Is this a new usage in PL/SQL?

Question

Hi friends,
Today I've tested new features in 11G, and read the Document "Oracle Database 11g: The Top New Features for DBAs and Developers" and when I come to page 226 chapter PL/SQL Performance, I see this code as follows:
alter session set plsql_warnings = ‘enable:all, disable:06002, disable:06005, disable:06006,
disable:06010’
alter session set plsql_ccflags = ‘simple:false’
create package gcd_test is
procedure time_it;
end gcd_test;
create package body gcd_test is
$if $$simple $then
subtype my_integer is simple_integer;
simple constant times.simple%type := ‘y’;
$else
subtype my_integer is pls_integer not null;
simple constant times.simple%type := ‘n’;
$end
Frankly I have never seen that package body can be defined like this...
the dollar sign with the logic operators, never seen in PL/SQL reference book and then I tested in 11G, it won't cause any error.
I can't remember this usage in any document...
so if anybody knows about that, I need your help~
Edited by: user12977032 on Jul 2, 2010 12:09 AM

Answer 1

user12977032 wrote:
I mean the code is like some way to define variables dynamically, or following some rules.Not really. This new feature is a standard feature in most compilers. It allows you to define and set compiler flags and variables and perform conditional compilation.
For example, you may have a PL/SQL package that is used on Standard Edition (SE) and Enterprise Edition (EE). However, you would like to use a EE feature that is not available on SE (SE for example requires a slower method to be used).
With conditional compiling you can define a code block that needs to be compiled for EE versions and a different code block that needs to be compiled for SE. Thus you have source code that can be compiled optimally for that server version it is being compiled on.
This feature has existed for many years in compilers ranging from C to Delphi. And has been sorely missing from the PL/SQL parser and compiler.