Postgres Pro
Downloads
Home   >   mailing lists

Thread: Re: [INTERFACES] libpq++ ---- PgDatabase instance problem

Re: [INTERFACES] libpq++ ---- PgDatabase instance problem

From
inkle c
Date:
Well, this is where the problem comes because PgDatabase() is a
protected constructor, myclass doesn't inherit from PgDatabase. In
simple words:
==============================================
class myclass {   public:          myclass();   private:          PgDatabase db;
}

myclass::myclass():db(NULL){
some-other-stuff-goes-here
}; 
===============================================
the above codes causes me trouble as I described 
below, any ideas how to fix it? I also tried
PgDatabase db as a global variable and init it to
be NULL, but this causes the same problem.

Thanks.

inkle 

--- Patrick Welche <prlw1@newn.cam.ac.uk> wrote:
> inkle c wrote:
> > 
> > Hi,
> > 
> > I am writing a small class which has a PgDatabase
> > instance as its private member, and in the
> constructor,
> > I init it to be NULL (i.e.,
> > myclass::myclass():PgDatabaseInstanceMember(NULL)
> ), this causes a core
> > dump, what's wrong with that?
> 
> I'm not too sure what you want, but how about
> 
> myclass::myclass():PgDatabase()
> 
> ?
> 
> Cheers,
> 
> Patrick
> 

__________________________________________________
Do You Yahoo!?
Bid and sell for free at http://auctions.yahoo.com

Re: [INTERFACES] libpq++ ---- PgDatabase instance problem

From
"Patrick Welche"
Date:
inkle c wrote:
> 
> Well, this is where the problem comes because PgDatabase() is a
> protected constructor, myclass doesn't inherit from PgDatabase. In
> simple words:
> ==============================================
> class myclass {
>     public:
>            myclass();
>     private:
>            PgDatabase db;
> }
> 
> myclass::myclass():db(NULL){
> some-other-stuff-goes-here
> }; 
> ===============================================
> the above codes causes me trouble as I described 
> below, any ideas how to fix it? I also tried
> PgDatabase db as a global variable and init it to
> be NULL, but this causes the same problem.

As far as I remember if you send NULL, you are saying that
the string that PgDatabase uses is empty rather than being say
"dbname=test", and that it should try to connect ?using defaults?,
whereas if you just db(), you are saying, this instance isn't
initialised, create it, but don't connect. I'm afraid I can't
UTSL at the moment...

Cheers,

Patrick

Re: [INTERFACES] libpq++ ---- PgDatabase instance problem

From
Yu Cao
Date:
Sounds like you can just have a pointer to PgDatabase in your class
(private: PgDatabase* db_ptr;), and initialize that to the NULL
pointer. Later on you instantiate PgDatabase with "new".

--Yu Cao

On Fri, 20 Aug 1999, inkle c wrote:

> Well, this is where the problem comes because PgDatabase() is a
> protected constructor, myclass doesn't inherit from PgDatabase. In
> simple words:
> ==============================================
> class myclass {
>     public:
>            myclass();
>     private:
>            PgDatabase db;
> }
> 
> myclass::myclass():db(NULL){
> some-other-stuff-goes-here
> }; 
> ===============================================
> the above codes causes me trouble as I described 
> below, any ideas how to fix it? I also tried
> PgDatabase db as a global variable and init it to
> be NULL, but this causes the same problem.
> 
> Thanks.
> 
> inkle 
> 
> --- Patrick Welche <prlw1@newn.cam.ac.uk> wrote:
> > inkle c wrote:
> > > 
> > > Hi,
> > > 
> > > I am writing a small class which has a PgDatabase
> > > instance as its private member, and in the
> > constructor,
> > > I init it to be NULL (i.e.,
> > > myclass::myclass():PgDatabaseInstanceMember(NULL)
> > ), this causes a core
> > > dump, what's wrong with that?
> > 
> > I'm not too sure what you want, but how about
> > 
> > myclass::myclass():PgDatabase()
> > 
> > ?
> > 
> > Cheers,
> > 
> > Patrick
> > 
> 
> __________________________________________________
> Do You Yahoo!?
> Bid and sell for free at http://auctions.yahoo.com
> 
> 
> ************
> 
>