C++ Design pattern

[rian]

Hi Guys,

I am working on a task to write a data extractor from a database to a flat delimited file.
The trick is that the output format although is fixed (i.e. what columns I need) , it is subject to change in the future (as with any software system requirements :-) )

I can write a program and make the fields configurable via a input file or hold it in a table etc, but was wondering if there is any standard C++ design pattern that can address this situation.

I looked at MVC/Observer but looks like what I need is the reverse where my view can change, but my model remains the same.

Is Mediator pattern worth a shot?

Let me mention that my Model (i.e. Database / table / columns) are pretty stable. It is just that the output is subjected to change in the future.

Thanks in advance

Rian

[kbw]

I need is the reverse where my view can change, but my model remains the same.

Are you sure?

[rian]

Yes, Atleast for now my output is the changeable component in the extract and my database table / columns are stable.

[kbw]

Where does "your output" get its information?

[rian]

The output value will be from the database and whether to include the column in my output can be decided by say a config file.

What i would like is to change the config file to add a new column to output, but shouldn't need to change the program.

Thanks

Ri

[kbw]

The config file is part of your model.

[JLBorges]

Either the strategy pattern http://sourcemaking.com/design_patterns/strategy

or the template method pattern http://sourcemaking.com/design_patterns/template_method

(or perhaps both a la streams, locales and facets) seem appropriate.