01 May 2021

Nuitka Release 0.6.14

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

This release has few, but important bug fixes. The main focus was on expanding standalone support, esp. for PySide2, but also and in general with plugins added that workaround pkg_resources usage for version information.

Also an important new features was added, e.g. the project configuration in the main file should prove to be very useful.

Bug Fixes

  • Compatibility: Fix, modules that failed to import, should be retried on next import.

    So far we only ever executed the module body once, but that is not how it’s supposed to be. Instead, only if it’s in sys.modules that should happen, which is the case after successful import.

  • Compatibility: Fix, constant False values in right hand side of and/or conditions were generating wrong code if the left side was of known bool shape too.

  • Standalone: Fix, add styles Qt plugins to list of sensible plugins.

    Otherwise no mouse hover events are generated on some platforms.

  • Compatibility: Fix, relative from imports beyond level 1 were not loadingg modules from packages if necessary. Fixed in already.

  • Standalone: The crypto DLL check for Qt bindings was wrong. Fixed in already.

  • Standalone: Added experimental support for PySide6, but for good results, 6.1 will be needed.

  • Standalone: Added support for newer matplotlib. Fixed in already.

  • Standalone: Reverted changes related to pkg_resources that were causing regressions. Fixed in already.

  • Standalone: Adding missing implicit dependency for cytoolz package. Fixed in already.

  • Standalone: Matching for package names to not suggest recompile for was broken and didn’t match. Fixed in already.

New Features

  • Added support for project options.

    When found in the filename provided, Nuitka will inject options to the commandline, such that it becomes possible to do a complex project with only using

    python -m nuitka filename.py
    # Compilation mode, support OS specific.
    # nuitka-project-if: {OS} in ("Windows", "Linux"):
    #    nuitka-project: --onefile
    # nuitka-project-if: {OS} not in ("Windows", "Linux"):
    #    nuitka-project: --standalone
    # The PySide2 plugin covers qt-plugins
    # nuitka-project: --enable-plugin=pyside2
    # nuitka-project: --include-qt-plugins=sensible,qml
    # The pkg-resources plugin is not yet automatic
    # nuitka-project: --enable-plugin=pkg-resources
    # Nuitka Commercial only features follow:
    # Protect the constants from being readable.
    # nuitka-project: --enable-plugin=data-hiding
    # Include datafiles for Qt into the binary directory.
    # nuitka-project: --enable-plugin=datafile-inclusion
    # nuitka-project: --qt-datadir={MAIN_DIRECTORY}
    # nuitka-project: --qt-datafile-pattern=*.js
    # nuitka-project: --qt-datafile-pattern=*.qml
    # nuitka-project: --qt-datafile-pattern=*.svg
    # nuitka-project: --qt-datafile-pattern=*.png

    Refer to the User Manual for a table of directives and the variables allowed to be used.

  • Added option to include whole data directory structures in standalone.

    The new option --include-data-dir was added and is mostly required for onefile mode, but recommended for standalone too.

  • Added pkg-resources plugin.

    This one can resolve code like this at compile time without any need for pip metadata to be present or used.

  • Standalone: Also process early imports in optimization.

    Otherwise plugins cannot work on standard library modules. This makes it possible to handle them as well.


  • Faster binary operations.

    Applying lessons learnt during the enhancements for in-place operations that initially gave worse results than some manual code, we apply the same tricks for all binary operations, which speeds them up by significant margins, e.g. 30% for float addition, 25% for Python int addition, and still 6% for Python int addition.

  • More direct optimization of unary operations on constant value.

    Without this, -1 was not directly a constant value, but had to go through the unary - operation, which it still does, but now it’s done at tree building time.

  • More direct optimization for not in branches.

    Invertible comparisons, i.e. is/is not and in/not in do not have do be done during optimization. This mainly avoids noise during optimization from such unimportant steps.

  • More direct optimization for constant slices.

    These are used in Python3 for all subscripts, e.g. a[1:2] will use slice(1,2) effectively. For Python2 they are used less often, but still. This also avoids a lot of noise during optimization, mostly on Python3

  • Scons: Avoid writing database to disk entirely.

    This saves a bit of disk churn and makes it unnecessary to specify the location such that it doesn’t collide between Python versions.

  • For optimization passes, use previous max total as minimum for next pass. That will usually be a more accurate result, rather than starting from 1 again. Part of already.

  • Enhancements to the branch merging improve the scalability of Nuitka somewhat, although the merging itself is still not very scalable, there are some modules that are very slow to optimize still.

  • Use orderset if available over the inline copy for OrderedSet which is much faster and improves Nuitka compile times.

  • Make pkgutil a hard import too, this is in preparation of more optimization for its functions.


  • Upstream patches for PySide6 have been contributed and merged into the development branch dev. Full support should be available once this is released as part of 6.1 which is waiting for Qt 6.1 naturally.

  • Patches for PySide2 are available to commercial customers, see PySide2 support page.

  • Formatted all documents with rstfmt and made that part of the commit hook for Nuitka. It now works for all documents we have.

  • Updated inline copy of tqdm to 4.59.0 which ought to address spurious errors given.

  • User Manual: Remove --show-progress from the tutoral. The default progress bar is then disabled, and is actually much nicer to use.

  • Developer Manual: Added description of how context managers should be named.

  • Cleanup language for some warnings and outputs.

    It was still using obsolete “recursion” language rather than talking about “following imports”, which is the new one.


  • Remove dead code related to constants marshal, the data composer has replaced this.

  • Avoid internal API usage for loading extension modules on Linux, there is a function in sys module to get the ld flags.


  • Fix, the only mode wasn’t working properly.

  • Use new project options feature for specific options in basic tests allowing to remove them from the test runner.


For PySide2 things became more perfect, but it takes upstream patches unfortunately such that only PySide6.1 will be working out of the box outside of the commercial offering. We will also attempt to provide workarounds, but there are some things that cannot be done that way.

This release added some more scalability to the optimization process, however there will be more work needed to make efficient branch merges.

For onefile, a feature to include whole directories had been missing, and could not easily be achieved with the existing options. This further rounds this up, now what’s considered missing is compression and macOS support, both of which should be coming in a future release.

For the performance side of things, the binary operator work can actually yield pretty good gains, with double digit improvements, but this covers only so much. Much more C types and better type tracing would be needed, but there was no progress on this front. Future releases will have to revisit the type tracing to make sure, we know more about loop variables, etc. so we can achieve the near C speed we are looking for, at least in the field of int performance.

This release has largely been driven by the Nuitka Commercial offering and needs for compatibility with more code, which is of course always a good thing.