Z

*Zap

A global variable holding a list and a pathname. If given, and the value of *Solo is NIL, external symbols which are no longer accessible can be collected in the CAR, e.g. during DB tree processing, and written to the file in the CDR at the next commit. A (typically periodic) call to zap_ will clean them up later.

: (setq *Zap '(NIL . "db/app/_zap"))
-> (NIL . "db/app/_zap")

(zap 'sym) -> sym

"Delete" the symbol sym. For internal symbols, that means to remove it from the current namespace, effectively transforming it to a transient symbol. For external symbols, it means to mark it as "deleted", so that upon a later commit it will be removed from the database file. See also intern.

: (de foo (Lst) (car Lst))          # 'foo' calls 'car'
-> foo
: (zap 'car)                        # Delete the symbol 'car'
-> "car"
: (pp 'foo)
(de foo (Lst)
   ("car" Lst) )                    # 'car' is now a transient symbol
-> foo
: (foo (1 2 3))                     # 'foo' still works
-> 1
: (car (1 2 3))                     # Reader returns a new 'car' symbol
!? (car (1 2 3))
car -- Undefined
?

(zapTree 'sym)

Recursively deletes a tree structure from the database. See also tree, chkTree and prune.

: (zapTree (cdr (root (tree 'nm '+Item))))

(zap_)

Delayed deletion (with zap) of external symbols which were collected e.g. during DB tree processing. An auxiliary file (with the name taken from the CDR of the value of *Zap, concatenated with a "_" character) is used as an intermediary file.

: *Zap
-> (NIL . "db/app/Z")
: (call 'ls "-l" "db/app")
...
-rw-r--r-- 1 abu abu     1536 2007-06-23 12:34 Z
-rw-r--r-- 1 abu abu     1280 2007-05-23 12:15 Z_
...
: (zap_)
...
: (call 'ls "-l" "db/app")
...
-rw-r--r-- 1 abu abu     1536 2007-06-23 12:34 Z_
...

(zero var ..) -> 0

Stores 0 in all var arguments. See also one, on, off and onOff.

: (zero A B)
-> 0
: A
-> 0
: B
-> 0