diff options
Diffstat (limited to 'pod/perlfunc.pod')
| -rw-r--r-- | pod/perlfunc.pod | 51 |
1 files changed, 27 insertions, 24 deletions
diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod index eb7276a3b4..c4de4a39ae 100644 --- a/pod/perlfunc.pod +++ b/pod/perlfunc.pod @@ -35,11 +35,11 @@ operator or unary operator, and precedence does matter. And whitespace between the function and left parenthesis doesn't count--so you need to be careful sometimes: - print 1+2+3; # Prints 6. - print(1+2) + 3; # Prints 3. - print (1+2)+3; # Also prints 3! - print +(1+2)+3; # Prints 6. - print ((1+2)+3); # Prints 6. + print 1+2+4; # Prints 7. + print(1+2) + 4; # Prints 3. + print (1+2)+4; # Also prints 3! + print +(1+2)+4; # Prints 7. + print ((1+2)+4); # Prints 7. If you run Perl with the B<-w> switch it can warn you about this. For example, the third line above produces: @@ -1123,21 +1123,22 @@ value is taken as the name of the filehandle. =item flock FILEHANDLE,OPERATION Calls flock(2), or an emulation of it, on FILEHANDLE. Returns TRUE for -success, FALSE on failure. Will produce a fatal error if used on a -machine that doesn't implement flock(2), fcntl(2) locking, or lockf(3). -flock() is Perl's portable file locking interface, although it will lock -only entire files, not records. +success, FALSE on failure. Produces a fatal error if used on a machine +that doesn't implement flock(2), fcntl(2) locking, or lockf(3). flock() +is Perl's portable file locking interface, although it locks only entire +files, not records. OPERATION is one of LOCK_SH, LOCK_EX, or LOCK_UN, possibly combined with LOCK_NB. These constants are traditionally valued 1, 2, 8 and 4, but -you can use the symbolic names if you pull them in with an explicit -request to the Fcntl module. The names can be requested as a group with -the :flock tag (or they can be requested individually, of course). -LOCK_SH requests a shared lock, LOCK_EX requests an exclusive lock, and -LOCK_UN releases a previously requested lock. If LOCK_NB is added to -LOCK_SH or LOCK_EX then flock() will return immediately rather than -blocking waiting for the lock (check the return status to see if you got -it). +you can use the symbolic names if import them from the Fcntl module, +either individually, or as a group using the ':flock' tag. LOCK_SH +requests a shared lock, LOCK_EX requests an exclusive lock, and LOCK_UN +releases a previously requested lock. If LOCK_NB is added to LOCK_SH or +LOCK_EX then flock() will return immediately rather than blocking +waiting for the lock (check the return status to see if you got it). + +To avoid the possibility of mis-coordination, Perl flushes FILEHANDLE +before (un)locking it. Note that the emulation built with lockf(3) doesn't provide shared locks, and it requires that FILEHANDLE be open with write intent. These @@ -1436,9 +1437,11 @@ Returns the socket option requested, or undefined if there is an error. =item glob -Returns the value of EXPR with filename expansions such as a shell -would do. This is the internal function implementing the <*.c> -operator, except it's easier to use. If EXPR is omitted, $_ is used. +Returns the value of EXPR with filename expansions such as a shell would +do. This is the internal function implementing the C<E<lt>*.cE<gt>> +operator, but you can use it directly. If EXPR is omitted, $_ is used. +The C<E<lt>*.cE<gt>> operator is discussed in more detail in +L<perlop/"I/O Operators">. =item gmtime EXPR @@ -2299,7 +2302,7 @@ Generalized quotes. See L<perlop>. =item quotemeta -Returns the value of EXPR with with all non-alphanumeric +Returns the value of EXPR with all non-alphanumeric characters backslashed. (That is, all characters not matching C</[A-Za-z_0-9]/> will be preceded by a backslash in the returned string, regardless of any locale settings.) @@ -2499,9 +2502,9 @@ so you'll probably want to use them instead. See L</my>. =item return LIST -Returns from a subroutine or eval with the value specified. (Note that -in the absence of a return a subroutine or eval() will automatically -return the value of the last expression evaluated.) +Returns from a subroutine, eval(), or do FILE with the value specified. +(Note that in the absence of a return, a subroutine, eval, or do FILE +will automatically return the value of the last expression evaluated.) =item reverse LIST |