package com.dragome.forms.bindings.client.command;
import com.dragome.forms.bindings.client.interceptor.Interceptor;
import com.dragome.forms.bindings.client.value.ValueModel;
import com.dragome.forms.bindings.extra.user.client.Command;
/**
* A UiCommand is a {@link Command} that also knows it's enabled state and can be bound to buttons.
* @see #enabled()
* @see TemporalUiCommand
* @see AsyncUiCommand
* @see AbstractUiCommand
* @see IncrementalUiCommand
* @see DelegatingUiCommand
*/
public interface UiCommand extends Command
{
/**
* Returns a ValueModel representing the enabled state of this command.
* @return a ValueModel representing the enabled state of this command.
*/
ValueModel<Boolean> enabled();
/**
* Adds an interceptor to run before the command executes. The interceptor <b>must</b> invoke
* {@link com.pietschy.gwt.pectin.client.interceptor.Invocation#proceed()} or execute {@link com.pietschy.gwt.pectin.client.interceptor.Invocation#getProceedCommand()}
* for the execution to proceed. Failure to do so will effectively abort the execution. In reality
* it's a case of a silent abort since the command is not notified of the interception.
* <p>
* As such it it imperative that interceptors be tested to ensure they always execute the proceed
* command if they don't want the execution to simple stop without further ado.
* <p>
* Of special interest is the case where onNextCall().onXyz(..) has been used and an interceptor
* chooses not to proceed. In this case the events will never be fired.
* <p>
* Notes to self: In order for other parties to be notified of cancellation then the Invocation would need
* to provide a cancel or abort method. The main issue with this is that failing to call it will still abort
* the execution. I.e. abort is equivalent to not calling proceed. There are a pile of bugs waiting to happen
* if I add an Invocation.abort() methods and onAborting(..) style events when I can't guarantee they'll be called.
*
* @param interceptor the interceptor to add.
*/
void interceptUsing(Interceptor interceptor);
Events always();
Events onNextCall();
}