Object Manager Service |
Ver. 1.00 Contributed by Tim Roberts |
What
n_cst_object_factory - Object Manager Service
Why
The PFC does not address an applications need to share business objects at a global, shared or instance level. The object manager will allow any other object (window, nonvisual, visual, etc.) to share business objects with each other.An example of how this would be useful:
Lets say that a system uses account information in multiple places and can be updated by multiple things (windows, datawindows, etc.). Being a good OO person, you create an account object to encapsulate all of the account methods. But you may have an implementation problem: what happens if one window needs to know if another window (or any place else) made a modification to your account. Some ugly solutions have been defining the object as global or hardcoding window references or even posting a message for all objects to re-retrieve themselves. Using the object factory, you can have each object create a shared instance of the object that is shared between all of them - one update anywhere is instantly available to all others. You can even have multiple shared account objects by assigning each a unique sharename (say the account number or name).
Some of its capabilities:
- Have a single globally shared object (useful for DDDW caches - insert a row and all shared DDDW automatically updated)
- Have multiple shared versions of a single object (useful for business objects like employee, account, etc.)
- Have a single globally shared objects AND multiple shared object (don’t ask me if you would need this feature…)
- Can tell if object has already created via the of_getusage counts
Helps minimize memory leakage - automatically destroys all valid objects upon destruction
How
To enable the object manager services:
To enable the help services - in the open/constructor event of the window, place "of_setobjectmanager(true)". This will create the object manager’s object, inv_factory in the gnv_app variable
How to create/use a globally shared object:
- u_employee lu_employee
- lu_employee = gnv_app.inv_factory.of_createglobal("u_employee")
- lu_employee.of_modifyssn("999-999-9999")
- gnv_app.inv_factory.of_destroy(lu_employee)
How to create/use a shared by name object:
- u_employee lu_employee
- lu_employee = gnv_app.inv_factory.of_createshared("u_employee","Joe Smith")
- lu_employee.of_modifyssn("999-999-9999")
- gnv_app.inv_factory.of_destroy(lu_employee)
Callable Functions
- nonvisualobject OF_CREATEGLOBAL(string classname): Create a globally shared instance of an object (no share name required)
- nonvisualobject OF_CREATESHARED(string classname, string sharename): Create a shared instance of the object with a sharename
- nonvisualobject OF_CREATEUNIQUE(string classname): Create a unique instance of the object.
- long OF_GETUSAGE(string classname): Get the current usage count for a globally shared object
- long OF_GETUSAGE(string classname, string sharename): Get the current usage count for a shared object
- OF_DESTROYOBJECT(nonvisualobject): Destroys (only if its usage count is 0) the passed object
- OF_SETGLOBALDESTROY(boolean): Sets whether to destroy a globally shared object when usage count falls to zero. "True" destroy it, "False" keep it active
Public Instance Variable
- IL_INVALIDIDX- internal error - array index was not valid
(can be returned from OF_GETUSAGE)
- IL_NOTFOUND- passed object could not be found
(can be returned from OF_DESTROYOBJECT or OF_GETUSAGE calls)
- IL_INVALIDOBJ- passed object is invalid
(can be returned from OF_DESTROYOBJECT)
| Download the | About the extension contributor |
| Revision History | ||
| 02/07/1998 | Initial Revision | Ver. 1.00 |
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