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[nycphp-talk] Getting Closure - on PHP Closures and 5.3

Greg Rundlett (freephile) greg at freephile.com
Fri Jul 16 21:20:38 EDT 2010


OK, I'll bite... is the code somewhere so I can see how easy that is?
 Didn't find it on iTunes nor the (http://www.yogalocal.com/) website.

Greg Rundlett




On Fri, Jul 16, 2010 at 8:29 PM, Edward Potter <edwardpotter at gmail.com>wrote:

> >>> Given an array of businesses with latitude/longitude coordinates, and
> the user's location, sort the array of businesses by closest to the user.
>
> A slight language digression:
>
> Oh my, if you saw how easy that was to do on an iPhone in ObjC
> (hundreds of locations). And then visualize it all on a google map
> with a detail view of everyone of those locations. With data updated
> in real-time. With a 5,000 mile server round trip. And do it all in a
> blink of the eye.
> (plus you get to talk to 4 orbiting satellites at the same time).  Yummy!
> :-)
>
> Code in action here: (dropping, sorted pins by user location 1/2 way
> through).
> http://www.youtube.com/watch?v=krF9IUyF3Rw
>
>
> On Fri, Jul 16, 2010 at 4:36 PM, John Campbell <jcampbell1 at gmail.com>
> wrote:
> > On Fri, Jul 16, 2010 at 2:48 PM, Hans Zaunere <lists at zaunere.com> wrote:
> >> Closures - great for Javascript, but for PHP?  In a non-callback-centric
> >> synchronous language such as PHP, what else can we use this "syntactic
> >> sugar" for?  How are people using them and what can we gain from them?
>  And,
> >> the hell with code reuse?
> >
> > I have a favorite problem, that is hard/ugly to solve without closures:
> >
> > Given an array of businesses with latitude/longitude coordinates, and
> > the user's location, sort the array of businesses by closest to the
> > user.
> >
> > so you have:
> >
> > $stores = array(
> >  array('name' => 'Pet Smart', 'lat'=>24.12, 'lon' => 54.23),
> >  array('name' => 'Cats and Critter', 'lat'=>24.19, 'lon' => 54.32),
> >  array('name' => 'Snakes and such', 'lat'=>24.45, 'lon' => 53.35),
> >  array('name' => 'Lots of llams', 'lat'=>24.46, 'lon' => 54.97));
> >
> > $user_location = array('lat'=> 24.45, 'lon' => 54.96);
> >
> > // Solution using closures
> >
> > // geo sort.
> > function sort_by_closest(&$points,$location) {
> >  usort($points, function($a,$b) use($location) {
> >    return distance($a,$location) > distance($b,$location);
> >  });
> > }
> >
> > // geo distance using sperical law of cosines.
> > function distance($a,$b) {
> >        $R = 6371; // km
> >        $d2r = pi() / 180;
> >        return acos(sin($a['lat']*$d2r)*sin($b['lat']*$d2r) +
> >                          cos($a['lat']*$d2r)*cos($b['lat']*$d2r) *
> >                          cos($b['lon']*$d2r-$a['lon']*$d2r)) * $R;
> > }
> >
> > print_r($stores);
> > sort_by_closest($stores,$user_location);
> > print_r($stores);
> >
> >
> > -John
> > _______________________________________________
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> >
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> >
>
>
>
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