I'm missing some nuance..

[Ian Branch 121]

Hi Team,

I want to be able to make a generic function like this..

function SetDBSessionNames(const ComponentCount: Integer; const Components: TComponent; const sSessionName: string): boolean;
begin
  //
  for var i := 0 to ComponentCount - 1 do
  begin
    //
    if (Components[i] is TEDBSession) then (Components[i] as TEDBSession).SessionName := sSessionName;
    //
    if (Components[i] is TEDBDatabase) then (Components[i] as TEDBDatabase).SessionName := sSessionName;
    //
    if (Components[i] is TnlhTable) then (Components[i] as TnlhTable).SessionName := sSessionName;
    //
    if (Components[i] is TnlhQuery) then (Components[i] as TnlhQuery).SessionName := sSessionName;
    //
    if (Components[i] is TnlhScript) then (Components[i] as TnlhScript).SessionName := sSessionName;
    //
  end;
  //
end;

That would be called like this..

  //
  SetDBSessionNames(ComponentCount, Components, sSessionName);
//

The function is in a separate function library.

Unfortunately it doesn't like  "Components" in the if.... lines. 😞

I have obviously missed or misinterpreted some aspect.

Some assistance/guidance would be appreciated.

 

Regards & TIA,

Ian 

 

[Keesver 20]

You are accessing variable 'Components' as if it where an array, but it is declared like a reference to a TComponent. I think you want to redeclare your function like:

type
TComponentArray = array of TComponent;
function SetDBSessionNames(const ComponentCount: Integer; const Components: TComponentArray; const sSessionName: string): boolean;

 

[Ian Branch 121]

Tks Keesver.  That calms down the function itself, but now the calling function isn't happy

What replaces Components in the calling function?

SetDBSessionNames(ComponentCount, Components, sSessionName);

 

[Renate Schaaf 64]

It looks like you want to use the component list of a TForm, so you should pass that form as a parameter:

 

function SetDBSessionNames(const AForm: TForm; const sSessionName: string): boolean;
begin
  //
  for var i := 0 to AForm.ComponentCount - 1 do
  begin
    //
    if AForm.Components[i] is TEDBSession then (AForm.Components[i] as TEDBSession).SessionName := sSessionName;
..

Then you can call it in the code of a form as

SetDBSessionNames(self, sSessionName);

 

Edited May 3, 2023 by Renate Schaaf

[Ian Branch 121]

Hi Renate,

That looks like a winner but this..

SetDBSessionNames(Self, sSessionName);

Gives me this in this case..

Quote

[dcc32 Error] dmCurrent.pas(821): E2010 Incompatible types: 'TForm' and 'TdmC'

In this case it is a Datamodule the function is being called from.

 

Ian

 

Edit:  Solved - I made it an overload method and created one that use a TDataModule.

Edited May 3, 2023 by Ian Branch

[Uwe Raabe 1891]

Make it TComponent:

function SetDBSessionNames(AContainer: TComponent; const sSessionName: string): boolean;
begin
  //
  for var i := 0 to AContainer.ComponentCount - 1 do
  begin
    //
    var cmp := AContainer.Components[i];
    if cmp is TEDBSession then TEDBSession(cmp).SessionName := sSessionName;
    
    ...

 

[Ian Branch 121]

2 minutes ago, Uwe Raabe said:

Make it TComponent:

Now we're getting fancy.  😉  But I like it.  🙂

 

Edited May 3, 2023 by Ian Branch

[Fr0sT.Brutal 897]

function SetDBSessionNames(const Components: array of TComponent; const sSessionName: string): boolean;

?

[programmerdelphi2k 235]

nevermind... I forgot that BDE dont propagate the "session name" automatically!

Edited May 3, 2023 by programmerdelphi2k

[Remy Lebeau 1263]

10 hours ago, Ian Branch said:

    //
    if (Components[i] is TEDBSession) then (Components[i] as TEDBSession).SessionName := sSessionName;
    //
    if (Components[i] is TEDBDatabase) then (Components[i] as TEDBDatabase).SessionName := sSessionName;
    //
    if (Components[i] is TnlhTable) then (Components[i] as TnlhTable).SessionName := sSessionName;
    //
    if (Components[i] is TnlhQuery) then (Components[i] as TnlhQuery).SessionName := sSessionName;
    //
    if (Components[i] is TnlhScript) then (Components[i] as TnlhScript).SessionName := sSessionName;
    //

 

Wow, that is just screaming for the SessionName to be moved into a common base class, or into a common interface that all of the components implement.

 

If the TEDB... and Tnlh... components are from different libraries, I would simply derive my own classes from them, and define my own interface, eg:

type
  IHaveASessionName = interface
    ['{6ea2f6fe-6b6f-4ea6-a893-12717e562329}']
    function GetTheSessionName: string;
    procedure SetTheSessionName(const Value: string);
    property TheSessionName read GetTheSessionName write SetTheSessionName;
  end;

...

type
  TMyEDBSession = class(TEDBSession, IHaveASessionName)
    function GetTheSessionName;
    procedure SetTheSessionName(const Value: string);  
  end;

function TMyEDBSession.GetTheSessionName;
begin
  Result := SessionName;
end;

procedure TMyEDBSession.SetTheSessionName(const Value: string); 
begin
  SessionName := Value;
end;

// And repeat for TEDBDatabase, TnlhTable, TnlhQuery, TnlhScript, etc...

...

for var i := 0 to ComponentCount - 1 do
begin
  var Intf: IHaveASessionName;
  if Supports(Components[i], IHaveASessionName, Intf) then
    Intf.TheSessionName := sSessionName;
end;

If the components are on DFMs at design-time, you can alternatively use interposer classes in the DFM units, eg:

type
  TEDBSession = class(edbcomps.TEDBSession, IHaveASessionName)
    function GetTheSessionName;
    procedure SetTheSessionName(const Value: string);  
  end;

// etc...

 

Edited May 3, 2023 by Remy Lebeau