Craig Ringer wrote:
> Igor wrote:
> > Hi All,
> >
> > Is there an easy way to add c++ files to my simple pgsql module ? My
> > Makefile
> > is as follows -
> >
> > ===
> > MODULES = pg_uservars
> > DATA_built = pg_uservars.sql
> > PGXS := $(shell pg_config --pgxs)
> > include $(PGXS)
> > ===
> >
> > I've got "pg_uservars.c" and "hv.cc" and I'd like to compile hv.cc via g++.
> > I'm aware of c++ name [de]mangling, just looking if there's a standard way
> > of
> > using C++ when it comes to pgxs.
>
> It should "just work". Simply make sure to follow the usual rules for
> calling into C++ code from C and vice versa:
>
> - Use "extern C" linkage for all functions that must be accessible by
> dlopen(), and preferably also for any functions that you might take
> a function pointer to and pass to C code
>
> - Never return new()'d memory that might be free()'d by the C code; use
> malloc()
>
> - Never delete() memory that was malloc()'d by the C code; use free()
>
> - Never let an exception propagate into the C code; use a catch-all
> block at the top level of all "extern C" functions
>
> ... and probably other things I've missed.
That is great new information. I have created a new documentation
section called "Using C++ for Extensibility", and listed you as the
author in the CVS commit; patch attached. Thanks.
--
Bruce Momjian <br...@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ None of us is going to be here forever. +
Index: doc/src/sgml/extend.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/extend.sgml,v
retrieving revision 1.38
diff -c -c -r1.38 extend.sgml
*** doc/src/sgml/extend.sgml 3 Apr 2010 07:22:53 -0000 1.38
--- doc/src/sgml/extend.sgml 1 Jun 2010 02:29:31 -0000
***************
*** 273,276 ****
--- 273,322 ----
&xoper;
&xindex;
+ <sect1 id="extend-how">
+ <title>Using C++ for Extensibility</title>
+
+ <indexterm zone="extend-Cpp">
+ <primary>C++</primary>
+ </indexterm>
+
+ <para>
+ It is possible to use a compiler in C++ mode to build
+ <productname>PostgreSQL</productname> extensions; you must simply
+ follow the standard methods for dynamically linking to C executables:
+
+ <itemizedlist>
+ <listitem>
+ <para>
+ Use <literal>extern C</> linkage for all functions that must
+ be accessible by <function>dlopen()</>. This is also necessary
+ for any functions that might be passed as pointers between
+ the backend and C++ code.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ Use <function>malloc()</> to allocate any memory that might be
+ freed by the backend C code (don't pass <function>new()</>-allocated
+ memory).
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ Use <function>free()</> to free memory allocated by the backend
+ C code (do not use <function>delete()</> for such cases).
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ Prevent exceptions from propagating into the C code (use a
+ catch-all block at the top level of all <literal>extern C</>
+ functions).
+ </para>
+ </listitem>
+ </itemizedlist>
+ </para>
+
+ </sect1>
+
</chapter>
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