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| -rw-r--r-- | Doc/ext/ext.tex | 37 |
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diff --git a/Doc/ext/ext.tex b/Doc/ext/ext.tex index 2aef7e8..d54b78c 100644 --- a/Doc/ext/ext.tex +++ b/Doc/ext/ext.tex @@ -2111,4 +2111,41 @@ will need to write the main program in \Cpp{}, and use the \Cpp{} compiler to compile and link your program. There is no need to recompile Python itself using \Cpp{}. + +\section{Linking Requirements + \label{link-reqs}} + +While the \program{configure} script shipped with the Python sources +will correctly build Python to export the symbols needed by +dynamically linked extensions, this is not automatically inherited by +applications which embed the Python library statically, at least on +\UNIX. This is an issue when the application is linked to the static +runtime library (\file{libpython.a}) and needs to load dynamic +extensions (implemented as \file{.so} files). + +The problem is that some entry points are defined by the Python +runtime solely for extension modules to use. If the embedding +application does not use any of these entry points, some linkers will +not include those entries in the symbol table of the finished +executable. Some additional options are needed to inform the linker +not to remove these symbols. + +Determining the right options to use for any given platform can be +quite difficult, but fortunately the Python configuration already has +those values. To retrieve them from an installed Python interpreter, +start an interactive interpreter and have a short session like this: + +\begin{verbatim} +>>> import distutils.sysconfig +>>> distutils.sysconfig.LINKFORSHARED +'-Xlinker -export-dynamic' +\end{verbatim} +\refstmodindex{distutils.sysconfig} + +The contents of the string presented will be the options that should +be used. If the string is empty, there's no need to add any +additional options. The \constant{LINKFORSHARED} definition +corresponds to the variable of the same name in Python's top-level +\file{Makefile}. + \end{document} |