chapter 7 page 138 pop pointer 1?

[nand2cy]

chapter 7 page 138 pop pointer 1?

Why it is not pop pointer 0?

push local 0
push constant 2
add
pop pointer 1
push constant 19
pop that 0

[cadet1620]

nand2cy wrote

Why it is not pop pointer 0?

push local 0
push constant 2
add
pop pointer 1
push constant 19
pop that 0

"pop pointer 0" sets the base of the this segment.
"pop pointer 1" sets the base of the that segment.

This example could have used pointer 0 and this, but the convention used by the Jack compiler is that the that segment is used for accessing array elements.

Figure 7.11 shows the convention for accessing object fields (member variables) using pointer 0 and this.

--Mark