fWatchFile (Function)

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Help / WLanguage / WLanguage functions / Standard functions / External file functions

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fWatchFile (Function)

In french: fSurveilleFichier

Warning
From version 2024, fTrackFile is kept for backward compatibility. This function has been replaced with fWatchFile.

Starts watching a file. In case of file modification, a specific procedure is run in a thread.

Example

// Nom du fichier à surveiller
sNomFichier is string = "C:\Temp\MonRep\MonFichier.extension"
// La procédure TraiteModification sera appelée lorsque le fichier 
// "C:\Temp\MonRep\MonFichier.extension" sera modifié.
IF fWatchFile(sNomFichier, fSurveilleFichier_Callback, ...
		fwCreateFile + fwModifyFile + fwDeleteFile + ...
		fwRename) THEN
	// On informe l'utilisateur de la mise sous surveillance du fichier
	Info("La mise sous surveillance du fichier " + sNomFichier + " a réussi.")
ELSE
	// On informe l'utilisateur de l'échec de la mise sous surveillance du fichier
	Info("La mise sous surveillance du fichier " + sNomFichier + " a échoué.")
END

// Code de la procédure interne
INTERNAL PROCEDURE fSurveilleFichier_Callback(sNomComplet, sNomFichierSurveille, nAction, sAncienNomFichier)
	sDesignationAction is string
	// La désignation de l'action subie dépend de nAction
	SWITCH nAction
		CASE fwCreateFile: sDesignationAction = "Création de fichier"
		CASE fwDeleteFile: sDesignationAction = "Suppression de fichier"
		CASE fwModifyFile: sDesignationAction = "Modification de fichier"
		CASE fwRename: sDesignationAction = "Renommage de fichier"
	END
	// Ajout d'une ligne contenant les informations de la modification 
	// dans le champ Table TABLE_MODIFICATIONS
	TableAddLine(TABLE_MODIFICATIONS, sNomComplet, sNomFichierSurveille, ...
		sDesignationAction, sAncienNomFichier)
END

Syntax

<Result> = fWatchFile(<File to watch> , <WLanguage procedure> [, <Changes to notify>])

<Result>: Boolean

True if file watching is enabled,
False otherwise. To get more details on the error, use ErrorInfo.

<File to watch>: Character string

Full name of the file to be watched.

<WLanguage procedure>: Procedure name

Name of the WLanguage procedure ("callback") called when a change is made to the specified file.
For more details on this procedure, see Parameters of the procedure used by fWatchFile.

<Changes to notify>: Optional Integer constant (or combination of constants)

Changes made to the watched file and for which the procedure is to be executed:
fwAll All actions are watched. Corresponds to fwCreateFile + fwModifyFile + fwRename + fwDeleteFile.
Before version 2024 Update 2, this constant was named ftAll.
fwCreateFile Creation of <File to watch>.
Before version 2024 Update 2, this constant was named ftCreateFile.
fwDeleteFile Deletion of <File to watch>.
Before version 2024 Update 2, this constant was named ftDeleteFile.
fwModifyFile Modification of <File to watch>.
Before version 2024 Update 2, this constant was named ftModifyFile.
fwRename Renaming of <File to watch>.
Before version 2024 Update 2, this constant was named ftRename.

Remarks

Special cases

To stop watching the file, use fWatchStop and fWatchStopAll.
To watch changes made to the contents of a directory, use fWatchDirectory.
Limitations:
- Only 5 files can be watched at the same time.
- It is not possible to watch a file located at the root of a disk (for performance reasons).

WLanguage procedure

The WLanguage procedure is run in a WLanguage thread.
Please note: the following processes cannot be executed in threads:

opening windows with WLanguage functions such as Open, Use, Close, etc. A specific management mode must be implemented if some windows must be handled in threads (rare case). For more details, see Opening a window in a secondary thread.
managing events.
managing timers.

For more details on threads, see Managing threads.

Component: wd300std.dll