Re: Finder Extensions

[jmk3@crux3.cit.cornell.edu (Jay Krell)]

>From: FORDE@UV6.EGLIN.AF.MIL
>Subject: Finder Extensions
 
>>Finder Extensions are INITS.  If you want them available all the time (not
>>just while in the Finder), put them in your System.Setup folder.
 
>How are Finder Extensions accessed, if installed in this manner?  Do they
>show up in the menu bar of other desktop programs?
 
>However, to get the Finder "Extras" to show up I had to move the folder
>onto the harddrive and in the same directory as the Finder.  If I left it
>in my system.setup folder on the ROMDisk the "Extras" item never appeared.
 
I'll answer the easy question first, that of where the files go.
 
It sounds like you are putting the FinderExtras folder in the System.Setup
folder. This is wrong. FinderExtras goes in the System folder "along side of".
Perhaps Finder should recurse down folders, but it doesn't.
 
As for putting extensions in System.Setup and using them from other programs:
 
The Finder communicates with extensions through a set of request codes (System
6's inter-process application includes a call SendRequest; it is used to do the
communication.) These requests are of the form finderSaysXXX (Finder sends
these out) and tellFinderXXX and askFinderXXX (sent to Finder). For the most
part, these are very Finder dependent. However, there exist two codes,
finderSaysBeforeCopy and finderSaysOpenFailed, that can be used (Apple-approved
and Apple-suggested) outside of Finder. If you double-click a file and Finder
finds no application to open it, finderSaysOpenFailed is sent along with the
file's pathname, and anything that receives it is free to deal with the file.
If something "accepts" the request, Finder does not put up the dialog "Could
not find application...".
 
Examples: IR opens NDA's, CDA's, inits, Finder extras (they have their own
type), and GS/OS drivers. ControlPanel opens control panels. EgoEd opens
textual files, include text, AppleWorks WP, source, and Teach. EasyMount opens
its documents. There are various extensions to deal with sound and graphics
files.
 
If you put IR in the FinderExtras folder, you can only successfully double
click its types in Finder. If you put it in System.Setup, those files can be
opened outside of Finder.
 
So, where to finderSaysBeforeOpen and finderSaysOpenFailed come from outside of
Finder? (plug approaching) I wrote a small NDA called OpenAny that lets you
select any file with a standard open file dialog and then sends out the request
codes. Such an NDA was actually suggested by Apple in the System 6 Ref. OpenAny
is freeware. I believe someone else wrote something similar and made it
shareware.
 
Caveat: I don't think IR opens Finder extensions from other applications. This
makes sense. Also, opening files with IR _can_ be dangerous since those
programs expect a boot environment, not a desktop environment.
 
  --Jay, jay.krell@cornell.edu