[configuration] Locale aware configuration

[Alex Coyle <ac...@f2s.com>]

Hi there,

Some months ago there was a discussion regarding a decorator for a 
configuration, 'ConfigurationLocaleAware', that would provide a locale 
sensitive API to get properties. At that time a reference was made to the 
'Scarab' project to show how it might be implemented. I'm interested in 
creating such a decorator, but I couldn't find much Scarab information to 
see how it was tackled there.

Any pointers? I've had a stab at a design, but currently I can't find a way 
to avoid using 'instanceof' to find out the type of configuration my 
decorator is wrapping, e.g. AbstractFileConfiguration, 
DatabaseConfiguration, JNDIConfiguration. This is necessary to create a new 
configuration based on the wrapped one, with a 'suffix' for locale sensitive 
lookups. This approach doesn't cater for a CompositeConfiguration either - 
the only way I can see to do that is provide a locale aware implementation 
of a composite configuration.

Thanks

Alex.




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Re: [configuration] Locale aware configuration

[Oliver Heger <ol...@t-online.de>]

Alex Coyle wrote:

> Hi there,
>
> Some months ago there was a discussion regarding a decorator for a 
> configuration, 'ConfigurationLocaleAware', that would provide a locale 
> sensitive API to get properties. At that time a reference was made to 
> the 'Scarab' project to show how it might be implemented. I'm 
> interested in creating such a decorator, but I couldn't find much 
> Scarab information to see how it was tackled there.
>
> Any pointers? I've had a stab at a design, but currently I can't find 
> a way to avoid using 'instanceof' to find out the type of 
> configuration my decorator is wrapping, e.g. 
> AbstractFileConfiguration, DatabaseConfiguration, JNDIConfiguration. 
> This is necessary to create a new configuration based on the wrapped 
> one, with a 'suffix' for locale sensitive lookups. This approach 
> doesn't cater for a CompositeConfiguration either - the only way I can 
> see to do that is provide a locale aware implementation of a composite 
> configuration.
>
> Thanks
>
> Alex.
>
I was not involved in the discussion you mentioned and don't remeber the 
details.

Not sure if I fully understand what you are doing and what you mean by 
"'suffix' for locale sensitive lookups. How does your locale sensitive 
configuration look like? Does it implement the Configuration interface?

A naive approach would be to have a class LocaleConfiguration that 
defines a map for the supported locales. This map would store locales as 
keys and corresponding Configuration objects as values. This class would 
not implement the Configuration interface because all getter methods 
would need an additional argument for the Locale. This could roughly 
look as follows (with getProperty() used as example):

public class LocaleConfiguration
{
    private Map locales;

    Configuration getConfigForLocale(Locale locale)
    {
        Configuration result = (Configuration) locales.get(locale);
        // deal with null values, e.g. use a default locale
        return result;
    }

    public Object getProperty(String key, Locale locale)
    {
        return getConfigForLocale(locale).getProperty(key);
    }
    ...
}

You seem to do something different, do you?

Oliver

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