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Diffstat (limited to 'doc/src/sgml/xfunc.sgml')
| -rw-r--r-- | doc/src/sgml/xfunc.sgml | 54 |
1 files changed, 28 insertions, 26 deletions
diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml index 8d323c6879..ea446c9258 100644 --- a/doc/src/sgml/xfunc.sgml +++ b/doc/src/sgml/xfunc.sgml @@ -1,5 +1,5 @@ <!-- -$Header: /cvsroot/pgsql/doc/src/sgml/xfunc.sgml,v 1.73 2003/08/31 17:32:20 petere Exp $ +$Header: /cvsroot/pgsql/doc/src/sgml/xfunc.sgml,v 1.74 2003/09/11 21:42:20 momjian Exp $ --> <sect1 id="xfunc"> @@ -814,15 +814,15 @@ CREATE FUNCTION square_root(double precision) RETURNS double precision <para> To know how to write C-language functions, you need to know how - PostgreSQL internally represents base data types and how they can - be passed to and from functions. - Internally, <productname>PostgreSQL</productname> regards a - base type as a <quote>blob of memory</quote>. The user-defined - functions that you define over a type in turn define the - way that <productname>PostgreSQL</productname> can operate - on it. That is, <productname>PostgreSQL</productname> will - only store and retrieve the data from disk and use your - user-defined functions to input, process, and output the data. + <productname>PostgreSQL</productname> internally represents base + data types and how they can be passed to and from functions. + Internally, <productname>PostgreSQL</productname> regards a base + type as a <quote>blob of memory</quote>. The user-defined + functions that you define over a type in turn define the way that + <productname>PostgreSQL</productname> can operate on it. That + is, <productname>PostgreSQL</productname> will only store and + retrieve the data from disk and use your user-defined functions + to input, process, and output the data. </para> <para> @@ -1249,13 +1249,14 @@ CREATE FUNCTION concat_text(text, text) RETURNS text <para> Here, <replaceable>DIRECTORY</replaceable> stands for the - directory of the shared library file (for instance the PostgreSQL - tutorial directory, which contains the code for the examples used - in this section). (Better style would be to use just - <literal>'funcs'</> in the <literal>AS</> clause, after having - added <replaceable>DIRECTORY</replaceable> to the search path. - In any case, we may omit the system-specific extension for a - shared library, commonly <literal>.so</literal> or + directory of the shared library file (for instance the + <productname>PostgreSQL</productname> tutorial directory, which + contains the code for the examples used in this section). + (Better style would be to use just <literal>'funcs'</> in the + <literal>AS</> clause, after having added + <replaceable>DIRECTORY</replaceable> to the search path. In any + case, we may omit the system-specific extension for a shared + library, commonly <literal>.so</literal> or <literal>.sl</literal>.) </para> @@ -1483,15 +1484,16 @@ concat_text(PG_FUNCTION_ARGS) <para> Before we turn to the more advanced topics, we should discuss - some coding rules for PostgreSQL C-language functions. While it - may be possible to load functions written in languages other than - C into <productname>PostgreSQL</productname>, this is usually - difficult (when it is possible at all) because other languages, - such as C++, FORTRAN, or Pascal often do not follow the same - calling convention as C. That is, other languages do not pass - argument and return values between functions in the same way. - For this reason, we will assume that your C-language functions - are actually written in C. + some coding rules for <productname>PostgreSQL</productname> + C-language functions. While it may be possible to load functions + written in languages other than C into + <productname>PostgreSQL</productname>, this is usually difficult + (when it is possible at all) because other languages, such as + C++, FORTRAN, or Pascal often do not follow the same calling + convention as C. That is, other languages do not pass argument + and return values between functions in the same way. For this + reason, we will assume that your C-language functions are + actually written in C. </para> <para> |