[Info-vax] DEC Basic and dynamic memory ?

[Richard Maher]

On 29/01/2022 3:57 am, Simon Clubley wrote:
> On 2022-01-28, Dave Froble <davef at tsoft-inc.com> wrote:
>> On 1/28/2022 12:31 PM, John Reagan wrote:
>>> 4) As we've discussed the BASIC cross-compiler is still not available due to G2L not being
>>> able to totally handle how the BASIC MAP statement is described to GEM.  The GEM to
>>> LLVM module for common blocks is radically different.  Could you write a DIRECTORY
>>> replacement in BASIC without using MAP?
>>
>> Why, yes, I'm rather sure I could.  For example, from one of my routines:
>>
>>           RECORD FABBLK                                   !
>>           RECORD NAMBLK                                   !
>>           RECORD FIBBLK                                   !  FIB structure
>>
>> And now I'm waiting for you to say that the Basic RECORD statement has the same
>> problems as MAP.
>>
> 
> How easy is it in DEC Basic to build a tree of (say) 1000 nodes of
> a custom data structure in dynamic memory and then walk the tree
> either depth-first or breadth-first ?
> 
> I've had a quick look at the dynamic storage section of the DEC Basic user
> manual, but I don't see how you link a set of nodes together into a tree.
> However, as mentioned previously, I don't know DEC Basic and searching
> for the word pointer didn't reveal anything appropriate, so I assume
> it's another keyword I am not aware of.
> 
> In addition, how easy is this to do if the nodes are not all of the
> same record type, but have a common tag at the start of each record
> to say what kind of record it actually is ? I see you have variant
> records in DEC Basic. Do they also work in a dynamic memory based
> tree structure ?
> 
> Simon.
> 

I'd employ Lib$ malloc, realloc, and calloc