manual:chapter6:stack:cmd_stkpick [newRPL User Manual]

Synopsis

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

Stack Diagram

Input Stack			Output Stack
I_snapshot	I_level	→	O
Level 2	Level 1	→	Level 1

Legend

Legend	Object type
O	Any object
I	Integer number
R	Real number
#	Binary number
Num	Scalar (Integer, Real or Binary number)
Z	Complex number
U	Unit
∡	Angle
A	Symbolic expression
C	Symbolic constant
V	Vector
M	Matrix
S	String
1/0	Any expression evaluating to True or False
G	Grob
F	Font
D	Binary data container
T	Tag object
L	List
cL	Case list
N	Variable name / Identifier
Dir	Directory
pDir	Packed Directory
P	Program
Lib	Library

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