[gt-users] Attach user data to GtGenomeNodes

[Sascha Steinbiss]

Gordon Gremme wrote:
>> void gt_genome_node_add_user_data(GtGenomeNode *node,
>>                                   void *key,
>>                                   void *data,
>>                                   GtFree free_func);
>> void *gt_genome_node_get_user_data(const GtGenomeNode *node,
>>                                    void *key);
>> void gt_genome_node_release_user_data(GtGenomeNode *node,
>>                                       void *key);
> Looks good to me. Would gt_genome_node_release_user_data() also free
> the user data object?

Yes, that was my idea. The caller is responsible to ref() the object 
first or not give a GtFree callback if he/she does not want this.

>> Do you think we should introduce a free-function for the key as well,
>> like in the generic hashmap class?
> I don't think so. We should agree upon a convention on what is used as
> key. My suggestion would be the constructor method of the user data
> object.

Wouldn't that force the user to write loads of small container classes 
if he/she wants to attach more than one object of the same class? For 
example, it is not possible this way to add more than one GtStr (with 
gt_str_new constructor) to an object unless something like a 
MyMultiStrContainer class (with a unique constructor method) is created 
to hold multiple GtStr references.
OTOH, I can't think of a better solution, so I'm ok with this.

I still am unsure how to implement this in the scripting bindings 
though. In the bindings, the C constructors are not public and should 
also not be touched by a user. Also, I have to find out whether 
implementing this on the C side allows a bindings user to create his/her 
own container structures and attach them using the C interface.

> Gordon

Sascha

-- 
Sascha Steinbiss
Center for Bioinformatics
University of Hamburg
Bundesstr. 43
20146 Hamburg
Germany

Email:  steinbiss at zbh.uni-hamburg.de
URL:    http://www.zbh.uni-hamburg.de/steinbiss
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