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Creating Applications in C++Builder
Inherit
The Inherit method of usage is similar to Copy, but with one important distinction: The new
object is still tied to the base object. If you modify the base object, the newly created object
will be updated to reflect the changes made to the base object. The inverse is not true,
however. You can modify the new object without it having any effect on the base object.
To illustrate this type of object usage, consider the following scenario: Frequently, information
managers will create a spreadsheet in a spreadsheet program and use the contents of that
spreadsheet in a word processing program in order to present a report. They will usually opt
to link the data to the spreadsheet when pasting from the Clipboard or importing the
spreadsheet into the word processor. That way, when changes are made to the spreadsheet,
the word processing document is automatically updated to reflect the new data. In the same
way, changes made to a base form will automatically be reflected in all forms inherited from
the base form. Use the Inherit option when you want to have several forms based on a
common form that might change at some point. Any changes in the base form will be
reflected in all inherited forms.
Use
The Use option is not common. When you use an object, you are opening that object directly
for editing. Use this option when you have saved an object in the Repository and you want
to make permanent changes to that object. In the section “Inherit” I said that changes made
to a base form would be reflected in all inherited forms. If you wanted to make changes to
a base form, you would open it in the Object Repository with the Use option.
Now What?
Exactly what takes place when you select an object from the Object Repository depends on
several factors. The factors include the type of object selected, whether a project is currently
open, and the usage type you have selected (Copy, Inherit, or Use). If you have an application
open and you choose to create a new application from the Object Repository, you will be
prompted to save the current project (if necessary) before the new project is displayed.
TIP
Choosing File | New Application from the main menu is a shortcut for
starting a new application. It is equivalent to choosing New from the
main menu and then choosing the Application object from the Object
Repository. Similarly, the New Form, New Data Module, and New
Unit items on the main menu are shortcuts for their equivalents in the
Object Repository.
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