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Help / WLanguage / WLanguage functions / Standard functions / External file functions
  • Special cases
  • WLanguage procedure
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Stored procedures
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
// Name of the file to watch
sFileName is string = "C:\Temp\MyDir\MyFile.extension"
// The ProcessModification procedure will be called when the 
// "C:\Temp\MyDir\MyFile.extension" file is modified.
IF fWatchFile(sFileName, fWatchFile_Callback, ...
		fwCreateFile + fwModifyFile + fwDeleteFile +  ...
		fwRename) THEN
	// Notifies the user that the file will be watched
	Info("The " + sFileName + " file will be watched.")
ELSE
	// Notifies the user that the file will not be watched
	Info("The " + sFileName + " file will not be watched.")
END

// Code of the procedure
INTERNAL PROCEDURE fWatchFile_Callback(sFullName, sFileName, nAction, sOldFileName)
	sActionDesignation is string
	// The designation of the action depends on nAction
	SWITCH nAction
		CASE fwCreateFile: sActionDesignation = "Creating files"
		CASE fwDeleteFile: sActionDesignation = "Deleting files"
		CASE fwModifyFile: sActionDesignation = "Modifying files"
		CASE fwRename: sActionDesignation = "Renaming files"
	END
	// Add a line containing the information about the modification 
	// in the TABLE_MODIFICATIONS control
	TableAddLine(TABLE_MODIFICATIONS, sFullName, sFileName, ...
		sActionDesignation, sOldFileName)
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:
fwAllAll actions are watched. Corresponds to fwCreateFile + fwModifyFile + fwRename + fwDeleteFile.
New in version 2024
Before version 29 Update 2, this constant was named ftAll.
fwCreateFileCreation of <File to watch>.
New in version 2024
Before version 29 Update 2, this constant was named ftCreateFile.
fwDeleteFileDeletion of <File to watch>.
New in version 2024
Before version 29 Update 2, this constant was named ftDeleteFile.
fwModifyFileModification of <File to watch>.
New in version 2024
Before version 29 Update 2, this constant was named ftModifyFile.
fwRenameRenaming of <File to watch>.
New in version 2024
Before version 29 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.
Caution: The following processes cannot be run 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: wd290std.dll
Minimum version required
  • Version 18
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Last update: 03/29/2024

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