Mousehole Report

By Rusty Hodge & Larry Nedry, Mousehole BBS

From: Willcox

Re: Deleting a Folder

I am having trouble deleting a folder using the Low Level File Manager routines. I have created a folder and put some temporary files in it. At the end of my program, I would like to delete this directory. I am trying to use PBHDelete. I first delete all the files in this folder. Then, I try to close the working directory with PBCloseWD since I opened it with PBOpenWD. Then I call PBHDelete. I get error -47, fBsyErr, File is busy. I have tried various parameters in PBHDelete (WDid, vRefnum, name of folder), but I still get -47. Also, when I do this with MultiFinder turned off, I can not delete the folder from the Finder, it too says the folder is busy. Help.

From: Adept

Re: Deleting a Folder

When doing any PBOpen calls, you have to be sure to set your ioWDProcID to ‘ERIK’, the magic ‘longint’, otherwise it will be undeletable by the finder (until reboot), You might be calling PBClose with something != PBOpen and != to ‘ERIK’..

From: Mikec

Re: Setting current folder

Bryce, I am excited to see your message #878 that creates new folders. I have been wanting to do this for an application for a long time. But I am just starting to program and have little idea how to fit your listed code into a procedure that will create the folder. Can you help me by listing a more complete procedure or uploading a text file? I use LSP and would be delighted to hear from you.

From: Tony

Re: Setting current folder

Mike, Below is the list of a function call CreateFolder. I believe this will do what you want. It takes as parameter the name of the folder and the volume reference of where to put the folder. In return, it will pass back and errorcode and the FolderID. The folderId is in fact the Directory Id and can be used a vRefNum (volume reference no) in any of your File I/O calls.

Function CreateFolder(FolderName:str255; vRefNum : integer;
varFolderId:longint):OSErr;
Var
 Blk:HParamBlockRec;
 errorcode :OSErr;
begin
   with blk do
    begin
     ioCompletion := nil;
     ioNamePtr := @FolderName;
     ioVrefNum := vRefNum;
     ioDirId := 0;
   end;
  errorcode := PBDirCreate(@blk,false);
 FolderID := blk.ioDirId;
 CreateFolder := errorcode;
end;

Hope this helps.

From: Shaper

Re: List Manager problem...

Does anyone have any source code for the List Manager routines? I got the source to the LDEF’s in the Think Pascal library on CompuServe and tried to use that source but it’s kind of strange because he used custom LDEFs with variable column numbers. I want to use the LDEF that comes in the system file to make a list of people’s names, and I can get the list to appear but the only way to scroll it is to click on someone’s name and then drag downward to scroll down - the arrow buttons don’t work for some reason. Also, it doesn’t always hilite the cell that you click on, so you have to keep clicking on different parts of the list cntl until one does hilite before you can scroll up or down...

From: Jumpcut

Re: List Manager problem...

If you don’t specify a LDEF, the List Manager will use the standard system LDEF. You can then set the list’s selFlags to make sure things get selected properly. CHeck around page 270 of IMIV. I was having similar problems after I changed the font and style of the window the list was in. First thing to check - make sure your window is a noGrowDocProc, or else the grow box (whether you draw one or not) will keep mouseDown events from scrolling the list down. I’m sure you’re using LClick, so I won’t bother to mention that. My only other suggestion is to avoid the obviously stupid (unlike me) and remember to change the font & face before creating the list.

From: Inbox

Re: Endless lists

I’m doing a numerical analysis of a chaos/pattern generation problem, but I’ve been temporarily delayed by the need of array-like structures with their original size unknown. Beginner C skills decrease my programming self-confidence, so I would like to hear you comments on the topic of lists... I did the following:

  typedef struct mystruct{
            int myint;
            mystructptr nextstruct;
            } *mystructptr;

But, I cannot do that because *mystructptr isn’t yet recognized by the compiler. Should I make nextstruct a ptr and then coerce it when creating a new structure? If not, what are your suggestions?

Thanks for listening, _inBox_

P.S. Is there any C trick for making self-referencing things like this one

(I mean a language directive of some kind...)

From: Siegel

Re: Endless lists

For a self-referential structure (say, a linked list): .

typedef struct element {
  int field1;
  long field2;
  struct element *next;
} element, *elementPtr;

Since this is the Mac, why not use a handle-based structure to support an array of dynamic size? As in:

typedef int *PInt, **HInt;
.
{
 Hint myIntHandle = NewHandle(0);
.
 /* sorry for the caps slipup above */
 SetHandleSize(myIntHandle, (long)nIntegers * sizeof(int));
 (*myIntHandle)[nIntegers - 1] = someValue; /* assign the last element 
*/
}

From: Inbox

Re: Endless lists

Thanks a lot. And just when I thought that I was out of the woods....

AAARGGGHHHH !!!!! The Mac’s random number generator turns out to be unusable by any self-respecting chaosologist for any purpose. I used statistical analysis to determine its bias, and then compared it to tables of acceptable fluctuations. And guess what, it SUCKS!!! (pardon the language)... So I set out to write a random number generator. Done. And, here comes the big one: how can I raise small integers to humongous powers??!! For example, 5^10000 will definitely cause an overflow for C’s “pow” function. The max number that can be stored in a 64 bit variable is 1.84467E19. But, 5^10000 or something similar just blew me out of the water.

Any suggestions are very very welcome. (and needed....).........

From: Apage

Re: Endless lists

If you’re using a Mac II the 881 uses the extended precision format to 80 bits. If you have a mac with an 882 (which can be dropped in with no trouble and few tools), the precision goes out to 96 bits.

From: Inbox

Re: Endless lists

Ah, but are you talking about the mantissa or the whole number? For example, my HP 28S (calculator) has a 12-digit mantissa and allows powers up to 500. With the 96 bit format the max is 28. Maybe the calculator scheme holds for the Mac?! Then only the mantissa is limited by the bits of a format. Take Matematica, for example... It can do number crunching with infinite precision and allows mega-powers. I guess it uses its own package but....

From: Tron

Re: Receiving events from a DA

Does anyone know how to receive events from a DA that is written in LSC? In IM #1, page 446, it says that the control routine receives in the csParam field a pointer to an event record. Hence:

     case 2:   /*  control  */
        switch (p->csCode) {
           case accEvent
               DoEvent((EventRecord *)p->csParam);
               break;
        }

I figured that this would work, yet I cannot handle any events in my DoEvent routine. Anyone ever dealt with DA’s from LSC before?

From: Macguru

Re: Receiving events from a DA

Have you set up your DA’s Event mask to tell it what events you are expecting to receive? This is done in the header.