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'zugbruecke' 0.2 released
Calling into Windows DLLs under Linux, MacOS or BSD

Significantly improved 0.2 release of zugbruecke, a ctypes drop-in replacement for calling Windows DLLs from Unix-like systems and pleiszenburg.de open source project.

  • Interoperability
  • Linux
  • Python
  • Python Module
  • Software Development
  • Unix
  • Wine
  • ctypes


zugbruecke is an experimental Python package (currently in development status 3/alpha). It allows to call routines in Windows DLLs from Python code running on Unices / Unix-like systems such as Linux, MacOS or BSD. zugbruecke is designed as a drop-in replacement for Python's standard library's ctypes module. zugbruecke is built on top of Wine. A stand-alone Windows Python interpreter launched in the background is used to execute the called DLL routines. Communication between the Unix-side and the Windows/Wine-side is based on Python's build-in multiprocessing connection capability. zugbruecke has (limited) support for pointers, struct types and call-back functions. zugbruecke comes with extensive logging features allowing to debug problems associated with both itself and with Wine. zugbruecke is written using Python 3 syntax and primarily targets the CPython implementation of Python.

After its initial release in 2017, this is the third generation of zugbruecke, working towards more stability, speed and compatibility with ctypes. Next to many other bug fixes and improvements, version 0.2 primarily lays the groundwork for memory symmetry, a long standing and complicated to solve issue. An initial implementation is expected to be part of version 0.3.


CAUTION: A number changes at least partially BREAK BACKWARDS COMPATIBILITY for certain use and edge cases.

The datatype parser and definition code was rewritten completely. It should work as before in almost all instances although unexpected breakages may occur.

If entire struct objects are synced via memsync directives, the struct types now have to be specified directly instead of their names as strings as before, breaking backwards compatibility for those use cases.

zugbruecke now follows the Python's logging module's log levels. Maximum logging output can now be achieved via logging.DEBUG or 10 as opposed to 100 in earlier versions. Log level 0 remains as "no logs" as per logging.NOTSET. This change may break debugging and development workflows.

This RELEASE FIXES A CRITICAL BUG where zugbruecke was falsely translating 64 bit integer types from the Unix side to 32 bit integer types on the Wine side.

  • FEATURE: Improved performance. With logging disabled, function calls carry 10% less overhead on average.
  • FEATURE: In memsync directives, ctypes types do not need to be specified by their name as strings anymore - plain ctypes fundamental types and structure types can be used instead. Strings remain valid specifications (only) for fundamental ctypes types for compatibility though.
  • FEATURE: memsync directives allow for more descriptive parameter names while the old single-character names remain valid for compatibility.
  • FEATURE: Added support for CPython 3.11, see #86 and #87.
  • FEATURE: Logging now relies on Python's logging module's log levels, i.e. NOTSET, DEBUG, INFO, WARNING, ERROR and CRITICAL. This change serves to work towards #84.
  • FEATURE: Log output has been divided into log levels, see #9.
  • FEATURE: Added support for fixed-length arrays of function pointers (for callback functions). Similar to individual function pointers in zugbruecke, the pointers can not be overwritten by DLL functions.
  • FIX: Argtypes and restype would translate c_int64, c_uint64, c_long and c_ulong from the Unix side to their 32-bit equivalents, c_int32 and c_uint32, on the Wine side. This was due to c_long and c_ulong being 8 bytes long on Unix-like systems while they are 4 bytes long on Window, see #95.
  • FIX: Fixed-length c_char and c_wchar buffers passed by value within structures were not handled correctly, see #93.
  • FIX: The new argtypes and restype parser does not suffer from #61 anymore where earlier different structure types from different name spaces but with identical names would cause problems.
  • FIX: CI revealed that an issue similar to #50 returned as packages on Wine side can sometimes not be imported if they are symlinked. The new copy_modules configuration parameter can be used to indicate that a copy instead of symlinks is required. This problem is caused by Wine bug #54228 in Wine Staging >= 7.18, see #94.
  • FIX: If zugbruecke (and wenv) were installed into user site-packages, the installation would break, see #88.
  • FIX: If writing of logs to disk (log_write) was set to True during run-time, zugbruecke would crash, see #77.
  • FIX: Syncing entire structs via memsync was broken, see #92.
  • FIX: restype was explicitly assumed to be c_int. Now, if a user does not specify it, assumptions about it are left to ctypes on the Wine side, potentially getting closer to ctypes original behaviour.
  • FIX: restype would not throw an exception when by accident set to a list or tuple like original ctypes does.
  • FIX: By value simple type members of structs passed as pointer / by reference were not synchronized correctly. This includes scalar integers and floats, individual c_char and c_wchar objects as well as c_char and c_wchar arrays, i.e. strings.
  • FIX: The type parser's cache could, under certain circumstances, confuse fixed-length struct array types with their scalar base types.
  • FIX: Indicate Python 3.11 support in pyproject.toml.
  • DEPRECATED: Single-character parameter names in memsync directives.
  • DEPRECATED: ctypes fundamental types specified by name as strings in memsync directives.
  • DOCS: More detailed explanation of memsync, where it is needed and where it is not, among other improvements.
  • DOCS: Added explanation of handling of long integer types.
  • DOCS: Added explanation of handling of floating point types and the lack of "long double" as well as "half precision" support.
  • DOCS: Updated benchmarks.
  • DOCS: Removed old examples folder from project as its code was more than outdated and can now be found in the documentation, the test suite and/or the newly added benchmarks.
  • DOCS: Updated benchmarks.
  • DOCS: Added notes on known CentOS issues.
  • DOCS: Added information on known symbolic link issues with certain versions of Wine, recently staging >=7.18, see #94.
  • DOCS: Many small fixes.
  • DEV: Added tests on custom types and array.array objects (standard library) as well as numpy.ndarray objects.
  • DEV: Added tests for 64 bit integer limits / overflows for win64.
  • DEV: Added tests on restype configuration errors.
  • DEV: Cleaned and clarified all tests. Renamed all tests to more meaningful names referring to the features that they are testing.
  • DEV: Test support library cleaned up, documented and typed.
  • DEV: New benchmark infrastructure similar to the test suite, allowing to easily add benchmarks. Their results now get automatically included into the project documentation.
  • DEV: Added test for light-weight pointers, ctypes.byref. Those were previously supported but remained untested.


Installation instructions are part of the project's comprehensive documentation on Read the Docs.

Further Information

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