Casting question

[Steven Blair]

Hi,

I have the follwoing code:

( (cSqlProviderFa ctory)m_factory ).GetConnection String();
( (cODBCProviderF actory)m_factor y ).GetConnection String();

I want this to be one line only (I have quite few different classes)

Is it possible, in C# to do soemthing like this:

Type myType = m_Factory.GetTy pe();
( (myType)m_facto ry ).GetConnection String();

Regards,

Steven



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[Richard Blewett [DevelopMentor]]

Re: Casting question

Going blind here as you don't say what the relationship between the factory classes is

abstract class ProviderFactory
{
public abstract string GetConnectionSt ring();
}

class cSqlProviderFac tory : ProviderFactory
{
public override string GetConnectionSt ring();
{
return .....;
}
}

class

class cODBCProviderFa ctory : ProviderFactory
{
public override string GetConnectionSt ring();
{
return .....;
}
}

class Foo
{
ProviderFactory m_factory;
public void UseFactory()
{
string connStr = m_factory.GetCo nnectionString( );
}
}

This uses polymorphism to get the appropriate connection string only knowing about the base factory

Whether this does what you want depends on your implementation however, if this doesn't meet you requirements you'll have to give us more information.

Regards

Richard Blewett - DevelopMentor

http://www.dotnetconsult.co.uk/weblog

http://www.dotnetconsult.co.uk

Hi,

I have the follwoing code:

( (cSqlProviderFa ctory)m_factory ).GetConnection String();
( (cODBCProviderF actory)m_factor y ).GetConnection String();

I want this to be one line only (I have quite few different classes)

Is it possible, in C# to do soemthing like this:

Type myType = m_Factory.GetTy pe();
( (myType)m_facto ry ).GetConnection String();

Regards,

Steven

[Steven Blair]

Re: Casting question

I have defined an interface which all my DB classes inherit from:

public interface IDbProviderFact ory
{
IDbConnection CreateConnectio n( string connectionStrin g );
}


And a class inherits from this:

public class cSqlProviderFac tory : IDbProviderFact ory
{
public IDbConnection CreateConnectio n( string c )
{
return new SqlConnection( connectionStrin g );
}

I want each inheritted class to have its own GetConnectionSt ring, but
each version has the possibility of different parameters being passed
in.

Hope this is more helpful.

Regards,

Steven




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[Richard Blewett [DevelopMentor]]

Re: Casting question

Well I don't know if this was intentional but your design is almost how ADO.NET 2.0 is architected for the next release of .NET. Here they define a ConnectionStrin gFactory class that has all the standard things like server, database, etc and also a hashtable to put the other key/value pairs. You can override ToSTring in your version to return the complete provider specific connection string. So GetConnectionSt ring returns the factory which is used to create the bits of teh connection string.

Regards

Richard Blewett - DevelopMentor

http://www.dotnetconsult.co.uk/weblog

http://www.dotnetconsult.co.uk

I have defined an interface which all my DB classes inherit from:

public interface IDbProviderFact ory
{
IDbConnection CreateConnectio n( string connectionStrin g );
}


And a class inherits from this:

public class cSqlProviderFac tory : IDbProviderFact ory
{
public IDbConnection CreateConnectio n( string c )
{
return new SqlConnection( connectionStrin g );
}

I want each inheritted class to have its own GetConnectionSt ring, but
each version has the possibility of different parameters being passed
in.

Hope this is more helpful.

Regards,

Steven

[Chris Dunaway]

Re: Casting question

Then you should be casting to the Interface rather than to the class
name:

( (IDbProviderFac tory)m_factory ).GetConnection String();



And, by the way, your classes do not inherit from the interface, they
implement it.

Cheers