11 September 2010

Nuitka Release 0.2.2

This is to inform you about the new stable release of Nuitka. It is the extremely compatible Python compiler, “download now”.

This is some significant progress, a lot of important things were addressed.

Bug Fixes

  • Scope analysis is now done during the tree building instead of sometimes during code generation, this fixed a few issues that didn’t show up in tests previously.

  • Reference leaks of generator expressions that were not fishing, but then deleted are not more.

  • Inlining of exec is more correct now.

  • More accurate exception lines when iterator creation executes compiled code, e.g. in a for loop

  • The list of base classes of a class was evaluated in the context of the class, now it is done in the context of the containing scope.

  • The first iterated of a generator expression was evaluated in its own context, now it is done in the context of the containing scope.

Reduced Differences

  • With the enhanced scope analysis, UnboundLocalError is now correctly supported.

  • Generator expressions (but not yet functions) have a throw(), send() and close() method.

  • Exec can now write to local function namespace even if None is provided at run time.

  • Relative imports inside packages are now correctly resolved at compile time when using --deep.

Cleanups

  • The compiled function type got further enhanced and cleaned up.

  • The compiled generator expression function type lead to a massive cleanup of the code for generator expressions.

  • Cleaned up namespaces, was still using old names, or “Py*” which is reserved to core CPython.

  • Overhaul of the code responsible for eval and exec, it has been split, and it pushed the detection defaults to the C++ compiler which means, we can do it at run time or compile time, depending on circumstances.

  • Made PyTemporaryObject safer to use, disabling copy constructor it should be also a relief to the C++ compiler if it doesn’t have to eliminate all its uses.

  • The way delayed work is handled in TreeBuilding step has been changed to use closured functions, should be more readable.

  • Some more code templates have been created, making the code generation more readable in some parts. More to come.

New Features

  • As I start to consider announcing Nuitka, I moved the version logic so that the version can now be queried with --version.

Optimization

  • Name lookups for None, True and False and now always detected as constants, eliminating many useless module variable lookups.

New Tests

  • More complete test of generator expressions.

  • Added test program for packages with relative imports inside the package.

  • The built-in dir() in a function was not having fully deterministic output list, now it does.

Summary

Overall, the amount of differences between CPython and Nuitka is heading towards zero. Also most of the improvements done in this release were very straightforward cleanups and not much work was required, mostly things are about cleanups and then it becomes easily right. The new type for the compiled generator expressions was simple to create, esp. as I could check what CPython does in its source code.

For optimization purposes, I decided that generator expressions and generator functions will be separate compiled types, as most of their behavior will not be shared. I believe optimizing generator expressions to run well is an important enough goal to warrant that they have their own implementation. Now that this is done, I will repeat it with generator functions.

Generator functions already work quite fine, but like generator expressions did before this release, they can leak references if not finished , and they don’t have the throw() method, which seems very important to the correct operation of contextlib. So I will introduce a decicated type for these too, possibly in the next release.

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