oaDesign Observer Notification and Binding

OpenAccess calls various callback functions when you open, reopen, revert, save, or purge a design. As with all callbacks, an application registers the desire to receive these callbacks by creating its own class that is derived from the callback class defined in the API. The application then constructs an instance of the derived callback class. The constructor registers the callback instance, and the database calls the virtual functions it has defined when the appropriate events occur.

The callbacks discussed here are the functions on the oaObserver<oaDesign> class. The application must create a class derived from oaObserver<oaDesign>, then implement the virtual functions such as onFirstOpen or onPreSave.

oaDesign Notifications

This table shows where each of the oaObserver<oaDesign> functions are invoked by listing a pair of oaDesign operations (first and second function calls on a given design) and showing the functions (callbacks) that will be triggered by those operations.

Key:	`w`	write
	`a`	append
	`r`	read

Action	Mode Used	Callbacks	Action	Mode used	Callback	Final Mode	Resulting Status
- First call on a given design -			- Second call on the given design -
open	w a r	onFirstOpen	close		onPurge
open	w	onFirstOpen	open	w r		w	No change in database
open	w	onFirstOpen	open	a	onPreReopen onPostReOpen	a	No change in database
open	a	onFirstOpen	open	a r		a	No change in database
open	a	onFirstOpen	open	w	onPreReopen onTruncate onPostReOpen	w	Database contents discarded
open	r	onFirstOpen	open	r		r
open	r	onFirstOpen	open	a	onPreReopen onPostReOpen	a	No change in database
open	r	onFirstOpen	open	w	onPreReopen onTruncate onPostReOpen	w	Database contents discarded
open	w a r	onFirstOpen	reopen	w a r		w a	If reopened in same mode
open	w	onFirstOpen	reopen	a	onPreReopen onPostReopen	a	No change in database
open	w a	onFirstOpen	reopen	r	onPreReopen onTruncate onFirstOpen onPostReopen	r	Reread from disk
open	a	onFirstOpen	reopen	w	onPreReopen onTruncate onPostReopen	w	Database contents discarded
open	r	onFirstOpen	reopen	w	onPreReopen onTruncate onPostReopen	w	Database contents discarded
open	r	onFirstOpen	reopen	a	onPreReopen onPostReopen	a	No change in database
open	r	onFirstOpen	reopen	r
open	w a	onFirstOpen	save		onPreSave onPostSave	a	Disk file changed
open	w a r	onFirstOpen	purge		onPurge	w a r	No change in mode
open	w a r	onFirstOpen	revert		onTruncate onFirstOpen	w a r	Reread from disk Database contents discarded
open	w a r	onFirstOpen	saveAs		onPreSaveAs onPostSaveAs	w a r	No change in mode No change in database

Binding

Binding is defined as connecting an object in one database to a related object in another database. When binding is done, the first object is represented in memory with a pointer to the object to which it is bound.

Binding occurs between Design databases and a Tech database for numerous types of objects. For example, oaViaHeader::getViaDef requires a binding between these two objects.

The current version of OpenAccess always binds a cross-database reference if the referenced object is in memory. Hence, when an oaDesign is first opened, all instances and instHeaders that point to it are bound. In addition, all the instTerms on those instances are bound if a corresponding Terminal exists on the newly-read master.

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