STKPICK


Synopsis


Pick an object from a snapshot in a given level of the Undo stack

Stack Diagram


Input Stack Output Stack
Isnapshot Ilevel O
Level 2 Level 1 Level 1
Type Command
Parallel list processing Group 1
Affected by flags None

Description


The STKPICK command retrieves an object at a given level from a given snapshot on the Undo stack.

The command has little utility in interactive mode, since each time a command is typed and XEQted a snapshot of the stack is pushed on the Undo stack, altering the position of the intended snapshot.

Compatibility


This command is new in newRPL and does not exist in userRPL.

Usage


The following program

« 10 11 12 13
  STKPUSH
  CLEAR
  "ABC"
  STKPUSH
  CLEAR
  2 3 STKPICK
»

will PICK the third element (level 1 argument) from snapshot on level 2 (Level 2 argument) of the Undo stack, resulting in the number 11 being left on the current stack.

Related Commands


Stack manipulation 27 5 NEW

Command Short Description
CLEAR Remove all objects from the stack
DEPTH Get the current stack depth
DROP Remove an object from the stack
DROP2 Remove two objects form the stack
DROPN Remove N objects from the stack
DUP Duplicate an object on the stack
DUP2 Duplicate two objects on the stack
DUPDUP Duplicate the same object twice on the stack
DUPN Duplicate a group of N objects
NDUPN Replicate one object N times and return N
NIP Remove object at level 2 on the stack
OVER Duplicate object at level 2 on the stack
PICK Duplicate object at position N on the stack
PICK3 Duplicate object at level 3 on the stack
ROLL Move object at level N to level 1
ROLLD Move object from level 1 to level N
ROT Move object from level 3 to level 1
SWAP Exchange objects in levels 1 and 2
UNPICK Move object from level 1 to level N.
UNROT Move object from level 1 to level 3
IFT Evaluate objects on the stack conditionally
IFTE Evaluate objects on the stack conditionally
STKPUSH Push a snapshot of the current stack on the undo stack NEW
STKPOP Pop a stack snapshot from the undo stack NEW
STKDROP Drop a snapshot from the undo stack NEW
STKPICK Copy snapshot in level N to the current stack NEW
STKDEPTH Get the depth of the undo stack NEW
  • manual/chapter6/stack/cmd_stkpick.txt
  • Last modified: 2019/10/22 15:24
  • by jojo1973