<p>WARNING: this request may make no sense at all, also my golang syntax may have some errors</p>
<p>OK, let's say I have yaml like this:</p>
<pre><code>one:
Type: circle
Radius: 4
two:
Type: square
Length: 6
three:
Type: square
Length: 2
</code></pre>
<p>And I would like to end up with a Map[string]Shape, Where Shape is an interface that two classes implement: Square and Circle.</p>
<p>Something like this:</p>
<pre><code>type Shape interface {
Render() bool
}
type Shapes Map[string]Shape
type Circle struct {
Radius int `yaml:"Radius"`
}
func (shape Circle) Render() bool { return true }
type Square struct {
Length int `yaml:"Length"`
}
func (shape Square) Render() bool { return true }
</code></pre>
<p>And I want an unmarshalled result of something like this:</p>
<pre><code>Shapes {
"one": Shape( &Circle( Radius:4 ) )
"two": Shape( &Square( Length:6 ) )
"three": Shape( &Square( Length:2 ) )
}
</code></pre>
<p>It occurs to me that I should be able to use an interim handling struct/class, for a marshall method on the map. The interim struct can catch the Type, and then marshall the yaml for just the one map element into the particular class, convert for the interface, and then attach the appropriate struct to the map.</p>
<p>I will use comments to iterate some of the approaches I was thinking of.</p>
<p>[edit: like 9 or 10 edits just to fix some golang, and get the formatting right]</p>
<hr/>**评论：**<br/><br/>jaxxed: <pre><p>It seems that using an interim struct for the purposes of the parsing makes sense.</p>
<pre><code>struct YamlShape {
Type string `yaml:"Type"`
}
</code></pre>
<p>Initially each element of the Yaml map, can be unmarshalled first into the YamlShape, and then the type can be used create the proper Shape object.</p>
<p>I know how to overload the UnMarshall() to get map[string[YamlShapes, but then I don't know how to get access to the initial Yaml for the Shape? </p></pre>mattyw83: <pre><p>You seem to be in a similar situation to this post I did a while back (in json but the ideas are similar) <a href="http://mattyjwilliams.blogspot.co.uk/2013/01/using-go-to-unmarshal-json-lists-with.html" rel="nofollow">http://mattyjwilliams.blogspot.co.uk/2013/01/using-go-to-unmarshal-json-lists-with.html</a></p>
<p>I'd try to start of with very little magic: Just turn the yaml into a map of maps and then iterate over the maps building the shapes as you</p></pre>jaxxed: <pre><p>that seems to make sense. Just unmarshall into interfaces, then read the interface attributes for type.</p>
<p>I'll give it a shot, probably using your first example.</p></pre>mattyw83: <pre><p>Let me know how it goes, happy to take a look at the code</p></pre>
