versw(3) [osf1 man page]

versw(3)						     Library Functions Manual							  versw(3)

NAME

       versw,  VERSW - Check the status of an operating system version switch on a single cluster member to determine whether the calling applica-
       tion can enable new features that are incompatible with the old version of the operating system

LIBRARY

       Standard C Library (libc.so, libc.a)

SYNOPSIS

       #include <sys/versw.h>

       #include <sys/clu.h>

       int VERSW();

       int versw (
	       ulong high_vers,
	       ulong low_vers );

PARAMETERS

       Most significant ulong of new version ID.

       Least significant ulong of new version ID.

DESCRIPTION

       The VERSW() macro and versw() function check the status of a version switch on a single cluster member to  determine  whether  the  calling
       application  can  enable  new features that are incompatible with the old version of the operating system. Applications can use the VERSW()
       macro to enable new features on cluster members participating in a rolling upgrade.

       The versw() function examines the versw_transition attribute of the generic subsystem of the member's /etc/sysconfigtab file  and  compares
       the  specified  high_vers and low_vers parameters to the new version of the running kernel. It then compares these parameters to the active
       version of the running kernel. The VERSW() macro provides a wrapper for the versw()  function.  Because	the  VERSW()  macro  automatically
       extracts  the high and low version values from /usr/sys/conf/version.id, we recommend that you use it rather than call the versw() function
       directly.

RETURN VALUES

       Upon completion, the VERSW() macro and versw() function return one of the following values: A version switch is in progress and the  speci-
       fied  new  version  is greater than the active version of the running kernel. The calling application should disable new, incompatible fea-
       tures and respond to all requests for such features with an error condition.  A version switch is in progess and the specified new  version
       is  less  than  or equal to new version of the running kernel, or a version switch is not in progress and the specified new version is less
       than or equal to the active version of the running kernel. The application can safely enable, and entertain requests for, all new features.
       A  version  switch  is in progress  and the specified new version is greater than the active version of the running kernel. The application
       should disable new, incompatible features. Although the application should respond to all requests for such  features  originating  on  the
       local  member with an error condition, it should be prepared to handle requests for new, incompatible features originating from other clus-
       ter members with grace and elan.

EXAMPLES

       #include <stdio.h> #include <sys/versw.h> #include <sys/clu.h> main() {
	       if(VERSW() == VERSW_ENABLE)
		       printf("Enable new features
");
	       else    printf("Disable new features
");
	       endif }

FILES

       Rolling upgrade blocking conditions directory.  Version switch header file.  High and low version values used by VERSW() macro.

RELATED INFORMATION

       Functions: clu_is_member(3), clu_get_info(3)

       Commands: versw(8)

       delim off

																	  versw(3)

feature(3pm)						 Perl Programmers Reference Guide					      feature(3pm)

NAME

       feature - Perl pragma to enable new features

SYNOPSIS

	   use feature qw(switch say);
	   given ($foo) {
	       when(1) 	 { say "$foo == 1" }
	       when ([2,3])	 { say "$foo == 2 || $foo == 3" }
	       when (/^a[bc]d$/) { say "$foo eq 'abd' || $foo eq 'acd'" }
	       when ($_ > 100)	 { say "$foo > 100" }
	       default		 { say "None of the above" }
	   }

	   use feature ':5.10'; # loads all features available in perl 5.10

DESCRIPTION

       It is usually impossible to add new syntax to Perl without breaking some existing programs. This pragma provides a way to minimize that
       risk. New syntactic constructs, or new semantic meanings to older constructs, can be enabled by "use feature 'foo'", and will be parsed
       only when the appropriate feature pragma is in scope.

   Lexical effect
       Like other pragmas ("use strict", for example), features have a lexical effect. "use feature qw(foo)" will only make the feature "foo"
       available from that point to the end of the enclosing block.

	   {
	       use feature 'say';
	       say "say is available here";
	   }
	   print "But not here.
";

   "no feature"
       Features can also be turned off by using "no feature "foo"". This too has lexical effect.

	   use feature 'say';
	   say "say is available here";
	   {
	       no feature 'say';
	       print "But not here.
";
	   }
	   say "Yet it is here.";

       "no feature" with no features specified will turn off all features.

   The 'switch' feature
       "use feature 'switch'" tells the compiler to enable the Perl 6 given/when construct.

       See "Switch statements" in perlsyn for details.

   The 'say' feature
       "use feature 'say'" tells the compiler to enable the Perl 6 "say" function.

       See "say" in perlfunc for details.

   the 'state' feature
       "use feature 'state'" tells the compiler to enable "state" variables.

       See "Persistent Private Variables" in perlsub for details.

   the 'unicode_strings' feature
       "use feature 'unicode_strings'" tells the compiler to treat all strings outside of "use locale" and "use bytes" as Unicode. It is available
       starting with Perl 5.11.3.

       See "The "Unicode Bug"" in perlunicode for details.

FEATURE BUNDLES

       It's possible to load a whole slew of features in one go, using a feature bundle. The name of a feature bundle is prefixed with a colon, to
       distinguish it from an actual feature. At present, the only feature bundle is "use feature ":5.10"" which is equivalent to "use feature
       qw(switch say state)".

       Specifying sub-versions such as the 0 in 5.10.0 in feature bundles has no effect: feature bundles are guaranteed to be the same for all
       sub-versions.

IMPLICIT LOADING

       There are two ways to load the "feature" pragma implicitly :

       o   By using the "-E" switch on the command-line instead of "-e". It enables all available features in the main compilation unit (that is,
	   the one-liner.)

       o   By requiring explicitly a minimal Perl version number for your program, with the "use VERSION" construct, and when the version is
	   higher than or equal to 5.10.0. That is,

	       use 5.10.0;

	   will do an implicit

	       use feature ':5.10';

	   and so on. Note how the trailing sub-version is automatically stripped from the version.

	   But to avoid portability warnings (see "use" in perlfunc), you may prefer:

	       use 5.010;

	   with the same effect.

perl v5.12.5							    2012-11-03							      feature(3pm)