Storing object properties

[KemBill]

I'm looking for a shorter way to store user preferences, in this exemple I must define a setter to each property in order to save it's value

Code: Pascal  [Select][+][-]

1.   { TSomething }
2.  
3.   TSomething = class(TObject)
4.   private
5.     fSomething: integer;
6.     procedure setSomething(AValue: integer);
7.   public
8.     property Something: integer read fSomething write setSomething;
9.   end;
10.  
11. implementation
12.  
13. { TSomething }
14.  
15. procedure TSomething.setSomething(AValue: integer);
16. begin
17.   if fSomething=AValue then Exit;
18.   fSomething:=AValue;
19.   //Store something into registry or ini file
20. end;
21.  

I Hope that I am understandable (for example in PHP I would have used magic methods __set). Do someone know a better way ?

[Thaddy]

Provided you have generated RTTI (Published property, TComponent, {$M+}, published,not public, the easiest is to use writecomponentresfile and readcomponentresfile and family (TStream).
There are many examples for this, both for Delphi and Freepascal/Lazarus.

Both functions take just a filename and a TComponent as parameters. Those will also read/write the published properties of any children.

[mangakissa]

Code: Pascal  [Select][+][-]

1.  { TSomething }
2.  
3.   TSomething = class(TObject)
4.   private
5.     fSomething: integer;
6.     procedure setSomething(AValue: integer);
7.   public
8.     procedure savePreference(const aRef : string; const aValue : integer);
9.  
10.     property Something: integer read fSomething;
11.   end;
12.  
13. implementation
14.  
15. { TSomething }
16.  
17. procedure TSomething.savePreference(const aRef : string; const aValue : integer);
18. begin
19.   //write your value to registry / ini
20.   case aRef of
21.     'something' : fSomething := aValue;
22.   end;
23. end;
24.  

[Thaddy]

@mangakissa,
That won't do. My pointer is a generic solution and way simpler to maintain.
It was also designed for the purpose.

[KemBill]

@Thaddy, I forgot to say that i need to store values in a human readable format 

@mangakissa
you make property read only and the only way to update it is to use savePreference. the main problem behind this, is that you need to write a proc for every type

[Thaddy]

@Thaddy, I forgot to say that i need to store values in a human readable format 

It is human readable: it is XML like, not a binary format, don't worry.... Those were the olden days...

[Edson]

I use my library: https://github.com/t-edson/MiConfig

Just associate variables to an IniFile:

Code: Pascal  [Select][+][-]

1. iniFile.Asoc_Str('MyText', @MyText, 'default');
2. iniFile.Asoc_Int('MyNumber', @MyNumber, -1);
3. ...
4.  

Then you can move values to file, and vice versa:

Code: Pascal  [Select][+][-]

1. iniFile.FileToProperties;
2. iniFile.PropertiesToFile;
3. ...
4.  

[Thaddy]

@Edson

WHY? There is a standard for this as I pointed out. AND it is just XML?

[taazz]

@Edson

WHY? There is a standard for this as I pointed out. AND it is just XML?

nope its plain old text files, oh wait its plain old ini files oh wait its plain old JSON files oh wait its a key value store oh wait that windows registry well depends on the OS you are using I guess just don't waste the end users disk space with garbage (XML).

[Thaddy]

@Edson

WHY? There is a standard for this as I pointed out. AND it is just XML?

nope its plain old text files, oh wait its plain old ini files oh wait its plain old JSON files oh wait its a key value store oh wait that windows registry well depends on the OS you are using I guess just don't waste the end users disk space with garbage (XML).

I am not discussing the format, but it it is human readable and editable in any simple editor. Even edlin..... see https://en.wikipedia.org/wiki/Edlin
Perfect forms editor... better than "copy con.... ctrr-z" don't you think?

[taazz]

@Edson

WHY? There is a standard for this as I pointed out. AND it is just XML?

nope its plain old text files, oh wait its plain old ini files oh wait its plain old JSON files oh wait its a key value store oh wait that windows registry well depends on the OS you are using I guess just don't waste the end users disk space with garbage (XML).

I am not discussing the format, but it it is human readable and editable in any simple editor. Even edlin..... see https://en.wikipedia.org/wiki/Edlin
Perfect forms editor... better than "copy con.... ctrr-z" don't you think?

well I never liked edlin so I only used it once, I used "copy con " extensively for admin scripts even after I discovered the norton/midnight commander and its build in editor.  I would stick with ini files for readable config files.

[Edson]

@Edson
WHY? There is a standard for this as I pointed out. AND it is just XML?

This library not only associate:

Disk <---> Properties

It's intended to achieve a real association between:

Disk <---> Properties <---> Visual Component

So it can help on creating setting dialogs. An association for a property, a control, and disk can be done in one line of code, including range checking, default value.

And the file can be INI or XML.

Is there some standar way to do the same?

[molly]

Is there some standar way to do the same?

It probably won't do as a standard way as there are many roads that leads to Rome but have a look at TXMLPropStorage and/or TIniPropStorage

[Edson]

It probably won't do as a standard way as there are many roads that leads to Rome but have a look at TXMLPropStorage and/or TIniPropStorage

They only do:  Disk <---> Properties

[molly]

They only do:  Disk <---> Properties

And from properties you can go to variables. Although that is a bit redundant. Seems you are not aware of TDataModule and storing your (global) settings in there using properties ? Whether or not you associate those properties to anything else is up to yourself.

edit:

Disk <---> Properties <---> Visual Component
So it can help on creating setting dialogs. An association for a property, a control, and disk can be done in one line of code, including range checking, default value.

XMLPorpstorage by default does:
Disk <---> Properties of any (visual) Component