--- Guard/Guard.pm	2008/12/13 17:50:29	1.3
+++ Guard/Guard.pm	2008/12/13 18:51:19	1.11
@@ -4,7 +4,16 @@
 
 =head1 SYNOPSIS
 
- use Guard;
+   use Guard;
+   
+   # temporarily chdir to "/etc" directory, but make sure
+   # to go back to "/" no matter how myfun exits:
+   sub myfun {
+      scope_guard { chdir "/" };
+      chdir "/etc";
+   
+      call_function_that_might_die_or_other_fun_stuff;
+   }
 
 =head1 DESCRIPTION
 
@@ -45,11 +54,14 @@
 Registers a block that is executed when the current scope (block,
 function, method, eval etc.) is exited.
 
+See the EXCEPTIONS section for an explanation of how exceptions
+(i.e. C<die>) are handled inside guard blocks.
+
 The description below sounds a bit complicated, but that's just because
 C<scope_guard> tries to get even corner cases "right": the goal is to
 provide you with a rock solid clean up tool.
 
-This is similar to this code fragment:
+The behaviour is similar to this code fragment:
 
    eval ... code following scope_guard ...
    {
@@ -62,17 +74,26 @@
 Except it is much faster, and the whole thing gets executed even when the
 BLOCK calls C<exit>, C<goto>, C<last> or escapes via other means.
 
-See B<EXCEPTIONS>, below, for an explanation of exception handling
-(C<die>) within guard blocks.
-
-Example: Temporarily change the directory to F</etc> and make sure it's
-set back to F</> when the function returns:
-
-   sub dosomething {
-      scope_guard { chdir "/" };
-      chdir "/etc";
+If multiple BLOCKs are registered to the same scope, they will be executed
+in reverse order. Other scope-related things such as C<local> are managed
+via the same mechanism, so variables C<local>ised I<after> calling
+C<scope_guard> will be restored when the guard runs.
+
+Example: temporarily change the timezone for the current process,
+ensuring it will be reset when the C<if> scope is exited:
+
+   use Guard;
+   use POSIX ();
+
+   if ($need_to_switch_tz) {
+      # make sure we call tzset after $ENV{TZ} has been restored
+      scope_guard { POSIX::tzset };
+
+      # localise after the scope_guard, so it gets undone in time
+      local $ENV{TZ} = "Europe/London";
+      POSIX::tzset;
 
-      ...
+      # do something with the new timezone
    }
 
 =item my $guard = guard BLOCK
@@ -84,18 +105,21 @@
 
 The returned object can be copied as many times as you want.
 
-See B<EXCEPTIONS>, below, for an explanation of exception handling
-(C<die>) within guard blocks.
+See the EXCEPTIONS section for an explanation of how exceptions
+(i.e. C<die>) are handled inside guard blocks.
 
 Example: acquire a Coro::Semaphore for a second by registering a
-timer. The timer callback references the guard used to unlock it again.
+timer. The timer callback references the guard used to unlock it
+again. (Please ignore the fact that C<Coro::Semaphore> has a C<guard>
+method that does this already):
 
+   use Guard;
    use AnyEvent;
    use Coro::Semaphore;
 
    my $sem = new Coro::Semaphore;
 
-   sub lock_1s {
+   sub lock_for_a_second {
       $sem->down;
       my $guard = guard { $sem->up };
 
@@ -111,7 +135,9 @@
 $sem->down >> in the callback is that you can opt not to create the timer,
 or your code can throw an exception before it can create the timer, or you
 can create multiple timers or other event watchers and only when the last
-one gets executed will the lock be unlocked.
+one gets executed will the lock be unlocked. Using the C<guard>, you do
+not have to worry about catching all the places where you have to unlock
+the semaphore.
 
 =item Guard::cancel $guard
 
@@ -130,7 +156,7 @@
 
 =head1 EXCEPTIONS
 
-Guard blocks should not normally throw exceptions (e.g. C<die>), after
+Guard blocks should not normally throw exceptions (that is, C<die>). After
 all, they are usually used to clean up after such exceptions. However, if
 something truly exceptional is happening, a guard block should be allowed
 to die. Also, programming errors are a large source of exceptions, and the
@@ -157,8 +183,8 @@
 
 =head1 THANKS
 
-To Marco Maisenhelder, who reminded me of the C<$Guard::DIED> solution to
-the problem of exceptions.
+Thanks to Marco Maisenhelder, who reminded me of the C<$Guard::DIED>
+solution to the problem of exceptions.
 
 =cut