[PyQt] Wrap with SIP in-out string parameters in class method

[Phil Thompson]

On Tue, 11 Dec 2012 12:56:51 +0200, Alexander Bruy
<alexander.bruy at gmail.com> wrote:
> Hi all,
> 
> I'm new to SIP and have some troubles with wrapping class in SIP.
> I need to declare some parameters as in and out.
> 
> Here is class header
> 
> class AuthData
> {
>   public:
>     virtual ~AuthData();
>     bool get( QString dbName, QString &username, QString &password,
> QString message = QString::null );
>     void put( QString dbName, QString username, QString password );
>     static AuthData *instance();
>   protected:
>     virtual bool request( QString dbName, QString &username, QString
> &password, QString message = QString::null ) = 0;
>     void setInstance( AuthData *theInstance );
>   private:
>     QMap< QString, QPair<QString, QString> > mAuthCache;
>     static AuthData *smInstance;
> };
> 
> And here is my sip file
> 
> class AuthData
> {
> %TypeHeaderCode
> #include <authdata.h>
> %End
> 
>   public:
>     virtual ~AuthData();
>     bool get( QString dbName, QString &username /In,Out/, QString
> &password /In,Out/, QString message = QString::null );
>     void put( QString dbName, QString username, QString password );
>     static AuthData *instance();
> 
>   protected:
>     virtual bool request( QString dbName, QString &username /In,Out/,
> QString &password /In,Out/, QString message = QString::null ) = 0;
>     void setInstance( QgsCredentials *theInstance );
> };
> 
> I want to make username and password in-out parameters. With this file
> all compiled
> without any errors, but in runtime when I try to get username and
> password from Python
> I get
> 
>>> res, u, p = AuthData.instance().get(myDbName, "", "")
>>>> print p
> Traceback (most recent call last):
>   File "<input>", line 1, in <module>
> RuntimeError: underlying C/C++ object has been deleted
> 
> Is it possible to implement such behaviour with SIP?
> 
> I use Qt 4.8.2, SIP 4.13.2 and Python 2.7.3
> 
> 
> Thanks

Try passing QStrings as arguments rather than Python strings.

Phil