Decimal type still chugging along

Facundo Batista updated PEP 327 with what are close to the last issues for the PEP. There has also been some recent activity in the sandbox on the package. It could still make it into 2.4 ...

And it has! As I wrote this Decimal.py graduated kindergarten, left the sandbox, and is now out on the playground with the rest of Lib. Play nice.

Contributing threads:

• PEP 327 (Decimal data type) updated and status

CVS docs, now in handy tarball form

Fred Drake has tweaked the script that puts up new versions of the CVS docs to also upload a tarball of the HTML. You can find that and links to the other in-development documentation at http://www.python.org/dev/doc/ .

Contributing threads:

• Downloadable HTML from the trunk

Proposed additions to heapq API

Raymond Hettinger proposed adding two new functions to the heapq API. heappushpop() would take an item, push it on to the heap, and then pop off the smallest value. heapiter() would return a destructive iterator. The actual implementation of heappushpop() got the most discussion.

No final decision has been made, so if either function sounds good to you then do speak up.

Contributing threads:

• heapq API

Consolidation of CJK codecs

Hye-Shik Chang consolidated the various CJK codecs into various files and managed to save some space in terms of the files themselves. As M-A Lemburg pointed out, though, there was no need to in terms of loading size since most linkers mmap only what is needed to run.

Contributing threads:

• Planned updates for cjkcodecs before 2.4a1

Function decorators in 2.4 ... maybe

The topic of whether function decorators would go into 2.4, and if so with what syntax, continued to be debated from the last summary. Beyond reference implementations (which include an implementation not requiring new syntax), nothing really changed. Overall people agreed they would like to see it in 2.4 using whatever syntax Guido chooses (and he has three in mind, so no more suggestions!), but if he felt the need to wait then functionality would be held off for 2.5 .

Contributing threads:

• functions decorators in 2.4?
• decorators and 2.4

Making ''.join(list_of_strs) an inconsequential idiom

As most people know, concatenating strings in a 'for' loop is a bad idea; the idiom you are supposed to use is to store the strings you want to concatenate in a list and the pass it to ''.join(list_of_strs). This is because string addition requires allocating memory for the size of the concatenation and then copying from both strings into the new memory. The constant new memory allocation is costly when you have a loop that goes for more than a few iterations.

Raymond Hettinger suggested altering the str object to have a pointer that would point to any strings that were meant to be treated as concatenated to the current string. The problem with this is that it grew the str object the size of a pointer and that is costly for a object as common as string.

Armin Rigo gave this challenge a shot and ended up with a bunch of code that special-cases the BINARY_ADD opcode. Neither solution as been accepted at this moment.

Contributing threads:

• Wild Idea for the Year
• Building strings with +=

Possible exposure of universal newlines outside of the file object

Scott David Daniels suggested a new itertools function that would work like universal newlines but for strings or files already opened without universal newlines turned on. People were receptive to the idea, just not for putting it into itertools. Suggestions ranged from exposing the functionality as a static method of the file type to sticking it into 'string'. No conclusion of where to put it was reached.

Contributing threads:

• Possible addition to itertools

NOP does exist I tell you!

Raymond Hettinger asked if anyone objected to adding a no-op opcode (aptly named NOP). People said nope (see? "NOP", "nope", sound the same? <eddie izzard>Forget it</eddie izzard>). So it's in.

Contributing threads:

• NOP

Yes, the Windows binary for 2.4 will use VC 7.1

Yes, Python 2.4 will use VC 7.1 . No, we are not going to have a VC 6 binary (you can build it if you want, though). No, distributing the needed DLLs with the installer does not go against the GPL to the best of our knowledge (even though the codebase is not GPL but more BSD and no one from the FSF has told it including the DLLs is wrong). Maybe, we will use Martin v. Loewis' MSI installer, maybe not (still being debated as this was being written).

Contributing threads:

• VC 7.1 maintenance?

Possible itertools additions

Raymond Hettinger suggested two itertools additions; count_elements and pairswap. The former counts the number of times an item appears in the passed-in iterable and returns pairs of the count and the item. The latter takes an iterable that returns pairs and returns an iterable that returns those pairs swapped.

In the end people didn't see the need for pairswap. People did want count_elements, but not as an iterator but as something that returned a dictionary. It was suggested as both a class method of dict and as a new bucket type that could possibly go into the 'collections' module. No final decisions yet, though.

Contributing threads:

• Candidate Itertools

Gettin' PEP 292 ("Simpler String Substitutions") into 2.4

Barry Warsaw brought up the point that PEP 292 was slated to go into 2.4 (it's currently in the sandbox). The two biggest questions was the names of the new functions and where to stick them. The name issue was not quite as bad once Barry explained the reasoning behind the existing names.

Where to put the code, though, was not so easily dealt with. The original idea (which Barry and I came up with, so I am biased here) was to turn the string module into a package with the new code going there. Barry also pointed out that the code in 'string' that is deprecated and will eventually go away can be moved into an individual module that can just simply be deleted from the package later and then dismissed with the removal of a single import * line in __init__.py for the package.

Not everyone saw the utopia Barry and I were trying to build. People suggested just not bothering with turning 'string' into a package. Still others suggested a new package altogether; 'stringlib' and 'text' were suggested names. It's still not resolved.

Contributing threads:

• PEP 292 for Python 2.4

Having u.encode() return something other than strings

Currently unicode.encode() returns only strings. M-A Lemburg wanted to lift this restriction. Guido pointed out that this could possibly cause problems for type inferencing since the return type would vary based on an argument (which made me happy since my masters thesis ties into this stuff). A compromise was reached where the method will only return 8-bit or Unicode strings; basically only subtypes of basestring.

Contributing threads:

• Allowing u.encode() to return non-strings

Comparing floats and longs is a pain

Basically this all boiled down to this (quoted from Michael Chermside): "when comparing a long with a float where the exponent is larger than the precision, that the float should be treated as if it were EXACTLY EQUAL TO <coefficient>*2^<exponent>, instead of trying to treat it as some sort of a range." Guido said he would like to see this in 2.4 if someone would write up the code and commit it.

Contributing threads:

• Comparing heterogeneous types

German and Turkish docstrings from pydoc

Martin v. Loewis is currently trying to figure out where to put partial translations of docstrings in the stdlib for pydoc to use as appropriate.

Contributing threads:

• Including translated doc strings in 2.4

What to do when 'raise' is called after the last exception was caught

What should happen if you call 'raise' when you already caught the last exception that was raised? People debated what the official docs said. Seemed to coalesce to be what ever the last exception was; caught or not. This ties into being what exception was currently stored.

Contributing threads:

• Re-raise in absence of an "active" exception

Can you help with cleaning up the Demo directory?

The Demo directory is in need of some TLC. A bunch of modules in there are out of date and could use an update to current Python abilities. If you care to help by submitting patches to update the code that would be great. There is a large swath of code in there varying from extremely simple to involved so if the mood ever strikes you there will be something for everyone.

And if you attend the next Python Bug Day you can also work on it then.

Contributing threads:

• What can we do about dealing with the Demo directory?

No more expected test failures on Windows for 2.4

The bsddb tests are now expected to pass on Windows. What this means is that failures are no longer the norm on Windows for the Python regression testing suite.

Contributing threads:

• Joy in Berkeley Windowsland

Getting accessible local dicts per thread

Jim Fulton wanted to expose the pre-thread local dict . He has an implementation going that he is going to play with and work the kinks out of. After that the code will most likely be committed.

Contributing threads:

• Proposal: thread.get_dict

Where to stick SHA-256

Someone contributed a patch for adding SHA-256 support. A discussion built up over where to put it, if at all. It's still going on at this moment. Most people seem to agree that if it is included, it should either just be another function in the sha module or that sha.sha() should accept an optional argument specifying how many bits to use for the hash.

Contributing threads:

• SHA-256 module

Making weakrefs subclassable

Fred Drake has a patch to add the ability to subclass weakrefs. He wasn't sure if there would be a performance penalty though. But Tim Peters stepped up and said there wouldn't be. So it looks like it should go in shortly.

Contributing threads:

• making weakref.ref objects subclassable