diff options
Diffstat (limited to 'pod/perlsyn.pod')
| -rw-r--r-- | pod/perlsyn.pod | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/pod/perlsyn.pod b/pod/perlsyn.pod index e41caee3ec..037ede1099 100644 --- a/pod/perlsyn.pod +++ b/pod/perlsyn.pod @@ -39,9 +39,9 @@ as the my if you expect to to be able to access those private variables. Declaring a subroutine allows a subroutine name to be used as if it were a list operator from that point forward in the program. You can declare a -subroutine without defining it by saying just +subroutine (prototyped to take one scalar parameter) without defining it by saying just: - sub myname; + sub myname ($); $me = myname $0 or die "can't get myname"; Note that it functions as a list operator though, not as a unary @@ -316,17 +316,19 @@ do it: See how much easier this is? It's cleaner, safer, and faster. It's cleaner because it's less noisy. It's safer because if code gets added -between the inner and outer loops later, you won't accidentally excecute -it because you've explicitly asked to iterate the other loop rather than -merely terminating the inner one. And it's faster because Perl executes a -C<foreach> statement more rapidly than it would the equivalent C<for> -loop. +between the inner and outer loops later on, the new code won't be +accidentally excecuted: the C<next> explicitly iterates the other loop +rather than merely terminating the inner one. And it's faster because +Perl executes a C<foreach> statement more rapidly than it would the +equivalent C<for> loop. =head2 Basic BLOCKs and Switch Statements A BLOCK by itself (labeled or not) is semantically equivalent to a loop that executes once. Thus you can use any of the loop control -statements in it to leave or restart the block. The C<continue> block +statements in it to leave or restart the block. (Note that this +is I<NOT> true in C<eval{}>, C<sub{}>, or contrary to popular belief C<do{}> blocks, +which do I<NOT> count as loops.) The C<continue> block is optional. The BLOCK construct is particularly nice for doing case @@ -419,10 +421,10 @@ for a C<do> block to return the proper value: $amode = do { if ($flag & O_RDONLY) { "r" } - elsif ($flag & O_WRONLY) { ($flag & O_APPEND) ? "w" : "a" } + elsif ($flag & O_WRONLY) { ($flag & O_APPEND) ? "a" : "w" } elsif ($flag & O_RDWR) { if ($flag & O_CREAT) { "w+" } - else { ($flag & O_APPEND) ? "r+" : "a+" } + else { ($flag & O_APPEND) ? "a+" : "r+" } } }; @@ -456,15 +458,15 @@ pretend that the other subroutine had been called in the first place propagated to the other subroutine.) After the C<goto>, not even caller() will be able to tell that this routine was called first. -In almost cases like this, it's usually a far, far better idea to use the -structured control flow mechanisms of C<next>, C<last>, or C<redo> insetad +In almost all cases like this, it's usually a far, far better idea to use the +structured control flow mechanisms of C<next>, C<last>, or C<redo> instead of resorting to a C<goto>. For certain applications, the catch and throw pair of C<eval{}> and die() for exception processing can also be a prudent approach. =head2 PODs: Embedded Documentation Perl has a mechanism for intermixing documentation with source code. -If while expecting the beginning of a new statement, the compiler +While it's expecting the beginning of a new statement, if the compiler encounters a line that begins with an equal sign and a word, like this =head1 Here There Be Pods! |