NAME
Reflex::Role::Writing - add standard syswrite() behavior to a class
VERSION
version 0.060
SYNOPSIS
package OutputStreaming;
use Reflex::Role;
attribute_parameter handle => "handle";
callback_parameter cb_error => qw( on handle error );
method_parameter method_put => qw( put handle _ );
method_parameter method_stop => qw( stop handle _ );
method_parameter method_pause_writable => qw( _pause handle writable );
method_parameter method_resume_writable => qw( _resume handle writable );
method_parameter method_flush => qw( _flush handle writable );
role {
my $p = shift;
my $h = $p->handle();
my $cb_error = $p->cb_error();
with 'Reflex::Role::Writing' => {
handle => $h,
cb_error => $p->cb_error(),
method_put => $p->method_put(),
method_flush => $p->method_flush(),
method_pause_writable => $p->method_pause_writable(),
method_resume_writable => $p->method_resume_writable(),
};
with 'Reflex::Role::Writable' => {
handle => $h,
cb_ready => $p->method_flush(),
method_pause => $p->method_pause_writable(),
method_resume => $p->method_resume_writable(),
};DESCRIPTION
Reflex::Role::Readable implements a standard nonblocking sysread() feature so that it may be added to classes as needed.
There's a lot going on in the SYNOPSIS.
Reflex::Role::Writing defines methods that will perform non-blocking, buffered syswrite() on a named "handle". It has a single callback, "cb_error", that is invoked if syswrite() ever returns an error. It defines a method, "method_put", that is used to write new data to the handle---or buffer data if it can't be written immediately. "method_flush" is defined to flush buffered data when possible. The other methods, "method_pause_writable" and "method_resume_writable" aren't generated by this role. Rather, this role calls them to disable and re-enable background writes as needed.
Reflex::Role::Writable implements the other side of the Writable/Writing contract. It wastches a "handle" and invokes "cb_ready" whenever the opportunity to write new data arises. It defines a few methods, two of which allow the watcher to be paused and resumed.
The Writable and Writing roles are generally complementary. Their defaults allow them to fit together more succinctly than (and less understandably than) shown in the SYNOPSIS.
Attribute Role Parameters
handle
handle names an attribute holding the handle to be watched for writable readiness.
Callback Role Parameters
cb_error
cb_error names the $self method that will be called whenever the stream produces an error. By default, this method will be the catenation of "on_", the handle name, and "_error". As in on_XYZ_error(), if the handle is named "XYZ". The role defines a default callback that will emit an "error" event with cb_error()'s parameters, then will call stopped() so that streams managed by Reflex::Collection will be automatically cleaned up after stopping.
cb_error callbacks receive two parameters, $self and an anonymous hashref of named values specific to the callback. Reflex error callbacks include three standard values. errfun contains a single word description of the function that failed. errnum contains the numeric value of $! at the time of failure. errstr holds the stringified version of $!.
Values of $! are passed as parameters since the global variable may change before the callback can be invoked.
When overriding this callback, please be sure to call stopped(), which is provided by Reflex::Role::Collectible. Calling stopped() is vital for collectible objects to be released from memory when managed by Reflex::Collection.
Method Role Parameters
method_put
This role genrates a method to write data to the handle in the "handle" attribute. The "method_put" role parameter specifies the name of this generated method. The method's name will be "put_${handle_name}" by default.
The generated method will immediately attempt to write data if the role's buffer is empty. If the buffer contains data, however, then the new data will be appended there to maintain the ordering of data in the stream. Any data that could not be written during "method_put" will be added to the buffer as well.
The "method_put" implementation will call "method_resume_writable" to enable background flushing, as needed.
The generated "method_put" will return the number of octets remaining in the buffer, or 0 if the buffer is empty. It will return undef if syswrite() failed, and $! will be set to the reason for the failure.
method_flush
This role generates a method to flush data that had to be buffered by previous "method_put" calls. This method will call "method_pause_writable" to disable background flushing if the buffer is fully flushed.
TODO
This role should probably not be concerned with pausing and resuming writability watchers. Rather, method_flush should return the state of the internal buffer so that the caller can do the right thing---whatever that may be.
EXAMPLES
TODO - I'm sure there are some.
SEE ALSO
Reflex Reflex::Role Reflex::Role::Writable Reflex::Role::Readable Reflex::Role::Streaming
"ACKNOWLEDGEMENTS" in Reflex "ASSISTANCE" in Reflex "AUTHORS" in Reflex "BUGS" in Reflex "BUGS" in Reflex "CONTRIBUTORS" in Reflex "COPYRIGHT" in Reflex "LICENSE" in Reflex "TODO" in Reflex