[OpenLayers-Users] Overwriting OL classes

[Christopher Schmidt]

On Mon, Apr 06, 2009 at 08:40:05AM -0700, Gregor at HostGIS wrote:
> Heidt, Christopher M. wrote:
> > Is there a prefered method for overwriting an ol class?
> > I want to use my own custom cluster strategy,
> > so is it as easy as including my own js file after i include ol?
> 
> 1) Get your own copy of OL and use that, instead of using the hosted 
> copy. Change your app to use it.
> 
> 2) Go into the source and hack away.

Generally, I don't recommend this, because when you want to upgrade,
you're screwed.

Things that I do:

 * Create subclasses: If you want to override the onClusterFoo method of
    cluster, you can do:

   MyCluster = OpenLayers.Class(OpenLayers.Strategy.Cluster, {
    onClusterFoo: function() { 
     // do stuff
    }
   });
 
 * Override methods:

    OpenLayers.Strategy.Cluster.prototype.onClusterFoo = function() { }

 * Pass in custom functions to options:

    var myc = new OpenLayers.Control.Strategy({onClusterFoo: function() { } });

All of these are reasonable ways to make changes without 'breaking' the
existing code. When you upgrade OL, you'll still have to update your
code, but at least you have a nice clean source of 'diffs', practically
speaking, and don't have to deal with SVN's messy merges.

-- Chris

> 3) Go into the ol build/ directory and "python build.py" to merge all of 
> the changes and build a compressed copy of OL. Believe me, running OL 
> with hundreds of uncompressed files is not fun.
> 
> 4) Copy the resulting build/OpenLayers.js into the OL directory, 
> overwriting the old one.
> 
> -- 
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-- 
Christopher Schmidt
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