Hidden directory?
Shayne
I've read the FAQ on the hidden directory in
a 48GX and I am still a little hazy on details...
I'm going to play around but some info would
be nice, such as if you back up the home
directory does this include the hidden directory?
How do you move files or variables into the hidden
directory... with the memory browser?
If a program is placed in the hidden directory and
a custom menu soft key is assigned to run that program
will it be able to find and run it without help?
Anything else I should know.
Yours hesitantly,
Shayne.
:)
ramon...@my-deja.com
If you backup, you also store the variables of the hiddden directory
(assigned keys, alarms..)
As far as know, you need to know systemrpl to make use of this
directory, unless you use a memory browser.The commands in system are:
RclHiddenVar, StoHiddenVar. Be very carefull with this and forget it if
you don't know SystemRPL
You can't execute a program stored in the hidden directory just by
typing its name, as you would do in other cases. Again you need special
programs or SystemRPL
Sent via Deja.com http://www.deja.com/
Before you buy.
John H Meyers
> I've read the FAQ on the hidden directory in
> a 48GX [or 49G] and I am still a little hazy on details...
> if you back up the home directory
> does this include the hidden directory?
Yes, HP's hidden directory is the last variable in your
HOME directory, but because it has a "null name" (empty string),
most functions (such as the VAR menu, the VARS command, etc.)
are programmed to ignore it and not show it -- which is
what makes this directory "hidden"!
Programs called "variable hiders" take advantage of the fact
that *any* variable having a "null name" will cause the
VAR menu (or the VARS command) to just stop at that point,
showing neither that nor any subsequent variable, so such
a null-named variable can be used to "hide" remaining variables.
Fortunately, the internal operating system does not locate
the HP hidden directory by looking for its name, but rather
by its being the first object in the HOME directory memory space,
so variable hiders can coexist with the HP hidden directory
(but some programs, even PCT for the 48, use the null name instead!)
> How do you move files or variables into the hidden
> directory -- with the memory browser?
No, HP's memory browser (48) and Filer (49) obey the idea that
the hidden directory should be hidden, and therefore don't show it!
> If a program is placed in the hidden directory and
> a custom menu soft key is assigned to run that program
> will it be able to find and run it without help?
Since the hidden directory is a subdirectory of HOME,
and since variables in (other) subdirectories of HOME
are *not* in the "search path" for unresolved variable names
(the search normally proceeds to *higher* directories,
and stops after searching HOME), you normally thus can *not*
locate by name any variables in the hidden directory.
If you want to use a "path name" for the program, it would
need to be { HOME '' 'progname' }, but the problem in UserRPL
would be to make the "null name" part of that list, plus the fact
that if you were to use a variable hider in HOME, then this
"path name" scheme would fail anyway.
Although you can assign a program such as \<< 'name' HRCL EVAL \>>
to a key, I'd recommend putting all programs which you want to hide
into HOME instead, where they can always be accessed directly by name,
even if hidden, and then use a variable hider. Not only will this
make your programming life easier, but it will also avoid inevitable
disappointment when sometimes your hidden directory will just
be wiped out completely, and a new one (empty) will be created
instead; this generally happens during every "Recover Memory"
attempt, for example.
> Anything else I should know?
Although I have just recommended against storing your own variables
in the hidden directory, now I'll supply programs for doing this
anyway, so that everyone can play around and get into trouble :)
My version of HVARS avoids listing the final three "reserved"
variables in the hidden directory (Alarms, UserKeys, UserKeys.CRC),
which store what their names indicate, but in a form which you
can't use anyway in UserRPL; if you were to try to change, purge
or ORDER these variables, your calculator would crash, so
why list them with HVARS? You can, however, recall them
using 'Alarms' HRCL etc., to satisfy your curiosity
as to what these lists contain (exact details about these lists
have been posted in the past, and might be found at hpcalc.org).
No doubt someone will also post how to go directly into the
hidden directory, making it your current directory; I don't
see any reason to ever bother doing this, since you can
do all useful operations via the other means provided here,
and it's easier and safer to just do the standard operations
(VARS, RCL, STO, PURGE) "remotely," without ever needing
to change the current directory at all.
Basically, the system uses the hidden directory itself to
store things while performing its own functions for you. Some
libraries or other programs save options there (e.g. MathTools),
much as Windows saves information in a hidden "Registry";
my program for "saving unlimited commands" saves its command history
there, and my "triangle solver" keeps its solution variables there
(to avoid cluttering up your working directory), etc.
I would always regard the contents of the hidden directory as
"perishable," however, and would suggest that alternate locations
be used to save anything vital, simply because of the fact that
the system itself may delete and re-create an empty
hidden directory for you, as mentioned above.
To make some programs for hidden directory access:
HOME
\<< Hidden VARS 1 OVER SIZE 3 - SUB \>> 'HVARS' STO
\<< Hidden RCL \>> 'HRCL' STO
\<< Hidden STO \>> 'HSTO' STO
\<< Hidden PURGE \>> 'HPURGE' STO
\<< Hidden EVAL \>> 'HEVAL' STO
Try "VARS" \<< OBJ\-> \>> HEVAL to see why this could be useful
(in place of STR\-> or OBJ\-> on unknown strings).
Choose *one* version of 'Hidden' (for your calc model):
256 ATTACH @ for HP49, optionally install ASC-> for HP48
"D9D201DF603C073B2130" H\-> 'Hidden' STO @ HP49 version
"D9D201DF6073046B2130ADFB" ASC\-> 'Hidden' STO @ HP48 version
Another HP48 version (use if ASC-> is not handy):
\<< #64037h #6FD1h SYSEVAL SYSEVAL \>> 'Hidden' STO @ HP48 only!
SysRPL source for 'Hidden' :: COLA WithHidden ;
Note the "standard warning":
Incorrect addresses (the hex info above) could crash your calc;
a backup is recommended (besides, everyone always puts this off,
until one minute after a crash :)
> Yours hesitantly
"He who hesitates is lost" :)
-----------------------------------------------------------
With best wishes from: John H Meyers <jhme...@mum.edu>