External language: Programming in C#

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Managing external languages

CSharp

External language: Programming in C#

Overview

Implementation

Loading the WINDEV library (WDL)

Running WINDEV codes from the external language

Ending the application

See also

External language: Programming in C#

Overview

We are going to call the elements developed in WINDEV (project, windows, analysis, ...) from the C# language.

Reminder: C# is a language of the .NET platform.

The WLanguage code used from the external language will be dynamically compiled and run during its call.

This mode is illustrated by the City.cs project (in C# format) included in the "ExternalLanguages\C#" subdirectory of the WINDEV setup directory.

Remarks:

C# does not allow you to use the HFSQL engine. To handle the HFSQL engine, perform the necessary processes in WINDEV.
Compatible with Visual C++ versions 4.2 and 6.0 and later.

Implementation

Including the files of the C# interface of WINDEV

The following file must be found in the runtime directory of your C# program in order to call the C# interface of WINDEV:

WINDEV.CS
wdxxxle.dll
wdXXXICS.DLL

The methods of the WINDEV class must be called and prefixed by "WinDev.":

WINDEV.CALLWD("LIBRA,Disk,city.wdl");

Loading the WINDEV library (WDL)

The WINDEV library (.WDL) contains all the project elements (windows, reports, classes, queries, analysis, ...). Therefore, it must be loaded in memory in order for its components to be called.

Caution: If windows must be loaded outside the library, the code of each one of these windows must be included in the corresponding ".WDW" file ("Include the compiled code" must be checked in the "Details" tab of the description of each window).

// Opening the library
// if WDInt is not null, the library was not found!
WINDEV.CALLWD("LIBRA,Disk,city.wdl");
if (WINDEV.WDInt() == 0)
{
...
}
else
{
// Library not found
WINDEV.CALLWD("Error, Library not found");
}
// Terminate...
WINDEV.WDEnd();

Running WINDEV codes from the external language

1. Calling a WLanguage code

All the WLanguage functions can be called from the external language. The behavior of these WLanguage functions as well as the returned values are identical whether they are called:

from WINDEV or
from the interface of external language

To find out the parameters and the return values of a WLanguage function, see the online help or the documentation about WLanguage.

The call to a WLanguage procedure from the external interface is performed by CALLWD. For example:

// Open the first window of the program that contains the menu
WINDEV.CALLWD("OPEN,menufc.wdw");

2. Retrieving the events triggered in the WINDEV windows

The input in the WINDEV windows requires to retrieve the events triggered in these windows.

To retrieve the user events (click on a menu, on a button, and so on), you must implement a system based on a loop in your C# program. This loop will remain active as long as the WINDEV window is opened and it will be used to intercept each user action.

To find out the type of action performed by the user, you have the ability to use a character string variable (in WLanguage) named 'WDKey'. This variable will be used in your WLanguage code to signal to the C# program the button that was pressed for example.

Example: C# code

// Open the first window of the program that contains the menu
WINDEV.CALLWD("OPEN,menufc.wdw");
// the program loops until the File Exit option
// is selected
while (bInput)
{
// perform the input of the menu
WINDEV.CALLWD("Screen,Input");
// the status report WDKey is set to *M* when a menu choice
//was selected
string szOption = WINDEV.WDKey();
if (szOption = "*M*")
{
...
}
}
WINDEV.APPELWD("FERME");

Code for intercepting the selection of "File..Exit" of the WINDEV "Menu" window:

// cancelation
if (WINDEV.WDKey() == "FE")
{
bInput = false;
}

When the user selects "File..Exit":

WDKey will return "*M*".
WDString will return the shortcut letters in the order in which the menus are selected. In our example, WDString returns "FE".

Ending the application

To end the use of external interface, type the following code lines:

// Terminate...
WINDEV.WDEnd();