Singularity is an extension to Black Hole. Singularity lets you partly integrate Black Hole's wastebin functions with the RISC OS Filer's functions. If you have Black Hole running, then there are two ways you can delete a file:
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1) You can drag the icon for the file from the directory viewer to the Black Hole icon. The file will be deleted subject to Black Hole's options. The wastebin part of Black Hole will keep a copy of the file if you have configured it to do so.
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2) You can click the MENU button over the file's icon and select 'Delete' from the Filer menu which appears. This will delete the file but Black Hole will not know about this and so the wastebin part of Black Hole will not be able to keep a copy.
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This is where Singularity comes in. Singularity (if you enable it) will trap all those occasions on which you delete a file by method 2 above and willkeep a copy in the Bin Directory.
{subhead}Configuring Singularity
Singularity is configured via the Black Hole Configuration window.
[1]
To turn Singularity on, select the 'Trap Filer Deletes' option. If you want to ignore Singularity, make sure the options
'Trap Filer Deletes'
'Report'
'Show Sprite'
are OFF.
I shan't explain the other options as they would probably make your head hurt.
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The options you use are now described.
Singularity is OFF by default. You can turn it on in a number of ways, but one to note is the clicking ADJUST (the right mouse button) over the Black Hole icon will toggle Singularity between ON and OFF. A small window will also open for a short time to inform you that you have just done something.
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To turn Singularity on from the configuration window, select the 'Trap Filer Deletes' option. The other options do the following:
{subsub}Show Sprite
will put an icon on the iconbar which will show if Singularity is currently on or off. Clicking on the icon will toggle between the two. The Singularity icon has a menu. The 'Remove' option on this menu will remove the singularity icon from the iconbar but will NOT turn it off if it is on.
{subsub}Remove at exit
should be left on.
{subsub}Report
will make a small window open every time Singularity traps a deletion. The window will close after a few seconds.
{subsub}Ignore ADFS floppy discs
If this is ON, Singularity will not be applied to deletions from floppy discs. This is usually a good idea.
The bit about File Systems to Ignore can be ignored.
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For Black Hole, the Singularity aspect is controlled by the module 'BlackHole'
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{subhead}Trap Filer Deletes:
With this option on, Black Hole will intercept all occasions on which you select 'Delete' from a Filer menu (i.e. when you delete a file in the normal way). The file will be copied to the Bin directory before being deleted.
There are a few points to note about this:
1) The wipe options for this are taken from the filer, not Black Hole's internal Config window.
2) Due to the way it works, all directory structure is lost.
3) Deleting today's bin directory from the Filer menu with this option On will simply cause the directory to be copied inside itself. UNLESS your Bin directory is inside Wimp$ScrapDir.
4) To prevent complications, this option is temporarily turned OFF during any Black Hole operation involving deletions. If I did not do this, every file would be copied twice.
5) This bit will also intercept any delete operations carried out from the command line.
{subhead}Show Sprite:
With this ON, a sprite will be placed on the iconbar next to the Black Hole icon. This sprite will have the word On or Off under it to indicate the current state of the above option. Clicking SELECT on this icon will toggle the state of the option. Clicking MENU will open a menu with a 'Remove' option which removes the sprite from the iconbar. This does not turn Singularity off.
{subhead}Remove at Exit:
With this ON, the BlackHole module will be killed when you quit Black Hole. I recommend that you do this.
{subhead}Report:
With this option ON, every time a file is captured by this method a small window will open to inform you which file has been caught. The window will close after a short time, or you can close it by clicking on its OK button.
{subhead}Ignore ADFS floppy discs:
Trapping deletions from floppy discs can be a slow process and it is very rare that you would want to do this. Turn this option on to stop Singularity applying to ADFS floppy discs (most floppy discs are ADFS).
{subhead}File Systems to Ignore:
Using this you can set up a list of up to 12 filing systems that are immune from being trapped by Singularity.
To add a filing system to the list, click on Add... This opens a menu of all the currently resident filing systems (eg ADFS, RAM if you have a RAM disc.) Select one and it will be added to the list. The last entry in the menu is a writeable icon into which you can type the name of any other filing system
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The name of the filing system is what appears at the very left of a directory heading - eg for the directory ADFS::IDEDisc4.$ the filing system is ADFS.
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{title}Compatibility Issues:
Singularity has been tested with as many filing systems as possible. Two problems are known about:
1) Singularity cannot differentiate between an Image filing system and it's parent. E.g. a PC emulator DOS partition looks to Singularity like an ADFS disc, even though it's under the control of DOSFS.
2) If you use SparkFS to create archives in the 'Spark Dir' format and delete any files from there, Singularity will copy them over in COMPRESSED form. This is due to the way this type of Archive is controlled by SparkFS. The same may be true of certain versions of ArcFS, but I haven't tried it 'cos my version's read only.
With normal archives (and with CFS) the files are decompressed on the fly.
3) RISC OS 3 implements a lot of devices as pseudo-filing systems. One example is the parallel port. Singularity will ignore all the device filing systems that I currently know about.
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The code to do this is quick and therefore does not measurably slow down
the response of these systems.
For insterested parties, the filing systems (and their numbers) that are ignored are:
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NetPrint (12)
Null (13)
Printer (14)
Serial (15)
Vdu (17)
RawVdu (18)
Kbd (19)
RawKbd (20)
DeskFS (21)
Computer Concepts RomFS (22)
Streamer (25)
Digitiser (27)
Scanner (28)
PipeFS (47)
DeviceFS (53)
Parallel (54)
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{title}The BlackHole module.
As mentioned above, the Filer 'Delete' trapping is controlled by a module called BlackHole. Here, for the interested, are details.
BlackHole provides the following commands.
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*BinOn, *BinOff - The functions of which should be obvious.
*BinStatus - Which tells you whether the Bin is currently on or off.
*BinToggle - Toggles the On/Off status of the bin.
*BinIgnore - Takes one parameter, which is the NAME of a filing system to be ignored.
*BinIgnoreClear - Clears the list of filing systems to ignore
*BinIgnoreADFSFloppies
*BinCatchADFSFloppies - both of which are self-explanatory.
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You also need to ensure that the System Variable BlackHole$BinDir is set to point to the root bin directory for TODAY. Black Hole does this automatically
If you use *BinIgnore you MUST check that the list of filing system names is no more than 128 bytes long (one byte for each character in the name, plus one more). Black Hole does this, and if you don't you could cause horrible things to happen.
{subhead}Points to note:
BlackHole does a *BinOFF before every delete operation it does, then does *BinON if necessary when it has finished. This is the only way I can think of to stop it copying all the files twice. I can't let *BinOn do all the copying because a) Some people won't want to use it, (b) all directory structure is lost.
*BinOn will ignore all disc operations which take place in Wimp$ScrapDir. If I didn't do this, all the temporay files placed in Wimp$ScrapDir by applications would be copied to the bin before being deleted. This is not particulary useful, and I have seen applications crash because of this. To this end, you should make sure that if you own any applications which allow you to define a scrap directory just for them, you should define it somewhere in Wimp$ScrapDir.
