}
Would print '1', because C<$foo> holds a reference to the I<original>
-C<$bar> -- the one that was stuffed away by C<local()> and which will be
+C<$bar>. The one that was stuffed away by C<local()> and which will be
restored when the block ends. Because variables are accessed through the
typeglob, you can use C<*foo = *bar> to create an alias which can be
localized. (But be aware that this means you can't have a separate
A C<BEGIN> code block is executed as soon as possible, that is, the moment
it is completely defined, even before the rest of the containing file (or
string) is parsed. You may have multiple C<BEGIN> blocks within a file (or
-eval'ed string) -- they will execute in order of definition. Because a C<BEGIN>
+eval'ed string); they will execute in order of definition. Because a C<BEGIN>
code block executes immediately, it can pull in definitions of subroutines
and such from other files in time to be visible to the rest of the compile
and run time. Once a C<BEGIN> has run, it is immediately undefined and any
code it used is returned to Perl's memory pool.
-It should be noted that C<BEGIN> and C<UNITCHECK> code blocks B<are>
-executed inside string C<eval()>'s. The C<CHECK> and C<INIT> code
-blocks are B<not> executed inside a string eval, which e.g. can be a
-problem in a mod_perl environment.
-
An C<END> code block is executed as late as possible, that is, after
perl has finished running the program and just before the interpreter
is being exited, even if it is exiting as a result of a die() function.
running something via C<system>).
X<$?>
+Inside of a C<END> block, the value of C<${^GLOBAL_PHASE}> will be
+C<"END">.
+
C<UNITCHECK>, C<CHECK> and C<INIT> code blocks are useful to catch the
transition between the compilation phase and the execution phase of
the main program.
C<(?{ })> construct in a regex, calls to C<do FILE>, C<require FILE>,
and code after the C<-e> switch on the command line.
+C<BEGIN> and C<UNITCHECK> blocks are not directly related to the phase of
+the interpreter. They can be created and executed during any phase.
+
C<CHECK> code blocks are run just after the B<initial> Perl compile phase ends
and before the run time begins, in LIFO order. C<CHECK> code blocks are used
in the Perl compiler suite to save the compiled state of the program.
+Inside of a C<CHECK> block, the value of C<${^GLOBAL_PHASE}> will be
+C<"CHECK">.
+
C<INIT> blocks are run just before the Perl runtime begins execution, in
"first in, first out" (FIFO) order.
+Inside of an C<INIT> block, the value of C<${^GLOBAL_PHASE}> will be C<"INIT">.
+
+The C<CHECK> and C<INIT> blocks in code compiled by C<require>, string C<do>,
+or string C<eval> will not be executed if they occur after the end of the
+main compilation phase; that can be a problem in mod_perl and other persistent
+environments which use those functions to load code at runtime.
+
When you use the B<-n> and B<-p> switches to Perl, C<BEGIN> and
C<END> work just as they do in B<awk>, as a degenerate case.
Both C<BEGIN> and C<CHECK> blocks are run when you use the B<-c>