DISK I/O

Here is some FBII-code I adopted following the recommendations of Apple-IM.

Please note that FINDFOLDER(...) works for all volumes, not only for the system volume!

' --  FileSystSpecification record (IM/Files/2-86):
DIM RECORD fsSpec
    DIM fsVRefNum%
    DIM fsParID&
    DIM 63 fsName$
DIM END RECORD .fsSize
' --  70 bytes

' FSS record of temporary file:
DIM tmp.fsSize

'**********************************************************
LOCAL MODE
' (IM/Files/2-166)
LOCAL FN FSMakeFSSpec(vRefNum%,dirID&,@fileName&,specPtr&)
    '
    `     clr.w   -(sp)                             ; room for result:
    osErr%
    `     move.w  ^vRefNum%,-(sp)   ; volume reference number
    `     move.l  ^dirID&,-(sp)             ; (parent) directory ID (of
    FILE)
    `     move.l  ^fileName&,-(sp)       ; Ptr to file or pathname
    `     move.l  ^specPtr&,-(sp)         ; Ptr to FileSystemSpecification
    RECORD
    `     dc.w    $7001,$AA52             ; selector, A-trap
    `     move.w  (sp)+,D0                  ; D0 := osErr%
    `     ext.l   D0                                 ; make long integer (FB
    convention)
END FN
' result codes 0,-35,-43
'***********************************************************
'Code Snippet:

'(1) Give a unique name to the temporary file:

' file name longer than maximum?
LONG IF LEN(origName$)>26
    ' calculate ellipsis:
    origName$ = LEFT$(origName$,13)+" --- "+RIGHT$(origName$,12)
END IF
' temporary file name:
tmpName$ = origName$ + ".temp"

'(2) Find temp-folder on your file's volume with vRefNum%
'or create it if necessary (details: IM/Files/1-25):

err%=FN FINDFOLDER(vRefNum%,_"temp",_kCreateFolder,tmpVRefNum%,tmpParID&)
' FSS of temp-file:
IF err%=_noErr THEN err%=FN FSMakeFSSpec(tmpVRefNum%,tmpParID&,tmpName$,@tmp)
' fnfErr: file must be created:
LONG IF err%=_noErr OR err%=_fnfErr
    ' reset error:
    err% = _noErr
    ' create temp-file:
    err% = FN FSpCreate(tmp,_"trsh",_"trsh",_smSystemScript)
END IF

'If this code snippet does not work reliable,
'try _pTrue instead of _kCreateFolder.
'Do not forget to delete the temporary file when your finished!
'***********************************************************

I intensively use the above code without any problems.

   osErr% = FN FINDFOLDER (_kOnSystemDisk,_KtemporaryFolderType,0, prefVRefNum%, prefDirID&)

Wait a minute. You are specifying 0 for the createFolder parameter. That equates to false - meaning, "Don't create the folder I am looking for if it doesn't exist". If you want to always find the folder, you should be using _true (or non-zero) for that parameter.

David (the other one) was mostly right. I had tried the above line with the createFolder set to _kcreateFolder (which the constant tool says equates to 1) and it made no difference. However, if you set the createFolder parameter to _zTrue (-1) then the above call always works. It appears that there is some problem here. IM says the createFolder parameter should be set to true, to create a folder if one does not exist.

http://developer.apple.com/techpubs/macos8/Files/FolderManager/FolderMgrRef/frameset.html

All that matters however, is that if you want be be certain that a temp folder will be found - set createFolder to _zTrue not _true or _kcreatefolder

PS These OS 8 documents indicate some really neat stuff is now possible with FINDFOLDER and related calls.

The problem is that different development environments or languages evaluate their true constant differently. FutureBasic evauates _true to 1 (I believe), whereas Pascal and C evaluate true to -1. _ztrue in FB II is -1, which is why it works.

Good catch, David! =) Glad you got it figured out.

This is not quite right - from IM and a LOT of testing, it appears that with OS 8.5.1 there is not necessarilly a Temporary Items folder straight after start-up. If you search for one with say DiskTools (thanks Tedd) you wont always find one - this is why FINDFOLDER when it is set to "dont create a folder if you dont have one" might return an error -43.

It is true that you should not delete the folder in your app, and everything else Mark said is correct. Thus if any application creates a Temporary items folder, it will be available to all other apps, you however cannot assume that one has been created when your app starts. I suspect this behaviour has only recently changed, and it is possible that some extensions and/or previous systems do create the folder at start-up (or never remove it).

The problem is the old Pascal true = -1 Basic true = 1. The constant _kcreateFolder defined in FB is incorrect, use _zTrue instead, and you can happily use this feature. FINDFOLDER should not not create a folder if one exists (though I think in my testing I created a phantom system folder - which was very bad news). You will run into problems, as Mark suggests, if you try to create the folder by any means other than a call to FINDFOLDER.