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Add documentation for the new "dollar quoting" feature, and update existing

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examples to use dollar quoting when appropriate. Original patch from David
Fetter, additional work and editorializing by Neil Conway.
This commit is contained in:
Neil Conway
2004-05-16 23:22:08 +00:00
parent 2871f60f23
commit 8295c27c89
11 changed files with 371 additions and 253 deletions
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44
doc/src/sgml/plperl.sgml
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@@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/plperl.sgml,v 2.22 2003/12/14 00:10:32 neilc Exp $
$PostgreSQL: pgsql/doc/src/sgml/plperl.sgml,v 2.23 2004/05/16 23:22:06 neilc Exp $
-->
<chapter id="plperl">
@@ -46,11 +46,17 @@ $PostgreSQL: pgsql/doc/src/sgml/plperl.sgml,v 2.22 2003/12/14 00:10:32 neilc Exp
<para>
To create a function in the PL/Perl language, use the standard syntax:
<programlisting>
CREATE FUNCTION <replaceable>funcname</replaceable> (<replaceable>argument-types</replaceable>) RETURNS <replaceable>return-type</replaceable> AS '
CREATE FUNCTION <replaceable>funcname</replaceable>
(<replaceable>argument-types</replaceable>) RETURNS <replaceable>return-type</replaceable> AS $$
# PL/Perl function body
' LANGUAGE plperl;
$$ LANGUAGE plperl;
</programlisting>
The body of the function is ordinary Perl code.
The body of the function is ordinary Perl code. Since the body of
the function is treated as a string by
<productname>PostgreSQL</productname>, it can be specified using
dollar quoting (as shown above), or via the usual single quote
syntax (see <xref linkend="sql-syntax-strings"> for more
information).
</para>
<para>
@@ -65,10 +71,10 @@ CREATE FUNCTION <replaceable>funcname</replaceable> (<replaceable>argument-types
could be defined as:
<programlisting>
CREATE FUNCTION perl_max (integer, integer) RETURNS integer AS '
CREATE FUNCTION perl_max (integer, integer) RETURNS integer AS $$
if ($_[0] > $_[1]) { return $_[0]; }
return $_[1];
' LANGUAGE plperl;
$$ LANGUAGE plperl;
</programlisting>
</para>
@@ -88,7 +94,7 @@ CREATE FUNCTION perl_max (integer, integer) RETURNS integer AS '
rather than a null value:
<programlisting>
CREATE FUNCTION perl_max (integer, integer) RETURNS integer AS '
CREATE FUNCTION perl_max (integer, integer) RETURNS integer AS $$
my ($a,$b) = @_;
if (! defined $a) {
if (! defined $b) { return undef; }
@@ -97,7 +103,7 @@ CREATE FUNCTION perl_max (integer, integer) RETURNS integer AS '
if (! defined $b) { return $a; }
if ($a > $b) { return $a; }
return $b;
' LANGUAGE plperl;
$$ LANGUAGE plperl;
</programlisting>
</para>
@@ -119,10 +125,10 @@ CREATE TABLE employee (
bonus integer
);
CREATE FUNCTION empcomp(employee) RETURNS integer AS '
CREATE FUNCTION empcomp(employee) RETURNS integer AS $$
my ($emp) = @_;
return $emp->{''basesalary''} + $emp->{''bonus''};
' LANGUAGE plperl;
return $emp->{'basesalary'} + $emp->{'bonus'};
$$ LANGUAGE plperl;
SELECT name, empcomp(employee) FROM employee;
</programlisting>
@@ -136,12 +142,12 @@ SELECT name, empcomp(employee) FROM employee;
<tip>
<para>
Because the function body is passed as an SQL string literal to
<command>CREATE FUNCTION</command>, you have to escape single
quotes and backslashes within your Perl source, typically by
doubling them as shown in the above example. Another possible
approach is to avoid writing single quotes by using Perl's
extended quoting operators (<literal>q[]</literal>,
<literal>qq[]</literal>, <literal>qw[]</literal>).
<command>CREATE FUNCTION</command>, you have to use dollar quoting
or escape single quotes and backslashes within your Perl source,
typically by doubling them. Another possible approach is to avoid
writing single quotes by using Perl's extended quoting operators
(<literal>q[]</literal>, <literal>qq[]</literal>,
<literal>qw[]</literal>).
</para>
</tip>
</sect1>
@@ -226,11 +232,11 @@ SELECT name, empcomp(employee) FROM employee;
Here is an example of a function that will not work because file
system operations are not allowed for security reasons:
<programlisting>
CREATE FUNCTION badfunc() RETURNS integer AS '
CREATE FUNCTION badfunc() RETURNS integer AS $$
open(TEMP, ">/tmp/badfile");
print TEMP "Gotcha!\n";
return 1;
' LANGUAGE plperl;
$$ LANGUAGE plperl;
</programlisting>
The creation of the function will succeed, but executing it will not.
</para>