Re: [sqlite] How to create connection life-time object?

[Dušan Paulovič]

What I need is 'install and don't care' because I use many C++ classes
as lifetime objects.
I think that my solution does work now well, but if there would be a way to
avoid use of SQL parser, it would be better.


2013/7/27 Max Vlasov 

> On Fri, Jul 26, 2013 at 9:56 PM, Dušan Paulovič 
> wrote:
>
> > Thanks for suggestion, but:
> > 1.) one object is not linked to one connection
> >
>
> If you have your own memory management, it's not a problem since the scheme
> I described is basically just a storage of pointers. To free or not to free
> (if the pointer points to a disposable entity) is your decision at your
> chosen time. But if you want automatic reference counting (so when a
> pointer not referenced anymore, it would be automatically deallocated),  I
> agree, the proposal is not good. Probably using your own global structure
> not related to sqlite is less pain.
>
>
> > 2.) object is not destroyed together with connection
> >
>
> The same, you're free to use the table just as pointers storage
>
> Max
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Re: [sqlite] How to create connection life-time object?

[Max Vlasov]

On Fri, Jul 26, 2013 at 9:56 PM, Dušan Paulovič  wrote:

> Thanks for suggestion, but:
> 1.) one object is not linked to one connection
>

If you have your own memory management, it's not a problem since the scheme
I described is basically just a storage of pointers. To free or not to free
(if the pointer points to a disposable entity) is your decision at your
chosen time. But if you want automatic reference counting (so when a
pointer not referenced anymore, it would be automatically deallocated),  I
agree, the proposal is not good. Probably using your own global structure
not related to sqlite is less pain.


> 2.) object is not destroyed together with connection
>

The same, you're free to use the table just as pointers storage

Max
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Re: [sqlite] How to create connection life-time object?

[Dušan Paulovič]

Thanks for suggestion, but:
1.) one object is not linked to one connection
2.) object is not destroyed together with connection

Dusan


2013/7/26 Max Vlasov 

> Hi, Dušan
>
>
> On Thu, Jul 25, 2013 at 2:39 PM, Dušan Paulovič 
> wrote:
>
> > Hello, is there a way to somehow set a connection life-time object?
> > ...
> >
> >
> > It would be fine to have something like:
> > int sqlite3_set_lifetime_object(
> >   sqlite3 *db,  /*db connection*/
> >   const char *zObjectName,  /*utf8 name of object*/
> >   void *pObject,/*if NULL, object is removed*/
> >   void(*xDestroy)(void*)/*destructor*/
> > );
> >
> > void * sqlite3_get_lifetime_object(
> >   sqlite3 *db,  /*db connection*/
> >   const char *zObjectName   /*utf8 name of object*/
> > );
> >
>
>
>
> How about temporary memory table just for the task of storing your objects.
>
> You initialization code for particular connection
>   Attach ':memory:' as MyObjectStorage
>   Create table MyObjectStorage.[objects] (Name Text, Ptr Text)
>
> Your code for inserting an object
>   Insert into MyObjectStorage.[objects] (Name, Ptr) VALUES ('obj1',
> '0x12345678')
>
> This code will query the pointer
>   select Ptr from MyObjectStorage.[objects] where Name='obj1'
>
> The only convention rule here will be the name of the attached db so no
> other databases (or instances of the same storage) should use this name.
>
> Max
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Re: [sqlite] How to create connection life-time object?

[Max Vlasov]

Hi, Dušan


On Thu, Jul 25, 2013 at 2:39 PM, Dušan Paulovič  wrote:

> Hello, is there a way to somehow set a connection life-time object?
> ...
>
>
> It would be fine to have something like:
> int sqlite3_set_lifetime_object(
>   sqlite3 *db,  /*db connection*/
>   const char *zObjectName,  /*utf8 name of object*/
>   void *pObject,/*if NULL, object is removed*/
>   void(*xDestroy)(void*)/*destructor*/
> );
>
> void * sqlite3_get_lifetime_object(
>   sqlite3 *db,  /*db connection*/
>   const char *zObjectName   /*utf8 name of object*/
> );
>



How about temporary memory table just for the task of storing your objects.

You initialization code for particular connection
  Attach ':memory:' as MyObjectStorage
  Create table MyObjectStorage.[objects] (Name Text, Ptr Text)

Your code for inserting an object
  Insert into MyObjectStorage.[objects] (Name, Ptr) VALUES ('obj1',
'0x12345678')

This code will query the pointer
  select Ptr from MyObjectStorage.[objects] where Name='obj1'

The only convention rule here will be the name of the attached db so no
other databases (or instances of the same storage) should use this name.

Max
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