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Diffstat (limited to 'docs/faq.rst')
| -rw-r--r-- | docs/faq.rst | 55 |
1 files changed, 10 insertions, 45 deletions
diff --git a/docs/faq.rst b/docs/faq.rst index 8bf05a40..1eb00efa 100644 --- a/docs/faq.rst +++ b/docs/faq.rst @@ -5,12 +5,10 @@ Frequently asked questions =========================================================== 1. Make sure that the name specified in PYBIND11_MODULE is identical to the -filename of the extension library (without suffixes such as .so) +filename of the extension library (without suffixes such as ``.so``). 2. If the above did not fix the issue, you are likely using an incompatible -version of Python (for instance, the extension library was compiled against -Python 2, while the interpreter is running on top of some version of Python -3, or vice versa). +version of Python that does not match what you compiled with. "Symbol not found: ``__Py_ZeroStruct`` / ``_PyInstanceMethod_Type``" ======================================================================== @@ -54,7 +52,7 @@ provided by the caller -- in fact, it does nothing at all. .. code-block:: python def increment(i): - i += 1 # nope.. + i += 1 # nope.. pybind11 is also affected by such language-level conventions, which means that binding ``increment`` or ``increment_ptr`` will also create Python functions @@ -147,7 +145,7 @@ using C++14 template metaprogramming. .. _`faq:hidden_visibility`: -"‘SomeClass’ declared with greater visibility than the type of its field ‘SomeClass::member’ [-Wattributes]" +"'SomeClass' declared with greater visibility than the type of its field 'SomeClass::member' [-Wattributes]" ============================================================================================================ This error typically indicates that you are compiling without the required @@ -169,8 +167,8 @@ can be changed, but even if it isn't it is not always enough to guarantee complete independence of the symbols involved when not using ``-fvisibility=hidden``. -Additionally, ``-fvisiblity=hidden`` can deliver considerably binary size -savings. (See the following section for more details). +Additionally, ``-fvisibility=hidden`` can deliver considerably binary size +savings. (See the following section for more details.) .. _`faq:symhidden`: @@ -180,7 +178,7 @@ How can I create smaller binaries? To do its job, pybind11 extensively relies on a programming technique known as *template metaprogramming*, which is a way of performing computation at compile -time using type information. Template metaprogamming usually instantiates code +time using type information. Template metaprogramming usually instantiates code involving significant numbers of deeply nested types that are either completely removed or reduced to just a few instructions during the compiler's optimization phase. However, due to the nested nature of these types, the resulting symbol @@ -222,20 +220,6 @@ In addition to decreasing binary size, ``-fvisibility=hidden`` also avoids potential serious issues when loading multiple modules and is required for proper pybind operation. See the previous FAQ entry for more details. -Working with ancient Visual Studio 2008 builds on Windows -========================================================= - -The official Windows distributions of Python are compiled using truly -ancient versions of Visual Studio that lack good C++11 support. Some users -implicitly assume that it would be impossible to load a plugin built with -Visual Studio 2015 into a Python distribution that was compiled using Visual -Studio 2008. However, no such issue exists: it's perfectly legitimate to -interface DLLs that are built with different compilers and/or C libraries. -Common gotchas to watch out for involve not ``free()``-ing memory region -that that were ``malloc()``-ed in another shared library, using data -structures with incompatible ABIs, and so on. pybind11 is very careful not -to make these types of mistakes. - How can I properly handle Ctrl-C in long-running functions? =========================================================== @@ -289,27 +273,7 @@ Conflicts can arise, however, when using pybind11 in a project that *also* uses the CMake Python detection in a system with several Python versions installed. This difference may cause inconsistencies and errors if *both* mechanisms are -used in the same project. Consider the following CMake code executed in a -system with Python 2.7 and 3.x installed: - -.. code-block:: cmake - - find_package(PythonInterp) - find_package(PythonLibs) - find_package(pybind11) - -It will detect Python 2.7 and pybind11 will pick it as well. - -In contrast this code: - -.. code-block:: cmake - - find_package(pybind11) - find_package(PythonInterp) - find_package(PythonLibs) - -will detect Python 3.x for pybind11 and may crash on -``find_package(PythonLibs)`` afterwards. +used in the same project. There are three possible solutions: @@ -320,7 +284,8 @@ There are three possible solutions: COMPONENTS Interpreter Development)`` on modern CMake (3.12+, 3.15+ better, 3.18.2+ best). Pybind11 in these cases uses the new CMake FindPython instead of the old, deprecated search tools, and these modules are much better at - finding the correct Python. + finding the correct Python. If FindPythonLibs/Interp are not available + (CMake 3.27+), then this will be ignored and FindPython will be used. 3. Set ``PYBIND11_NOPYTHON`` to ``TRUE``. Pybind11 will not search for Python. However, you will have to use the target-based system, and do more setup yourself, because it does not know about or include things that depend on |