Nuitka Release 0.5.20

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 mostly about catching up with issues. Most address standalone problems with special modules, but there are also some general compatibility corrections, as well as important fixes for Python3.5 and coroutines and to improve compatibility with special Python variants like AnaConda under the Windows system.

Bug Fixes

  • Standalone Python3.5: The _decimal module at least is using a __name__ that doesn't match the name at load time, causing programs that use it to crash.
  • Compatibility: For Python3.3 the __loader__ attribute is now set in all cases, and it needs to have a __module__ attribute. This makes inspection as done by e.g. flask working.
  • Standalone: Added missing hidden dependencies for Tkinter module, adding support for this to work properly.
  • Windows: Detecting the Python DLL and EXE used at compile time and preserving this information use during backend compilation. This should make sure we use the proper ones, and avoids hacks for specific Python variants, enhancing the support for AnaConda, WinPython, and CPython installations.
  • Windows: The --python-debug flag now properly detects if the run time is supporting things and error exits if it's not available. For a CPython3.5 installation, it will switch between debug and non-debug Python binaries and DLLs.
  • Standalone: Added plug-in for the Pwm package to properly combine it into a single file, suitable for distribution.
  • Standalone: Packages from standard library, e.g. xml now have proper __path__ as a list and not as a string value, which breaks code of e.g. PyXML. Issue#183.
  • Standalone: Added missing dependency of twisted.protocols.tls. Issue#288.
  • Python3.5: When finalizing coroutines that were not finished, a corruption of its reference count could happen under some circumstances.
  • Standalone: Added missing DLL dependency of the uuid module at run time, which uses ctypes to load it.

New Features

  • Added support for AnaConda Python on this Linux. Both accelerated and standalone mode work now. Issue#295.
  • Added support for standalone mode on FreeBSD. Issue#294.
  • The plug-in framework was expanded with new features to allow addressing some specific issues.


  • Moved memory related stuff to dedicated utils package nuitka.utils.MemoryUsage as part of an effort to have more topical modules.
  • Plug-ins how have a dedicated module through which the core accesses the API, which was partially cleaned up.
  • No more "early" and "late" import detections for standalone mode. We now scan everything at the start.


This release focused on expanding plugins. These were then used to enhance the success of standalone compatibility. Eventually this should lead to a finished and documented plug-in API, which will open up the Nuitka core to easier hacks and more user contribution for these topics.

Nuitka Release 0.5.19

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 brings optimization improvements for dictionary using code. This is now lowering subscripts to dictionary accesses where possible and adds new code generation for known dictionary values. Besides this there is the usual range of bug fixes.

Bug Fixes

  • Fix, attribute assignments or deletions where the assigned value or the attribute source was statically raising crashed the compiler.
  • Fix, the order of evaluation during optimization was considered in the wrong order for attribute assignments source and value.
  • Windows: Fix, when g++ is the path, it was not used automatically, but now it is.
  • Windows: Detect the 32 bits variant of MinGW64 too.
  • Python3.4: The finalize of compiled generators could corrupt reference counts for shared generator objects. Fixed in already.
  • Python3.5: The finalize of compiled coroutines could corrupt reference counts for shared generator objects.


  • When a variable is known to have dictionary shape (assigned from a constant value, result of dict built-in, or a general dictionary creation), or the branch merge thereof, we lower subscripts from expecting mapping nodes to dictionary specific nodes. These generate more efficient code, and some are then known to not raise an exception.

    def someFunction(a,b):
        value = {a : b}
        value["c"] = 1
        return value

    The above function is not yet fully optimized (dictionary key/value tracing is not yet finished), however it at least knows that no exception can raise from assigning value["c"] anymore and creates more efficient code for the typical result = {} functions.

  • The use of "logical" sharing during optimization has been replaced with checks for actual sharing. So closure variables that were written to in dead code no longer inhibit optimization of the then no more shared local variable.

  • Global variable traces are now faster to decide definite writes without need to check traces for this each time.


  • No more using "logical sharing" allowed to remove that function entirely.
  • Using "technical sharing" less often for decisions during optimization and instead rely more often on proper variable registry.
  • Connected variables with their global variable trace statically avoid the need to check in variable registry for it.
  • Removed old and mostly unused "assume unclear locals" indications, we use global variable traces for this now.


This release aimed at dictionary tracing. As a first step, the value assign is now traced to have a dictionary shape, and this this then used to lower the operations which used to be normal subscript operations to mapping, but now can be more specific.

Making use of the dictionary values knowledge, tracing keys and values is not yet inside the scope, but expected to follow. We got the first signs of type inference here, but to really take advantage, more specific shape tracing will be needed.