What Is Declaration?
Declaration is the means by which data, functionality, and information in a program are identified. Although most programmers think of variables when the word "declaration" is bantered around, declaration covers a wider range of programming tasks, one of which is variable definition.
Declaration has a larger impact on the end user's experience than does style or commenting (which are discussed in Chapter 3, Commenting and Style), so an added amount of care needs to be placed on its usage. Although the use or avoidance of a consistent naming system may have no effect on the final compiled product, many other aspects of declaration can dramatically affect the speed, robustness, and correctness of your Visual Basic application.
Not every programming language requires the use of variables for data storage. Consider LISP, one of the more common non-procedural languages. Although variables are available in LISP, you have to neither use them nor declare them to have a working program, even a somewhat complex program. Yet even LISP has some forms of declaration. How much more, then, does Visual Basic have, with its abundance of data and procedure types.
Among the forms of declaration discussed in this chapter are the following.
Local, module, and global variable names and data types
Public and private subroutine, function, and property names
Parameter names and data types, and function return values
Line labels
Control names
Database object references
Declare statements
Intrinsic constants and values accessed through type libraries
User-defined data type tags and elements
Enumerated data types
Programmer-defined constants
Class names and members
Custom control properties and elements
Form, module, custom control, property page (etc.) definitions
Order of major routine components
And you thought we were just going to talk about variables.