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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" "CPS::Governor" \- control the iteration of the "CPS" functions .SH "DESCRIPTION" .IX Header "DESCRIPTION" Objects based on this abstract class are used by the \f(CW\*(C`gk*\*(C'\fR variants of the \&\s-1CPS\s0 functions, to control their behavior. These objects are expected to provide a method, \f(CW\*(C`again\*(C'\fR, which the functions will use to re-invoke iterations of loops, and so on. By providing a different implementation of this method, governor objects can provide such behaviours as rate-limiting, asynchronisation or parallelism, and integration with event-based \s-1IO\s0 frameworks. .SH "CONSTRUCTOR" .IX Header "CONSTRUCTOR" .ie n .SS "$gov = CPS::Governor\->new" .el .SS "\f(CW$gov\fP = CPS::Governor\->new" .IX Subsection "$gov = CPS::Governor->new" Must be called on a subclass which implements the \f(CW\*(C`again\*(C'\fR method. Returns a new instance of a governor object in that class. .SH "SUBCLASS METHODS" .IX Header "SUBCLASS METHODS" Because this is an abstract class, instances of it can only be constructed on a subclass which implements the following methods: .ie n .SS "$gov\->again( $code, @args )" .el .SS "\f(CW$gov\fP\->again( \f(CW$code\fP, \f(CW@args\fP )" .IX Subsection "$gov->again( $code, @args )" Execute the function given in the \f(CW\*(C`CODE\*(C'\fR reference \f(CW$code\fR, passing in the arguments \f(CW@args\fR. If this is going to be executed immediately, it should be invoked using a tail-call directly by the \f(CW\*(C`again\*(C'\fR method, so that the stack does not grow arbitrarily. This can be achieved by, for example: .PP .Vb 2 \& @_ = @args; \& goto &$code; .Ve .PP Alternatively, the Sub::Call::Tail may be used to apply syntactic sugar, allowing you to write instead: .PP .Vb 3 \& use Sub::Call::Tail; \& ... \& tail $code\->( @args ); .Ve .SH "EXAMPLES" .IX Header "EXAMPLES" .SS "A Governor With A Time Delay" .IX Subsection "A Governor With A Time Delay" Consider the following subclass, which implements a \f(CW\*(C`CPS::Governor\*(C'\fR subclass that calls \f(CW\*(C`sleep()\*(C'\fR between every invocation. .PP .Vb 1 \& package Governor::Sleep \& \& use base qw( CPS::Governor ); \& \& sub new \& { \& my $class = shift; \& my ( $delay ) = @_; \& \& my $self = $class\->SUPER::new; \& $self\->{delay} = $delay; \& \& return $self; \& } \& \& sub again \& { \& my $self = shift; \& my $code = shift; \& \& sleep $self\->{delay}; \& \& # @args are still in @_ \& goto &$code; \& } .Ve .SH "SEE ALSO" .IX Header "SEE ALSO" .IP "\(bu" 4 Sub::Call::Tail \- Tail calls for subroutines and methods .SH "AUTHOR" .IX Header "AUTHOR" Paul Evans