clearer error when forgeting to provide a value for a placeholder

cbovar · cbovar · commit fbd12533cb9f · 2018-05-12T09:32:41.000+08:00
diff --git a/src/ConvNetSharp.Flow/Session.cs b/src/ConvNetSharp.Flow/Session.cs
@@ -126,7 +126,12 @@ public void UpdatePlaceHolder(Op<T> fun, Dictionary<string, Volume<T>> dictionar
             {
                 if (op is PlaceHolder<T> placeHolder)
                 {
-                    placeHolder.SetValue(dictionary[placeHolder.Name]);
+                    if (!dictionary.TryGetValue(placeHolder.Name, out var volume))
+                    {
+                        throw new Exception($"Cannot find key '{placeHolder.Name}' in the provided dictionary");
+                    }
+                   
+                    placeHolder.SetValue(volume);
                 }
 
                 if (op is Variable<T> variable && variable.IsLearnable)

Original file line number	Diff line number	Diff line change
`@@ -126,7 +126,12 @@ public void UpdatePlaceHolder(Op<T> fun, Dictionary<string, Volume<T>> dictionar`
`126`	`126`	`{`
`127`	`127`	`if (op is PlaceHolder<T> placeHolder)`
`128`	`128`	`{`
`129`		`- placeHolder.SetValue(dictionary[placeHolder.Name]);`
	`129`	`+ if (!dictionary.TryGetValue(placeHolder.Name, out var volume))`
	`130`	`+ {`
	`131`	`+ throw new Exception($"Cannot find key '{placeHolder.Name}' in the provided dictionary");`
	`132`	`+ }`
	`133`	`+`
	`134`	`+ placeHolder.SetValue(volume);`
`130`	`135`	`}`
`131`	`136`
`132`	`137`	`if (op is Variable<T> variable && variable.IsLearnable)`