diff options
Diffstat (limited to 'doc/src/sgml/extend.sgml')
| -rw-r--r-- | doc/src/sgml/extend.sgml | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/doc/src/sgml/extend.sgml b/doc/src/sgml/extend.sgml index 7079db3ed3..f3850b391e 100644 --- a/doc/src/sgml/extend.sgml +++ b/doc/src/sgml/extend.sgml @@ -198,14 +198,15 @@ </indexterm> <para> - Four pseudo-types of special interest are <type>anyelement</>, - <type>anyarray</>, <type>anynonarray</>, and <type>anyenum</>, - which are collectively called <firstterm>polymorphic types</>. - Any function declared using these types is said to be - a <firstterm>polymorphic function</>. A polymorphic function can - operate on many different data types, with the specific data type(s) - being determined by the data types actually passed to it in a particular - call. + Five pseudo-types of special interest are <type>anyelement</>, + <type>anyarray</>, <type>anynonarray</>, <type>anyenum</>, + and <type>anyrange</>, which are collectively + called <firstterm>polymorphic types</>. Any function declared + using these types is said to be a <firstterm>polymorphic + function</>. A polymorphic function can operate on many + different data types, with the specific data type(s) being + determined by the data types actually passed to it in a + particular call. </para> <para> @@ -221,6 +222,11 @@ <type>anyelement</type>, the actual array type in the <type>anyarray</type> positions must be an array whose elements are the same type appearing in the <type>anyelement</type> positions. + Similarly, if there are positions declared <type>anyrange</type> + and others declared + <type>anyelement</type>, the actual range type in the + <type>anyrange</type> positions must be a range whose subtype is + the same type appearing in the <type>anyelement</type> positions. <type>anynonarray</> is treated exactly the same as <type>anyelement</>, but adds the additional constraint that the actual type must not be an array type. |