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Diffstat (limited to 'doc/src/sgml/extend.sgml')
| -rw-r--r-- | doc/src/sgml/extend.sgml | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/doc/src/sgml/extend.sgml b/doc/src/sgml/extend.sgml index f3850b391e0..8d5b9d0c836 100644 --- a/doc/src/sgml/extend.sgml +++ b/doc/src/sgml/extend.sgml @@ -200,13 +200,13 @@ <para> 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. + 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> @@ -217,15 +217,16 @@ data type, but in any given call they must all be the <emphasis>same</emphasis> actual type. Each position declared as <type>anyarray</type> can have any array data type, - but similarly they must all be the same type. If there are + but similarly they must all be the same type. And similarly, + positions declared as <type>anyrange</type> must all be the same range + type. Furthermore, if there are positions declared <type>anyarray</type> and others declared <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 + 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 |