[fpc-pascal] pointer to anything

spir ☣ denis.spir at gmail.com
Fri Apr 23 15:08:52 CEST 2010

On Fri, 23 Apr 2010 08:17:21 -0400
Doug Chamberlin <dougchamberlin at earthlink.net> wrote:

> On 4/23/2010 3:33 AM, spir ☣ wrote:
> > Say I want to implement a kind of linked list which node data may be anything. Thus I cannot store data on place (in nodes), indeed; so it should be referenced. But pointers themselves are supposed to be typed. So, how can I do that?
> >    
> The key to solving this problem is to answer the question "How will I 
> know what type of data that pointer points to?" Once you determine what 
> is being pointed to you can cast Pointer^ to that type and all should work.
> I would use Pointer as an untyped pointer to anything and ignore the 
> warning. Perhaps you can turn off that warning for this code segment 
> since you are doing this intentionally.

Thank you for both answers. 
Are there kinds of untyped data structures in the library (such as sequence/list, table/mapping/hash/dictionary). I'd like to see how they're implemented.
As a detail, my need is not necessarily the collection to be untyped, but the type to be known and/or specified at runtime. So, it is closer to what is sometimes called "generics". I want to implement the container algorithms once only, since they don't depend on the type of the content. Then I may specialise eg a Sequence type into one for strings to add a join method.


vit esse estrany ☣


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