Re: scheme memory address

[Gianmaria Lari]

On Tue, 9 Apr 2019 at 11:13, David Kastrup <address@hidden> wrote:

Gianmaria Lari <address@hidden> writes:

> On Tue, 9 Apr 2019 at 10:45, David Kastrup <address@hidden> wrote:
>
>> Gianmaria Lari <address@hidden> writes:
>>
>> > Suppose I write
>> >
>> >
>> > #(define x '(1 2 3))
>> >
>> >
>> > is there any way in scheme to print the memory address where x is
>> pointing
>> > to? (where is allocated the first element of the list)
>>
>> What do you need it for?  If it is for identification, (hashq x
>> 1000000000) should usually do a reasonably good job.
>>
>
> I tried, it looks working. (Yes, it's for identification)
>
> And is there any way to print the memory address of x? (If I remember
> correctly was something like &x in c++).

object-address maybe.  But it's not like you can use it for anything.

If I didn't make any mistakes, this code print the "address" of the first element of the list x and the "address" of the first element pointed by the parameter "lst" of the "foo" function.

\version "2.21.0"

#(define x '(1 2 3))

#(define (foo lst) (display (hashq lst 1000000000))) 

 

#(display (hashq x 1000000000))#(newline)

#(foo x)

 

The two instructions

#(display (hashq x 1000000000))#(newline)

#(foo x)

print the same value because foo is called with x as argument and x and lst refer to the same address.

I wanted to print the address of the variable x and then the address of the parameter lst just to show that x and lst have different address (so  x is passed by value. I could infer the same assigning to lst a new value and see that at the exit of the function x didn't get update). I hope I didn't say nothing wrong.

Best regards, g.