What's new in this release?
---------------------------
There's a loooong list of changes since release 1.4 in the file
Misc/NEWS. Some highlights:
- It's much faster (almost twice for the Lib/test/pystone.py benchmark.)
- There is now an assert statement: ``assert <condition>'' or ``assert <condition>, <errormessage>''. It raises AssertionError if the condition evaluates to false. The default error message is empty; the source text of the assertion statement is printed as part of the traceback.
- There is now built-in support for importing hierarchical module names (e.g. "import spam.ham.eggs"); ni is declared obsolete. Note that the built-in package support is somewhat simpler (no __ and __domain__) and differs in one crucial aspect: __init__.py is required, and loaded in the package's namespace instead of as a submodule. For more information, see
http://grail.cnri.reston.va.us/python/e ... kages.html.
- The new "re" module (Perl style regular expressions) is here. It is based on Philip Hazel's pcre code; the Python interfaces were put together by Andrew Kuchling, Tim Peters and Jeffrey Ollie. The regex module is declared obsolete.
- In support of the re module, a new form of string literals is introduced, "raw strings": e.g. r"\n" is equal to "\\n".
- All standard exceptions and most exceptions defined in standard extension modules are now classes. Use python -X to revert back to string exceptions. See
http://grail.cnri.reston.va.us/python/e ... tions.html for more info.
- Comparisons can now raise exceptions (previously, exceptions occuring during comparisons were swept under the rug).
- New dictionary methods: .clear(), .copy(), .update(), .get(). The first two are obvious; d1.update(d2) is equivalent to the for loop ``for k in d2.keys(): d1[k] = d2[k]''; and d.get(k) returns d[k] if it exists and None (or the optional second argument) if not.
- There is a new regression test harness, which tests many more modules. (To run the tests, do "import test.autotest".)
- The interpreter is much smarter about the initial value for sys.path; you can control it easier using $PYTHONHOME (see the usage
message, e.g. try ``python -h''). In most situations, the interpreter can be installed at an arbitrary location without having to recompile.
- The build process now builds a single library (libpython1.5.a) which contains everything except for the main() entry point. This makes life much easier for applications that embed Python.
- There is much better support for embedding, including threads, multiple interpreters(!), uninitialization, and access to the global interpreter lock.
- There is a -O option that removes SET_LINENO instructions, assert statements and code prefixed with ``if __debug__: ...''. (It still
only makes a few percent difference, so don't get all worked up about this.)
- The Grand Renaming is completed: all linker-visible symbols defined by Python now have a "Py" or "_Py" prefix, and the same is
true for most macros and typedefs.
