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From: Jim.Spencer@p510.f22.n282.z1.mn.org (Jim Spencer)
Newsgroups: comp.sys.mac.hypercard
Subject: HC 2.0, XCMDs, THINK C, globals
Message-ID: <672472805.1@mmug.mn.org>
Date: 24 Apr 91 02:15:40 GMT
Sender: UUCP@p0.f22.n282.z1.mn.org
Lines: 19


Brad Pickering writes in a message to All

BP> I have some questions about how HC 2 handles XCMDs. I would like 
BP> to write XCMDs that remember their globals between calls. I tried 
BP> this with a simple XFCN that just added 1 to a global and returned 
BP> the value as the result. Each time it was called it came back 
BP> with the next higher number. But I tried to do this with a more 
BP> complex XCMD and I've be having lots of problems. Does HyperCard 
BP> jump to the beginning of the real resource or does it make a 
BP> copy and jump to the beginning of the copy? If it is using the 
BP> real resource does it honor the purgable and locked attributes 
BP> of the resource? I tried marking the resource as locked and it 
BP> seemed to crash HyperCard. If I use global variables which are 
BP> pointers to code or data within the XCMD don't want HyperCard 
BP> to move my resource around makeing the pointers invalid. 

HyperCard makes a copy of the external and then jumps to the beginning of it.  The solution to your problem is to create globals in your script and pass the values to the external (or read them in the external).  You should note that externals don't have globals per se.  There are mechanisms to in effect create these globals but they are not values off of HyperCard's A5 global space.