To write AHK plugin you must have basic knowledge of AutoHotKey programming language. If you never used it, check out AHK quick start tutorial.

I will start from most trivial sample – plugin that returns the file size. Lets name this plugin Size

In \plugins folder there is ahk plugin template, file myplugin. You can use this file as a base for new MRS plugin. If you change extension of template file to .ahk and reload MRS you can see that it immediately works if you click the Plugins button. For the start go to \plugins folder, and rename MyPlugin file to Size.ahk and open it in editor.

Now use search & replace of your editor to construct valid subroutine names:

Search:  MyPlugin
Replace: Size

The preparation is done, now you must implement Size subroutine. In the header of the file there is a list of global variables that MRS will fill before calling plugin’s main subroutine. For instance, #fn will contain file name, #fd file’s directory, etc. Subroutine must return result into the variable #Res.

As we need file size, we need full file path, sent by MRS in #fp variable. This is the complete plugin implementation:

Size:
	FileGetSize, #Res, %#fp%, K
return

FileGetSize is AutoHotKey function to get the file size. Above, we are saving file size in kilobytes into #Res variable and return control to MRS.
Now, save this file and restart MRS. “Size” should be in the list of the plugins. Type [=Size] mask to verify that it works correctly.

This is pretty much everything that you need to know about AHK plugin: implement routine by the same name as plugin and return the data into the #Res variable. There are some other things, but they are not mandatory.

Let me now extend this plugin so it can return file size in 3 formats: MB, KB and B. This is where you implement other subroutine which only purpose is to return the fields of the plugin separated by new line char (`n):

Size_GetFields:
	#Res = MB`nKB`nB
return

Now user will be able to type [=Size.MB] or [=Size.KB] to get appropriate format or again just [=Size] to stick with default format. This is also used to check parsing mask for errors by MRS, so [=Size.GB] will be reported as error as GB is not in the field list.

Main plugin subroutine must now be changed to return data according to the requested field. MRS sends field to the plugin in #1 global variable. The complete code for new plugin is:

Size:
   FileGetSize, #Res, %#fp%		;get the file size in bytes
   if #1=MB
	#Res /= 1048576.0
   else if #1=KB
	#Res /= 1024.0
 
   If #tmp := InStr(#Res, ".")		;use 2 decimal digits
	#Res := SubStr(#Res, 1, #tmp+2)
return
 
Size_GetFields:
   #Res = MB`nKB`nB
return

You can test plugin fields by typing them or by clicking Size in Plugins menu which will bring the menu with available fields.

Finally, lets check more complex example. To continue with file information, lets return size, version and attributes. Lets create new plugin that will serve all that data and call it File. Do the same thing as before to create File.ahk and its subroutines. In File_GetFields, we will return string containing all fields we serve while Size field will also have 3 units:

File_GetFields:
	#Res = 
	(Ltrim
	    Size|M|K|B
	    Version
	    Attributes
	)
return

You specify units near the filed name by using | after the field name as separator. The above code is the same as writting 

#Res = Size|M|K|B`nVersion`nAttributes

just more clear to read.

MRS returns field in #1 and unit in #2 so you can get the job done like this:

File:
	If (#1 = "Attributes") {
		FileGetAttrib, #Res, %#fp%
	} 
	else if (#1 = "Version") {
		FileGetVersion #Res, %#fp%
	else { 
		FileGetSize, #Res, %#fp%		;get the file size in KB
		if #2=MB			
			#Res /= 1048576
		else if #2=KB
			#Res /= 1024
		If #tmp := InStr(#Res, ".")		;use 2 decimal digits
			#Res := SubStr(#Res, 1, #tmp+2)
	 }
return

Remarks