Macro Scheduler has a number of scheduling features to allow you to specify when a macro should fire. One of these mechanisms is called a Trigger. There are several trigger types:

• Window Event
• File Event
• Folder Event
• Custom Event

A Window Event can be set to fire when a specified window appears or disappears. Similarly file events can be set to fire the macro when the specified file exists or ceases to exist. Folder events offer much the same (a folder exists or ceases to exist) but also a little more. A Folder event can also be configured which will fire the macro when a new file appears in the folder, or a file is removed from the folder.

New File Triggers

With a “New File in Folder” trigger the macro will fire whenever a new file appears in the folder, regardless of what that file is called. This can be very useful and is often used to detect incoming files for further processing. In a situation like this we would need to detect that a new file has appeared and then do something with it. Using the New File in Folder trigger will cause the macro to run, but then we need the macro to determine what that file is called. We can do that with a VBScript function which returns the newest file in a folder:

VBSTART
Function NewestFile(Folder)
Set oFSO = CreateObject("Scripting.FileSystemObject")
Set oFolder = oFSO.GetFolder(Folder)
dPrevDate = "0"
For Each oFile In oFolder.Files
  If DateDiff("s", dPrevDate, oFile.DateLastModified) > 0 Then
    sNewestFile = oFile.Path
    dPrevDate = oFile.DateLastModified
  End If
Next
NewestFile = sNewestFile
End Function
VBEND

We can then call it like this:

VBEval>NewestFile("c:\downloads"),filename

This will return in filename the path of the newest file in the given folder. So if our macro is fired by a new file appearing in a folder it can then run this code to get that file’s path and do something with it.

Custom Triggers

Custom triggers allow you to create any kind of trigger you can think of by executing Macro Scheduler code. Maybe you want to monitor the contents of a text file or an INI file entry, a registry entry or the size of a specific file. If you can code the check in Macro Scheduler you can create a trigger out of it.

Custom triggers work by linking to a script (.scp) file which contain two subroutines. One subroutine is called Trigger and the other Reset. Initially the Trigger subroutine is called repeatedly until it sets MACRO_RESULT to TRUE. Thereupon Macro Scheduler calls the Reset routine instead until it too sets MACRO_RESULT to TRUE and the cycle then continues.

By way of an example lets say we want to trigger a macro based on the value of an INI file entry. Let’s say our INI file looks like this:

[MyStuff]
Color=red

Let’s say we want to trigger a macro to run when the Color entry in the INI file gets set to “blue”. Here’s our trigger script:

SRT>Trigger
  ReadIniFile>d:\files\myini.ini,MyStuff,Color,gColor
  If>gColor=blue
    Let>MACRO_RESULT=TRUE
  Endif
END>Trigger

SRT>Reset
  ReadIniFile>d:\files\myini.ini,MyStuff,Color,gColor
  If>gColor<>blue
    Let>MACRO_RESULT=TRUE
  Endif
END>Reset

So here the Trigger routine which is executed continually by the scheduler will return TRUE only if Color in the INI file becomes equal to “blue”. Thereupon the Reset routine will be executed which will reset the trigger when Color is no longer “blue”. After that the Trigger routine is executed again.

Since Trigger routines are run frequently on a very tight interval they should be kept as small as possible and should not be long running. Don’t make Trigger scripts that perform too much complicated processing or include delays as this could cause resource issues. Sometimes, for more complicated “triggers” or monitoring scripts you may be better off creating a looping macro or repeating macro. E.g. if you wanted to poll a POP3 server for an email message containing specific content this is a more time consuming process subject to network delays so would probably not be a good candidate for a Custom Trigger. Instead create a macro which checks the email every few minutes, or one that loops continuously.