BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Using TMethod to create a list of procedures/functions (of O          BorlandTalk.com Forum Index -> Delphi OO design View previous topic :: View next topic   Author Message R. Hoek Guest Posted: Mon Oct 06, 2003 8:55 am    Post subject: Using TMethod to create a list of procedures/functions (of O I'm creating a callback manager. Basicly you can register a callback procedure/function with the manager and when the callbackmanager's main callback procedure is called, all registered callbacks will be called sequetially. Now when creating a list of these pointers to object-procedures/functions I typecast these to TMethod. When comparing 2 methods, do I have to compare the Code or Data member of the TMethod record? Or do I have to compare both? I need this to UnRegister the procedure/function, when an Object that registered a procedure/function with the manager is being destroyed. -- Greatings, Ronald Hoek Applicationdevelopper ComponentAgro B.V. Barendrecht Phone. +31-180-621306 Fax. +31-180-611797 E-mail: [email]hoek (AT) componentagro (DOT) nl[/email] <mailto:Amailhoek (AT) componentagro (DOT) nl> http://www.componentagro.nl -- Greatings, Ronald Hoek Applicationdevelopper ComponentAgro B.V. Barendrecht Phone. +31-180-621306 Fax. +31-180-611797 E-mail: [email]hoek (AT) componentagro (DOT) nl[/email] <mailto:Amailhoek (AT) componentagro (DOT) nl> http://www.componentagro.nl Back to top Bryan Crotaz Guest Posted: Mon Oct 06, 2003 5:40 pm    Post subject: Re: Using TMethod to create a list of procedures/functions ( Personally, I would do it with interfaces, and then TInterfaceList does all the work for you. If not, you need to compare both Code and Data of TMethod. Bryan "R. Hoek" <nospam*hoek (AT) componentagro (DOT) nl> wrote Quote: I'm creating a callback manager. Basicly you can register a callback procedure/function with the manager and when the callbackmanager's main callback procedure is called, all registered callbacks will be called sequetially. Now when creating a list of these pointers to object-procedures/functions I typecast these to TMethod. When comparing 2 methods, do I have to compare the Code or Data member of the TMethod record? Or do I have to compare both? I need this to UnRegister the procedure/function, when an Object that registered a procedure/function with the manager is being destroyed. -- Greatings, Ronald Hoek Applicationdevelopper ComponentAgro B.V. Barendrecht Phone. +31-180-621306 Fax. +31-180-611797 E-mail: [email]hoek (AT) componentagro (DOT) nl[/email] http://www.componentagro.nl -- Greatings, Ronald Hoek Applicationdevelopper ComponentAgro B.V. Barendrecht Phone. +31-180-621306 Fax. +31-180-611797 E-mail: [email]hoek (AT) componentagro (DOT) nl[/email] http://www.componentagro.nl Back to top Mauricio I. Magni Guest Posted: Mon Oct 06, 2003 6:27 pm    Post subject: Re: Using TMethod to create a list of procedures/functions ( I compare either Code as Data. This comparison works ok!. A little question, do you use a TMethod array or another structure? Thanks. Mauricio. "R. Hoek" <nospam*hoek (AT) componentagro (DOT) nl> wrote Quote: I'm creating a callback manager. Basicly you can register a callback procedure/function with the manager and when the callbackmanager's main callback procedure is called, all registered callbacks will be called sequetially. Now when creating a list of these pointers to object-procedures/functions I typecast these to TMethod. When comparing 2 methods, do I have to compare the Code or Data member of the TMethod record? Or do I have to compare both? I need this to UnRegister the procedure/function, when an Object that registered a procedure/function with the manager is being destroyed. -- Greatings, Ronald Hoek Applicationdevelopper ComponentAgro B.V. Barendrecht Phone. +31-180-621306 Fax. +31-180-611797 E-mail: [email]hoek (AT) componentagro (DOT) nl[/email] http://www.componentagro.nl -- Greatings, Ronald Hoek Applicationdevelopper ComponentAgro B.V. Barendrecht Phone. +31-180-621306 Fax. +31-180-611797 E-mail: [email]hoek (AT) componentagro (DOT) nl[/email] http://www.componentagro.nl Back to top R. Hoek Guest Posted: Tue Oct 07, 2003 10:10 am    Post subject: Re: Using TMethod to create a list of procedures/functions ( Quote: A little question, do you use a TMethod array or another structure? Well I use TMethode (but it's a record type) -- Greatings, Ronald Hoek Back to top John Elrick Guest Posted: Tue Oct 07, 2003 2:31 pm    Post subject: Re: Using TMethod to create a list of procedures/functions ( "R. Hoek" <nospam*hoek (AT) componentagro (DOT) nl> wrote Quote: I'm creating a callback manager. Basicly you can register a callback procedure/function with the manager and when the callbackmanager's main callback procedure is called, all registered callbacks will be called sequetially. Now when creating a list of these pointers to object-procedures/functions I typecast these to TMethod. When comparing 2 methods, do I have to compare the Code or Data member of the TMethod record? Or do I have to compare both? Well...if the callbacks follow a specific signature: TMyMethodCallback = procedure(const aParam: string) of object; IMethodAdapter = interface procedure execute(const aParam: string); function equals(const aMethodCallback: TMyMethodCallback): boolean; end; TMethodAdapter = class(TInterfacedObject, IMethodAdapter) private FMyMethodCallback: TMyMethodCallback; public constructor create(const aMethodCallback: TMyMethodCallback); procedure execute(const aParam: string); function equals(const aMethodCallback: TMyMethodCallback): boolean; end; ICallbackRegistry = interface procedure register(const aMethodCallback: TMyMethodCallback); procedure unregister(const aMethodCallback: TMyMethodCallback); procedure execute(const aParam: string); end; TCallbackRegistry = class(TInterfacedObject, ICallbackRegistry) ....stuff ommitted, but trivial procedure register(const aMethodCallback: TMyMethodCallback); procedure unregister(const aMethodCallback: TMyMethodCallback); procedure execute(const aParam: string); end; function TMethodAdapter.equals(const aMethodCallback: TMyMethodCallback): boolean; begin result := aMethodCallback = FMyMethodCallback; end; ....and if they don't: TMyMethodCallback1 = procedure(const aParam: string) of object; TMyMethodCallback2 = procedure(const aParam: string; const aInt: integer) of object; IExecuteVisitor = interface procedure callback(const aMethodCallback: TMyMethodCallback1); overload; procedure callback(const aMethodCallback: TMyMethodCallback2); overload; end; IMethodAdapter = interface procedure execute(const aExecuteVisitor: IExecuteVisitor); function equals(const aMethodCallback: TMyMethodCallback1): boolean; overload; function equals(const aMethodCallback: TMyMethodCallback2): boolean; overload; end; HTH John Back to top Ritchie Annand Guest Posted: Fri Oct 10, 2003 1:42 am    Post subject: Re: Using TMethod to create a list of procedures/functions ( In article <3f81b311 (AT) newsgroups (DOT) borland.com>, [email]mmagni (AT) belatrixsf (DOT) com[/email] says... Quote: I compare either Code as Data. This comparison works ok!. A little question, do you use a TMethod array or another structure? Thanks. You really, really should compare BOTH :) Code refers to the method. Data refers to the object. If you compare Code but not Data, you won't be able to tell the difference between the same OnXXX in two different instances of the same class. var AX1, AX2 : TMyClass; begin AX1 := TMyClass.Create; AX2 := TMyClass.Create; CompareCode(AX1.OnMyEvent, AX2.OnMyEvent); If you compare Data but not Code, you won't be able to tell the difference between OnXXX and OnYYY from the same object. var AX1 : TMyClass; begin AX1 := TMyClass.Create; CompareData(AX1.OnMyEvent, AX1.OnMyOtherEvent); You can, with some rather esoteric programming, actually "bind" Code and Data together manually: NOTE: This will NOT work on .NET! (Or at least I'd be really really really surprised if it did ;) procedure CallMe(ACodePointer : Pointer; AMethodObject : TObject); type TPlainMethod = procedure of object; var AMethod : TMethod; ACall : TPlainMethod absolute AMethod; // Makes ACall an alias for // AMethod begin // Bind the method to the object that should run it AMethod.Code := ACodePointer; AMethod.Data := AMethodObject; // Call the method! ACall; end; CallMe(@TMyClass.MyMethod,SomeInstanceOfMyClass); -- Ritchie Annand Senior Software Architect http://www.malibugroup.com http://nimble.nimblebrain.net http://wiki.nimblebrain.net Back to top Bryan Crotaz Guest Posted: Fri Oct 10, 2003 4:17 am    Post subject: Re: Using TMethod to create a list of procedures/functions ( Quote: NOTE: This will NOT work on .NET! (Or at least I'd be really really really surprised if it did ;) procedure CallMe(ACodePointer : Pointer; AMethodObject : TObject); type TPlainMethod = procedure of object; var AMethod : TMethod; ACall : TPlainMethod absolute AMethod; // Makes ACall an alias for // AMethod begin // Bind the method to the object that should run it AMethod.Code := ACodePointer; AMethod.Data := AMethodObject; // Call the method! ACall; end; CallMe(@TMyClass.MyMethod,SomeInstanceOfMyClass); Ye Gods! I would be horrified if this worked in .NET. How many unsafe things are you doing in there. absolute for a start!! I love the idea of absolute, but I've only found one use for it so far, and you've just found another... 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