Make clearer how arguments and return values in pl/perl are escaped. This is to clari...

diff --git a/doc/src/sgml/plperl.sgml b/doc/src/sgml/plperl.sgml
index 1be0ae5b8e50aef4b19218fb07b7c1e012a63dae..826088c9c5f1afb52f22e81ac5d6e81c70c35798 100644 (file)
--- a/doc/src/sgml/plperl.sgml
+++ b/doc/src/sgml/plperl.sgml
@@ -1,4 +1,4 @@
-
+
 
  
   PL/Perl - Perl Procedural Language
@@ -137,6 +137,36 @@ $$ LANGUAGE plperl;
    function is strict or not.
   
 
+  
+   Anything in a function argument that is not a reference is
+   a string, which is in the standard PostgreSQL 
+   external text representation for the relevant data type. In the case of
+   ordinary numeric or text types, Perl will just do the right thing and
+   the programmer will normally not have to worry about it. However, in
+   other cases the argument will need to be converted into a form that is 
+   more usable in Perl. For example, here is how to convert an argument of 
+   type bytea into unescaped binary 
+   data:
+
+
+    my $arg = shift;
+    $arg =~ s!\\(\d{3})!chr(oct($1))!ge;
+
+
+  
+
+  
+   Similarly, values passed back to PostgreSQL 
+   must be in the external text representation format. For example, here 
+   is how to escape binary data for a return value of type bytea:
+
+
+    $retval =~ s!([^ -~])!sprintf("\\%03o",ord($1))!ge;
+    return $retval;
+
+
+  
+
   
    Perl can return PostgreSQL arrays as
    references to Perl arrays.  Here is an example:
@@ -144,7 +174,7 @@ $$ LANGUAGE plperl;
 
 CREATE OR REPLACE function returns_array()
 RETURNS text[][] AS $$
-    return [['a"b','c,d'],['e\\f','g']];
+    return [['a"b','c,d'],['e\\f','g']];
 $$ LANGUAGE plperl;
 
 select returns_array();