In a new post to his site Christian Weiske shares his interaction with the Open Source group at Apple concerning his Structures_Graph PEAR package. While they were interested in the package and its functionality but with one issue.

Fact is that Structures_Graph is used in the PEAR installer, which is shipped as part of OSX's PHP packages. Apple simply wanted to continue their current setup without changing anything

Unfortunately, Apple had issues with the package being under the LGPLv3 license. They had a concern that, in certain circumstances, the license could allow the owner access to other potentially sensitive information from the user. He lists out his options - bascially either changing the license, asking Apple for compensation or just tell them "no". Unfortunately, if they decide that having it under that license isn't acecptable, they may drop PEAR all together (as the package is a part of the installer itself).

The MyBuilder.com Tech blog has a tutorial posted showing you how to work with binary trees in PHP, specifically how to perform insertion, removal and inversion operations on their data.

Recently Max Howell (creator of Homebrew) posted an interesting tweet in regard to Google's interview process. In this tweet he mentioned how one of the proposed questions was to white-board a solution to invert a binary tree. Over the past couple of years I have been interested in exploring fundamental Computer Science data-structures and algorithms. As a result, I thought it would be interesting to explore this structure and associated operations in more depth - using immutable and mutable PHP implementations to clearly highlight the benefits garnered from each approach.

He starts with a brief definition of what a binary search tree is just to be sure everyone is on the same page. He then gets into the code to represent a Node, a simple class that has a value and "left" and "right" variables to contain each of the possible two child nodes. He then goes through each of the operations (insertion, removal and inversion) showing code examples for both mutable and immutable methods.