[SOLVED] Use Create (class) with parameters and overload
lazarus / 21-General

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Hansvb · 2021-08-02 08:40

hi,

This is not allowed ?
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i constructor
Create(ConnectionName, Password, SchemaName, DatabaseName : String);
begin  inherited;  --> Goes wrong:
 oracleconnectionmaintain.pas(107,12) Error: Wrong number of
parameters specified for call to "Create"end;
My base class is:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i unit
SQliteConnection; {$mode objfpc}{$H+} interface uses  Classes,
SysUtils, Settings, SQLite3Conn, SQLDB; type   { TSQliteConnection }  
TSQliteConnection = class(TObject)     private     
FAppDatabaseFolder, FAppDatabaseFile : String;       function
GetAppDatabaseFile: String;      function GetAppDatabaseFolder:
String;      procedure SetAppDatabaseFile(AValue: String);     
procedure SetAppDatabaseFolder(AValue: String);      protected     
SQLite3Conn: TSQLite3Connection;      SQLTransaction:
TSQLTransaction;     public      constructor Create; overload;     
destructor Destroy; override;      property AppDatabaseFolder : String
Read GetAppDatabaseFolder Write SetAppDatabaseFolder;      property
AppDatabaseFile : String  Read GetAppDatabaseFile Write
SetAppDatabaseFile;   end; implementation { TSQliteConnection
} {%region Properties}...{%endregion Properties} constructor
TSQliteConnection.Create;begin  inherited;  AppDatabaseFolder :=
ExtractFilePath(ParamStr(0));  AppDatabaseFile := AppDatabaseFolder +
Settings.DatabaseFolder + PathDelim + Settings.DatabaseName;  
SQLite3Conn := TSQLite3Connection.Create(nil);  SQLTransaction :=
TSQLTransaction.Create(nil);   SQLite3Conn.Transaction :=
SQLTransaction;  SQLTransaction.DataBase :=
SQLite3Conn; end; destructor TSQliteConnection.Destroy;begin  if
assigned(SQLite3Conn) then SQLite3Conn.Free;  if
assigned(SQLTransaction) then SQLTransaction.Free;   inherited
Destroy;end; end.

The class where the create goes wrong has:


Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses ...,
SQliteConnection; type  { TOraConmaintain }  TOraConmaintain =
class(TSQliteConnection)   ...public  //constructor Create; overload; 
constructor Create(ConnectionName, Password, SchemaName, DatabaseName
: String);   overload;          ... constructor
TOraConmaintain.Create(ConnectionName, Password, SchemaName, 
DatabaseName: String); begin  inherited;  --> Goes wrong:
 oracleconnectionmaintain.pas(107,12) Error: Wrong number of
parameters specified for call to "Create"   OraConnectionName :=
ConnectionName;  OraSchemaName := SchemaName;  OraPassword :=
Password;  OraDatabaseName := DatabaseName;end;     
When i remove "inherited;" then the program compiles but goes wrong
when i execute it. I think that is because the create in the base
class is not executed.

Is it not possible to use overload on a create with parameters?

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Bart · 2021-08-02 08:50

Does this work in the overloaded constructor?

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i   inherited
Create;  ...
Bart

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lucamar · 2021-08-02 08:57

When you use only "inherited" it will look for a method with the same
signature than the current one, which in this case doesn't exists.
Instead it finds the original Create and tries to see if it can be
called with the parameters of the current one, which it can't; hence
the error.

Specifying which inherited method you want, as Bart showed,
circumvents this and calls the exact method you want.

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Hansvb · 2021-08-02 09:03

QuoteWhen you use only "inherited" it will look for a method with the
same signature than the current one, which in this case doesn't
exists. Instead it finds the original Create and tries to see if it
can be called with the parameters of the current one, which it can't;
hence the error.
I saw this just after posting my question. In the message window i saw
an other error which pointed to the create function of my base class.
Good to know.

Adding
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i inherited
Create;
This does the trick. No errors when compiling and no errors when
executing.

Thanks!