Program Structure

In this chapter we will learn about using many source code files in the same project.

Source Code File Sections

Each source code file may contains the next sections (in the same order).

Source Code File Sections
Include Files
Statements and Global Variables
Functions
Packages and Classes

The application maybe one or more of files.

Using Many Source Code Files

To include another source file in the project, just use the include command.

Syntax:

include  "filename.dgn"

Note

The Include command is executed directly by the compiler in the parsing stage

Tip

if you don’t know the file name until the runtime, or you need to use functions to get the file path, just use eval().

Example:

# File : Start.dgn

include "sub.dgn"

sayhello("World")

# File : sub.dgn

func sayhello(cText){
        showln "Hello " + cText 
}

Include Package

Using the ‘include’ command we can use many dgn source files in the same project

But all of these files will share the same global scope

We have also the “include package” command

Using “include package” we can include a library (*.dgn file) in new global scope

This is very useful to create libraries that avoid conflicts in global variables

Example:

File: includepackage.dgn

x = 100
showln "Hello, World!"
include package "testincludepackage.dgn"

showln x
test()

File: testincludepackage.dgn

showln "Hello from testincludepackage.dgn"

x = 1000

test()

func test()
        showln x
end

Output:

Hello, World!
Hello from testloadpackage.dgn
1000
100
1000

Include Again

Using this command we can include the Dragon native source file which contains constants more than one time.

This is useful when using Dragon native source files for translations through global constants.

Example:

Loading the same file again using the (Load) command is not possible

Because the (Load) command load the same source file only for the first time and ignore next times.

So we have to use the (Load Again) command.

Where we can use these files again during the runtime as in the next code

func setLang( nLanguage){
        if C_ENV_DEFAULT_LANG == nLanguage
                return
        end
        C_ENV_DEFAULT_LANG = nLanguage
        # Change the language
                match nLanguage
                        case C_TRANSLATION_ENGLISH
                                include again "translation/english.dgn"
                        case C_TRANSLATION_ARABIC
                                include again "translation/arabic.dgn"
                end
}