Nuitka Release 0.5.17

This is to inform you about the new stable release of Nuitka. It is the extremely compatible Python compiler. Please see the page "What is Nuitka?" for an overview.

This release is a major feature release, as it adds full support for Python3.5 and its coroutines. In addition, in order to properly support coroutines, the generator implementation got enhanced. On top of that, there is the usual range of corrections.

Bug Fixes

  • Windows: Command line arguments that are unicode strings were not properly working.
  • Compatibility: Fix, only the code object attached to exceptions contained all variable names, but not the one of the function object.
  • Python3: Support for virtualenv on Windows was using non-portable code and therefore failing. Issue#266.
  • The tree displayed with --display-tree duplicated all functions and did not resolve source lines for functions. It also displayed unused functions, which is not helpful.
  • Generators with parameters leaked C level memory for each instance of them leading to memory bloat for long running programs that use a lot of generators. Fixed in already.
  • Don't drop positional arguments when called with --run, also make it an error if they are present without that option.

New Features

  • Added full support for Python3.5, coroutines work now too.


  • Optimized frame access of generators to not use both a local frame variable and the frame object stored in the generator object itself. This gave about 1% speed up to setting them up.
  • Avoid having multiple code objects for functions that can raise and have local variables. Previously one code object would be used to create the function (with parameter variable names only) and when raising an exception, another one would be used (with all local variable names). Creating them both at start-up was wasteful and also needed two tuples to be created, thus more constants setup code.
  • The entry point for generators is now shared code instead of being generated for each one over and over. This should make things more cache local and also results in less generated C code.
  • When creating frame codes, avoid working with strings, but use proper emission for less memory churn during code generation.


  • Updated the key for the Debian/Ubuntu repositories to remain valid for 2 more years.
  • Added support for Fedora 23.
  • MinGW32 is no more supported, use MinGW64 in the 32 bits variant, which has less issues.


  • Detecting function type ahead of times, allows to handle generators different from normal functions immediately.
  • Massive removal of code duplication between normal functions and generator functions. The later are now normal functions creating generator objects, which makes them much more lightweight.
  • The return statement in generators is now immediately set to the proper node as opposed to doing this in variable closure phase only. We can now use the ahead knowledge of the function type.
  • The nonlocal statement is now immediately checked for syntax errors as opposed to doing that only in variable closure phase.
  • The name of contraction making functions is no longer skewed to empty, but the real thing instead. The code name is solved differently now.
  • The local_locals mode for function node was removed, it was always true ever since Python2 list contractions stop using pseudo functions.
  • The outline nodes allowed to provide a body when creating them, although creating that body required using the outline node already to create temporary variables. Removed that argument.
  • Removed PyLint false positive annotations no more needed for PyLint 1.5 and solved some TODOs.
  • Code objects are now mostly created from specs (not yet complete) which are attached and shared between statement frames and function creations nodes, in order to have less guess work to do.


  • Added the CPython3.5 test suite.
  • Updated generated doctests to fix typos and use common code in all CPython test suites.


This release continues to address technical debt. Adding support for Python3.5 was the major driving force, while at the same time removing obstacles to the changes that were needed for coroutine support.

With Python3.5 sorted out, it will be time to focus on general optimization again, but there is more technical debt related to classes, so the cleanup has to continue.


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