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One property of computer languages that is important but often seems to be overlooked is how easy it is to refactor programs written in them.

The one example that springs immediately to mind is renaming a class. In C++ this is a bit more difficult than in many languages because the constructors and destructors have the same name as the class, so you have to go and change all of those too. PHP wins here for calling them __construct and __destruct respectively.

If you are in the school of thought that has C++ method definitions in a separate file (e.g. .cpp) to class declarations (.h), you have to go and change things in two different files (even if you're just adding a method that nobody calls yet). If that class implements an COM interface defined by a .idl file then there's yet another thing you need to change.

Python's syntactically-significant whitespace is another winner here because if (for example) you put another statement in an "if" clause that currently only has one statement, you don't have to add braces.

I'm sure there are many other, deeper examples.

Object Oriented Programming is at least as much a state of mind as a set of programming language facilities. When I learnt C++ it was a bit difficult to get used to writing object-oriented programs but now that I've been doing it for many years I can't get used to thinking about my programs any other way.

I was writing some PHP code recently and (not knowing about PHP classes) started writing it in a procedural fashion. After a while I noticed that many of the functions I was writing started to fall naturally into classes (with a first parameter that gave the function context). So it was only natural to re-write it in object-oriented style once I figured out how to do so.

In the process of doing so, I found lots of bugs in my original code (which I had thought was rather nifty). Many functions became much simpler. I also found it was much easier to do various optimizations that would have been very difficult to do without classes (such as minimizing the number of database queries). My code file did become somewhat bigger, but I attribute this to the extra indentation most lines have, and the fact that PHP requires you to write "$this->" everywhere.

I also tried writing a C program (from scratch) for the first time in a very long time a while ago. I found myself using an object-oriented style and implementing vtables as structs.

Given that PHP is designed to be used to write applications that run on web servers, you'd think it would have been designed rather more with security in mind.

In particular, PHP's dynamic typing seems to be a source of security weaknesses. Dynamic typing has advantages in rapid development and code malleability but is not particularly helpful for writing secure code - security is greatly helped by being able to restrict each variable to a specific set of values and having the compiler enforce this.

Similarly with the SQL API - because the interface is all just strings instead of strongly typed objects, SQL injection vulnerabilities becomes all to easy to write.

Variable scope is another one - because there are no variable declarations it's not obvious where variables are introduced, so one could be using variables declared earlier without realizing it (this is why register_globals changed from default-on, to default-off, to deprecated to removed).

Then there are ill-concieved features like magic quotes, and missing features like cryptographically secure random number generation.

A well-designed language for web development would be secure by default when doing the most obvious thing - one shouldn't have to go out of one's way to learn what all the security pitfalls are and have to write to explicitly address each of them (and update your code when the next such pitfall is discovered).

In order to implement Tet4 I learnt two new languages - JavaScript (or JScript, or ECMAScript - the language has a bit of an identity crisis) and PHP. Why PHP? It's installed on my web hosting server and seems to have a huge community of people writing code in it and pre-written scripts. It may not be the ideal language for writing web server apps, but it does seem to be the most well-supported.

JavaScript seems to be a very clean, pretty language. The whole closure thing seemed a bit weird at first but once I understood that "class" is spelled "function" and "public" is spelled "this." I got to rather liking it. I especially like how each scope has access
to the variables from all the outer scopes - that saves a lot of messing about. It's very well integrated with the browser - manipulating the DOM feels very natural and not tacked on.

PHP on the other hand is a bit of a mess. It is as if its designers had a little spinner with markings "C, C++, Perl" which they spun each day to decide what languages features to copy that day. If JavaScript was sent by God, surely PHP was sent by the devil.

W3Schools has been an excellent reference for learning all this.

I have to say though that automatically promoting integers to double-precision floating point numbers on overflow is weird. On IE7, computing the value of 1111111111*1111111111 gives 1234567900987654400 (you can easily see this is wrong because it's even). This caused a rather hard-to-debug problem with my random number generator (which assumed that when multiplying two 32-bit integers together, at least the low 32 bits of the result should be correct). If you're going to automatically promote numbers, at least have the decency to use a multiple-precision integer library - there are lots around.