Extern (Reserved word)

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Including constants
Deploying the application

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List of reserved words

Extern (Reserved word)

In french: Externe

EXTERN is used to:

Include a text file containing WLanguage commands in an application (see syntax 1). This feature is only available in the initialization code of the project, in the declaration code of the global variables of a window/page and in the declaration code of a class.
Declare an external object (see syntax 2).

Example

// Syntax 1
// Include the "WinConst.wl" file that contains the standard Windows constants
EXTERN "WinConst.wl"

// Syntax 2
EXTERN ExampleWindow
LoadWDL("User1.WDL")
Open(ExampleWindow)

Syntax

Including a text file in an application Hide the details

EXTERN <File name>

<File name>: Character string

Name of text file containing the WLanguage code that must be included in an application. This is a standard text file, created by any text editor.
A complete path can be specified (for example: "C:\WDProjet\MesConst.wl").. If the path is not specified, the file will be sought:
in the project directory,
in the "\Personal\External" subdirectory of the WINDEV, WEBDEV and WINDEV Mobile installation directory.
Including a text file with EXTERN has the same effect than copying a text file in the code editor.

Declaring an external object Hide the details

EXTERN <Name of External Object>

<Name of external object>: Character string

Name of external object (variable, constant, ...) to declare.
EXTERN is used to declare a variable that will exist only when running the application.
For example, the EXTERN keyword can be used to handle a window found in an external library (loaded by LoadWDL).

Remarks

Including constants

Including files is very useful to describe the constants common to several projects or used by the operating system. Use EXTERN to include in the code a file containing the common constants.
Including files can only be performed in the following processes:
- Initialization code of project,
- Declaration code of global variables of window or page,
- Declaration code of class.
Several files defining the constants are supplied (in the "\Personal\Extern" subdirectory of WINDEV, WEBDEV or WINDEV Mobile):
- "WinConst.wl": Standard Windows constants.
- "Limites.wl": Constants corresponding to the limits of WINDEV, WEBDEV and WINDEV Mobile data types.
- "ListDefinitionHF.wl"HFSQL constants used for logging (see Files handled by the log process).
- "Except.wl ": Constants used for exception handling.
- "KeyConst.wl ": Standard Windows constants used for keyboard keys. These constants can be used with KeyPressed in the optional WINDEV processes ("Key down" or "Key up") by using the _EVE.wParam variable.

Deploying the application

When installing the application on the client computer:

If the file path is specified: The file must be installed in the specified directory.
If the file path is not specified: By default, the file will be automatically installed in the project directory.