8 The optional Double-Number word set

8.6.1.0440 2VARIABLE two-variable DOUBLE

( "<spaces>name" -- )

Skip leading space delimiters. Parse name delimited by a space. Create a definition for name with the execution semantics defined below. Reserve two consecutive cells of data space.

name is referred to as a "two-variable".

name Execution:

( -- a-addr )

a-addr is the address of the first (lowest address) cell of two consecutive cells in data space reserved by 2VARIABLE when it defined name. A program is responsible for initializing the contents.

See:

Rationale:

Typical use: 2VARIABLE name

Testing:

T{ 2VARIABLE 2v1 -> }T
T{ 0. 2v1 2! ->    }T
T{    2v1 2@ -> 0. }T
T{ -1 -2 2v1 2! ->       }T
T{       2v1 2@ -> -1 -2 }T

T{ : cd2 2VARIABLE ; -> }T
T{ cd2 2v2 -> }T
T{ : cd3 2v2 2! ; -> }T
T{ -2 -1 cd3 -> }T
T{ 2v2 2@ -> -2 -1 }T

T{ 2VARIABLE 2v3 IMMEDIATE 5 6 2v3 2! -> }T
T{ 2v3 2@ -> 5 6 }T

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