I know I'm a bit late to this thread, but I figured I'd chime in anyway.
Why are the hints dissociated from the classes that use them? Any why
have we bastardized the AWT class RenderingHints with things that have
nothing to do with rendering? Also, forcing implementers to reference
some other class that contains final static attributes that might or
might not be relevant just feels mean.
Since in this case we are demanding that users of Foo have a
FilterFactory, but some users just don't care, I would implement it as
follows:
class Foo {
FilterFactory filterFactory;
Foo( FilterFactory input ) {
filterFactory = (input == null) ?
FilterFactoryFinder.findFilterFactory(null) : input;
}
}
class FilterFactoryFinder {
// public static final attributes...
static public FilterFactory findFilterFactory(Collection hints){
FilterFactory result = null;
if((hints != null){
// Iterate through hints and populate result if possible
}
if(result == null){
// assign default
}
return result;
}
}
This way the user has access to whatever they need to do their job, but
nothing more. It also prevents the inevitable NullPointerException
caused by the exceptionally lazy user.
[EMAIL PROTECTED] wrote:
Date: Thu, 12 Oct 2006 14:49:33 -0400
From: Martin Desruisseaux <[EMAIL PROTECTED]>
Subject: Re: [Geotools-devel] Factories: a proposal
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Justin Deoliveira a ?crit :
So I think code that does this:
class Foo {
FilterFactory filterFactory;
Foo() {
filterFactory = FilterFactoryFinder.findFilterFactory();
}
}
should do this.
class Foo {
FilterFactory filterFactory;
Foo( FilterFactory filterFactory ) {
this.filterFactory = filterFactory;
}
}
The alternative that I was talking about (as used in modules that uses correctly
the hints) is:
class Foo {
FilterFactory filterFactory;
Foo(Hints hints) {
filterFactory = FilterFactoryFinder.findFilterFactory(hints);
}
}
which leads to exactly the same result, with more flexibility (null hints for
default, LENIENT_DATUM_SHIFT, FORCE_LONGITUDE_FIRST_AXIS_ORDER, etc). However
one approach doesn't exclude the other. Both can live in parallel; Hints can
actually be considered as an other flavor of constructor injection. More
complete example:
class Foo {
FilterFactory filterFactory;
Foo() {
this((Hints) null);
}
Foo(Hints hints) {
this(FilterFactoryFinder.findFilterFactory(hints));
}
Foo(FilterFactory filterFactory) {
this.filterFactory = filterFactory;
}
}
Martin
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email;internet:[EMAIL PROTECTED]
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