New option for args to selection.append

[theJohnnyBrown]

allows selection.append(function). The function is expected to return
a node for each member of the selection.

[mbostock]

Append returns the added nodes; your implementation returns the parent nodes. Also, you can implement this functionality already using select(function). For example:

selection.select(function(d, i) {
  return this.appendChild(…);
});

Or as part of the core library:

diff --git a/src/core/selection-append.js b/src/core/selection-append.js
index 1c57da1..4a1dc20 100644
--- a/src/core/selection-append.js
+++ b/src/core/selection-append.js
@@ -1,7 +1,5 @@
 // TODO append(node)?
-// TODO append(function)?
 d3_selectionPrototype.append = function(name) {
-  name = d3.ns.qualify(name);

   function append() {
     return this.appendChild(document.createElementNS(this.namespaceURI, name));
@@ -11,5 +9,11 @@ d3_selectionPrototype.append = function(name) {
     return this.appendChild(document.createElementNS(name.space, name.local));
   }

-  return this.select(name.local ? appendNS : append);
+  function appendFunction() {
+    return this.appendChild(name.apply(this, arguments));
+  }
+
+  return this.select(typeof name === "function" ? appendFunction
+      : ((name = d3.ns.qualify(name)).local ? appendNS
+      : append));
 };

You haven't said why you want this functionality, so I'd err on the side of leaving it out. If you want to argue for this being useful, feel free to reopen.

Related #4 #311