'll post a first draft and see + what the comments say. + +.. comment + + Original outline: Introduction Idea of FP Programs built out of functions @@ -1141,6 +1180,9 @@ .. comment + Handy little function for printing part of an iterator -- used + while writing this document. + import itertools def print_iter(it): slice = itertools.islice(it, 10) @@ -1153,9 +1195,30 @@ References -------------------- -SICP +General +''''''''''''''' + +**Structure and Interpretation of Computer Programs**, by +Harold Abelson and Gerald Jay Sussman with Julie Sussman. + +Full text at http://mitpress.mit.edu/sicp/. + +A classic textbook of computer science. Chapters 2 and 3 discuss the +use of sequences and streams to organize the data flow inside a +program. The book uses Scheme for its examples, but many of the +design approaches described in these chapters are applicable to +functional-style Python code. + +http://en.wikipedia.org/wiki/Functional_programming: +General Wikipedia entry describing functional programming. + + +Python documentation +''''''''''''''''''''''''''' -Relevant manual sections +http://docs.python.org/lib/module-itertools.html: +Documentation ``for the itertools`` module. -XXX +http://docs.python.org/lib/module-operator.html: +Documentation ``for the operator`` module.

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r47182 - sandbox/trunk/pdb/mconnection.py sandbox/trunk/pdb/mpdb.py
by matt.fleming 30 Jun '06

30 Jun '06

Author: matt.fleming Date: Fri Jun 30 22:12:21 2006 New Revision: 47182 Modified: sandbox/trunk/pdb/mconnection.py sandbox/trunk/pdb/mpdb.py Log: Allow mpdb to use pydb's restart command, both locally and remotely. Modified: sandbox/trunk/pdb/mconnection.py ============================================================================== --- sandbox/trunk/pdb/mconnection.py (original) +++ sandbox/trunk/pdb/mconnection.py Fri Jun 30 22:12:21 2006 @@ -126,7 +126,7 @@ def disconnect(self): if self.output is None or self._sock is None: return - self.output.close() + self.output.shutdown(socket.SHUT_RDWR) self._sock.close() self._sock = None self.listening = False Modified: sandbox/trunk/pdb/mpdb.py ============================================================================== --- sandbox/trunk/pdb/mpdb.py (original) +++ sandbox/trunk/pdb/mpdb.py Fri Jun 30 22:12:21 2006 @@ -111,7 +111,8 @@ ret = self.connection.readline() if ret == '': self.errmsg('Connection closed unexpectedly') - raise Exit + self.onecmd = lambda x: pydb.Pdb.onecmd(self, x) + self.do_rquit(None) # The output from the command that we've just sent to the server # is returned along with the prompt of that server. So we keep reading # until we find our prompt. @@ -121,14 +122,34 @@ # We're probably _never_ going to get that data and that # connection is probably dead. self.errmsg('Connection died unexpectedly') - raise Exit + self.onecmd = lambda x: pydb.Pdb.onecmd(self, x) + self.do_rquit(None) else: ret += self.connection.readline() i += 1 + + # Some 'special' actions must be taken depending on the data returned + if 'restart_now' in ret: + self.connection.write('ACK:restart_now') + self.errmsg('Pdbserver restarting..') + # We've acknowledged a restart, which means that a new pdbserver + # process is started, so we have to connect all over again. + self._disconnect() + time.sleep(3.0) + self.do_target(self.target_addr) + return self.msg_nocr(ret) self.lastcmd = line return + def _disconnect(self): + """ Disconnect a connection. """ + self.connection.disconnect() + self.connection = None + self.target = 'local' + if hasattr(self, 'local_prompt'): + self.prompt = self.local_prompt + def msg_nocr(self, msg, out=None): """Common routine for reporting messages. Derived classes may want to override this to capture output. @@ -248,7 +269,7 @@ return if self.target == 'remote': self.errmsg('Already connected to a remote machine.') - return + return if target == 'tcp': # TODO: need to save state of current debug session if self.connection: self.connection.disconnect() @@ -301,6 +322,7 @@ # in remote_onecmd, because it may be different to this client's. self.local_prompt = self.prompt self.prompt = "" + self.target_addr = target + " " + addr line = self.connection.readline() if line == '': self.errmsg('Connection closed unexpectedly') @@ -382,6 +404,7 @@ except ConnectionFailed, err: self.errmsg("Failed to connect to %s: (%s)" % (comm, err)) return + self.pdbserver_addr = comm self.target = 'remote' self._rebind_input(self.connection) self._rebind_output(self.connection) @@ -395,15 +418,33 @@ return self._rebind_output(self.orig_stdout) self._rebind_input(self.orig_stdin) - if self.connection != None: - self.connection.disconnect() - if hasattr(self, 'local_prompt'): - self.prompt = self.local_prompt - self.msg('Exiting remote debugging...') + self._disconnect() self.target = 'local' self.do_quit(None) raise Exit + def do_restart(self, arg): + """ Extend pydb.do_restart to signal to any clients connected on + a debugger's connection that this debugger is going to be restarted. + All state is lost, and a new copy of the debugger is used. + """ + # We don't proceed with the restart until the action has been + # ACK'd by any connected clients + if self.connection != None: + self.msg('restart_now\n(MPdb)') + line = "" + while not 'ACK:restart_now' in line: + line = self.connection.readline() + try: + self.do_rquit(None) + except Exit: + pass + else: + self.msg("Re exec'ing\n\t%s" % self._sys_argv) + os.execvp(self._sys_argv[0], self._sys_argv) + + + def do_thread(self, arg): """Use this command to switch between threads. The new thread ID must be currently known.

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r47181 - python/trunk/Doc/lib/libfuncs.tex
by fred.drake 30 Jun '06

30 Jun '06

Author: fred.drake Date: Fri Jun 30 21:29:25 2006 New Revision: 47181 Modified: python/trunk/Doc/lib/libfuncs.tex Log: - consistency nit: always include "()" in \function and \method (*should* be done by the presentation, but that requires changes all over) - avoid spreading the __name meme Modified: python/trunk/Doc/lib/libfuncs.tex ============================================================================== --- python/trunk/Doc/lib/libfuncs.tex (original) +++ python/trunk/Doc/lib/libfuncs.tex Fri Jun 30 21:29:25 2006 @@ -781,30 +781,30 @@ \begin{verbatim} class C(object): def __init__(self): self.__x = None - def getx(self): return self.__x - def setx(self, value): self.__x = value - def delx(self): del self.__x + def getx(self): return self._x + def setx(self, value): self._x = value + def delx(self): del self._x x = property(getx, setx, delx, "I'm the 'x' property.") \end{verbatim} If given, \var{doc} will be the docstring of the property attribute. Otherwise, the property will copy \var{fget}'s docstring (if it exists). This makes it possible to create read-only properties - easily using \function{property} as a decorator: + easily using \function{property()} as a decorator: \begin{verbatim} class Parrot(object): def __init__(self): - self.__voltage = 100000 + self._voltage = 100000 @property def voltage(self): """Get the current voltage.""" - return self.__voltage + return self._voltage \end{verbatim} - turns the \method{voltage} method into a "getter" for a read-only attribute - with the same name. + turns the \method{voltage()} method into a ``getter'' for a read-only + attribute with the same name. \versionadded{2.2} \versionchanged[Use \var{fget}'s docstring if no \var{doc} given]{2.5}

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buildbot failure in PPC64 Debian trunk
by buildbot＠python.org 30 Jun '06

30 Jun '06

The Buildbot has detected a new failure of PPC64 Debian trunk. Full details are available at: http://www.python.org/dev/buildbot/all/PPC64%2520Debian%2520trunk/builds/260 Buildbot URL: http://www.python.org/dev/buildbot/all/ Build Reason: Build Source Stamp: [branch trunk] HEAD Blamelist: tim.peters BUILD FAILED: failed failed slave lost sincerely, -The Buildbot

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