Problems with Generic Collection class.

[BombDrop]

I'm working on a system that has 4 different types of client they
have mostly the same attributes so I decided to create an interface
IClient for them to implement and then just add the differing
attributes as needed to each client class.

Now I get the Client information from a DB and Load them into a Generic
dictionary

The class looks like so

class Class1<T: Dictionary<int, Twhere T:IClient

{

private IndemnityScheme scheme;

public Class1(Indemnit yScheme scheme)

{

this.scheme = scheme;

}

public int Load()

{

// "procIndemnityC lientSelect";

DataBaseAccess dba = new DataBaseAccess( this.scheme);

SqlDataReader reader =
dba.LoadData("p rocPrsymClientS elect");

SmartDataReader smartReader = new SmartDataReader (reader);

while (smartReader.Re ad()) {

AceClient newClient = new AceClient(this. scheme);

newClient.Clien tshort = smartReader.Get String("Client
Short Name");

newClient.Clien tname = smartReader.Get String("Client
Name");

newClient.Clien tref = smartReader.Get Int32("client
ref");

newClient.Addre ssLine1 = smartReader.Get String("Address
Line 1");

newClient.Addre ssLine2 = smartReader.Get String("Address
Line 2");

newClient.Addre ssLine3 = smartReader.Get String("Address
Line 3");

newClient.Addre ssLine4 = smartReader.Get String("Address
Line 4");

newClient.Addre ssLine5 = smartReader.Get String("Address
Line 5");

newClient.Addre ssLine6 = smartReader.Get String("Address
Line 6");

newClient.Telep hone = smartReader.Get String("Telepho ne
No");

newClient.PostC ode = smartReader.Get String("post
code");

newClient.Conta ct = smartReader.Get String("Contact ");

// newClient.Handl er = smartReader.Get String("Handler ");

newClient.Joind ate = smartReader.Get String("Join
Date");

newClient.Leavi ngdate = smartReader.Get String("leaving
Date");

newClient.Salut ation =
smartReader.Get String("salutat ion");

newClient.Email = smartReader.Get String("Email") ;

newClient.Comme nts = smartReader.Get String("comment s");

base.Add(newCli ent.Clientref, newClient);

}

smartReader.Clo se();

smartReader = null;

dba = null;

return base.Count;



}

}

I call the class in my program like so

AceClient c = new AceClient(Indem nityScheme.ACE) ;

Class1<AceClien tcl = new
Class1<AceClien t>(IndemnitySch eme.ACE);

cl.Load();

foreach (AceClient ac in cl.Values) {

System.Diagnost ics.Debug.Write Line(ac.Clients hort);

}

Nothing fancy just want to loop throught the collection but on trying
to complie I get an error.

This is the line of code that errors

base.Add(newCli ent.Clientref, newClient);

Error 24 The best overloaded method match for
'System.Collect ions.Generic.Di ctionary<int,T> .Add(int, T)' has some
invalid arguments

Error 25 Argument '2': cannot convert from 'Prsym.AceClien t'
to 'T'

Can anyone tell me what I am doing wrong??

[Daniel]

Does 'Prsym.AceClien t' implement the IClient interface?


"BombDrop" <bu************ *@gmail.comwrot e in message
news:11******** **************@ 11g2000cwr.goog legroups.com...

I'm working on a system that has 4 different types of client they
have mostly the same attributes so I decided to create an interface
IClient for them to implement and then just add the differing
attributes as needed to each client class.

Now I get the Client information from a DB and Load them into a Generic
dictionary

The class looks like so

class Class1<T: Dictionary<int, Twhere T:IClient

{

private IndemnityScheme scheme;

public Class1(Indemnit yScheme scheme)

{

this.scheme = scheme;

}

public int Load()

{

// "procIndemnityC lientSelect";

DataBaseAccess dba = new DataBaseAccess( this.scheme);

SqlDataReader reader =
dba.LoadData("p rocPrsymClientS elect");

SmartDataReader smartReader = new SmartDataReader (reader);

while (smartReader.Re ad()) {

AceClient newClient = new AceClient(this. scheme);

newClient.Clien tshort = smartReader.Get String("Client
Short Name");

newClient.Clien tname = smartReader.Get String("Client
Name");

newClient.Clien tref = smartReader.Get Int32("client
ref");

newClient.Addre ssLine1 = smartReader.Get String("Address
Line 1");

newClient.Addre ssLine2 = smartReader.Get String("Address
Line 2");

newClient.Addre ssLine3 = smartReader.Get String("Address
Line 3");

newClient.Addre ssLine4 = smartReader.Get String("Address
Line 4");

newClient.Addre ssLine5 = smartReader.Get String("Address
Line 5");

newClient.Addre ssLine6 = smartReader.Get String("Address
Line 6");

newClient.Telep hone = smartReader.Get String("Telepho ne
No");

newClient.PostC ode = smartReader.Get String("post
code");

newClient.Conta ct = smartReader.Get String("Contact ");

// newClient.Handl er = smartReader.Get String("Handler ");

newClient.Joind ate = smartReader.Get String("Join
Date");

newClient.Leavi ngdate = smartReader.Get String("leaving
Date");

newClient.Salut ation =
smartReader.Get String("salutat ion");

newClient.Email = smartReader.Get String("Email") ;

newClient.Comme nts = smartReader.Get String("comment s");

base.Add(newCli ent.Clientref, newClient);

}

smartReader.Clo se();

smartReader = null;

dba = null;

return base.Count;



}

}

I call the class in my program like so

AceClient c = new AceClient(Indem nityScheme.ACE) ;

Class1<AceClien tcl = new
Class1<AceClien t>(IndemnitySch eme.ACE);

cl.Load();

foreach (AceClient ac in cl.Values) {

System.Diagnost ics.Debug.Write Line(ac.Clients hort);

}

Nothing fancy just want to loop throught the collection but on trying
to complie I get an error.

This is the line of code that errors

base.Add(newCli ent.Clientref, newClient);

Error 24 The best overloaded method match for
'System.Collect ions.Generic.Di ctionary<int,T> .Add(int, T)' has some
invalid arguments

Error 25 Argument '2': cannot convert from 'Prsym.AceClien t'
to 'T'

Can anyone tell me what I am doing wrong??

[Larry Lard]

BombDrop wrote:

I'm working on a system that has 4 different types of client they
have mostly the same attributes so I decided to create an interface
IClient for them to implement and then just add the differing
attributes as needed to each client class.

Sounds OK.

Now I get the Client information from a DB and Load them into a Generic
dictionary

The class looks like so

class Class1<T: Dictionary<int, Twhere T:IClient

OK, so a Class1<Tis a Dictionary<int, Twith some extras.

public int Load()
{

[...]

while (smartReader.Re ad()) {

AceClient newClient = new AceClient(this. scheme);

Hmm. We are in Class1<Tso we could be dealing with *any* of the
various implementers of IClient, but we always create a AceClient?

newClient.Clien tshort = smartReader.Get String("Client
Short Name");

[...]

base.Add(newCli ent.Clientref, newClient);

base here is a Dictionary<int, T>. Only if T is AceClient will this
addition be possible.

I call the class in my program like so
AceClient c = new AceClient(Indem nityScheme.ACE) ;

Class1<AceClien tcl = new
Class1<AceClien t>(IndemnitySch eme.ACE);

cl.Load();

[...]

Nothing fancy just want to loop throught the collection but on trying
to complie I get an error.

So at run time *in this case*, T will be AceClient; but the compiler
isn't to know that.

This is the line of code that errors

base.Add(newCli ent.Clientref, newClient);

Error 25 Argument '2': cannot convert from 'Prsym.AceClien t'
to 'T'

Can anyone tell me what I am doing wrong??

Since the compiler wants *compile time* type safety, it doesn't matter
that you do actually have T as an AceClient in your particular case.

The solution:
- give all IClient implementors a parameterless constructor. Move the
code in the scheme-accepting ctor to the 'set' part of a property for
the scheme.
- add the 'new' constraint in the declaration of Class1 thus:

class Class1<T: Dictionary<int, Twhere T:IClient, new()
// "When you use the new() constraint with other constraints, it must be
specified last"

- in the Load method, create a new T (rather than a new AceClient) and
set its scheme.

Note that (unfortunately) you can't have a constraint that says 'type T
must have a ctor that accepts a scheme'; you can only require T to have
a parameterless ctor. Which is why you'll have to move the
scheme-setting code.

--
Larry Lard
la*******@googl email.com
The address is real, but unread - please reply to the group
For VB and C# questions - tell us which version

[Jon Skeet [C# MVP]]

BombDrop wrote:

I'm working on a system that has 4 different types of client they
have mostly the same attributes so I decided to create an interface
IClient for them to implement and then just add the differing
attributes as needed to each client class.

Now I get the Client information from a DB and Load them into a Generic
dictionary

<snip>

Can anyone tell me what I am doing wrong??

Yes - you're trying to add an AceClient to a dictionary which may not
be of type Dictionary<int, AceClient>.

I suspect you actually just want it to be a Dictionary<int, IClientor
Dictionary<int, AceClientinstea d of keeping it generic, given that
what you're actually adding is always an AceClient.

Jon