Is tag a branch?

I've been working with version control software for couple years now. At the beginning it was CVS, now it's mainly SVN. I thought I had a good general understanding of such terms as branch, revision or tag.

Recently I was very surprised when I was asked to commit my changes into a TAG.
So I asked:
- You mean branch?
- No, Tag!
- ???

I always thought that a tag is just a 'marker' that marks a point in a branch and it doesn't branch the code. So what does committing to a tag actually mean? How to commit something to a tag without affecting the branch it was created for?

The answer for those questions can be found in TortoiseSVN documentation explaining what tags and branches actually are from technical perspective:

Tags are typically used to create a static snapshot of the project at a particular stage. As such they not normally used for development - that's what branches are for, which is the reason we recommended the /trunk /branches /tags repository structure in the first place. Working on a tag revision is not a good idea, but because your local files are not write protected there is nothing to stop you doing this by mistake. However, if you try to commit to a path in the repository which contains /tags/, TortoiseSVN will warn you.

Although Tortoise actually allows you to commit into a tag you should never do that! It actually branches the code and makes the code repository messy! After such operations there are actual branches under tags structure. I can't imagine what merging such branched tag with its original branch would actually mean?

But what if you need to add changes to the tagged release (a.g. patches)? Here is the proper way to solve such problem:

It may be that you need to make further changes to a release which you have already tagged. The correct way to handle this is to create a new branch from the tag first and commit the branch. Do your Changes on this branch and then create a new tag from this new branch, e.g. Version_1.0.1.

Now when I understand the problem better I'm just wondering why TortoiseSVN (other tools probably too) allows such operation (with warning). Are there any situations where it would be necessary?

Line numbers in stack trace

When a .net application fails and an exception is thrown you may want to find the reason for such behavior. To identify the code that caused the exception you can examine the stack trace included in your exception. However, the stack trace may not contain line number, which makes the failing code harder to find, especially if you have a lot of code in single methods (not recommended).

Solution:
To ensure that line numbers are included in stack trace you need to deploy .pdb files together with your dll-s. Program database (pdb) files are created when you build your app in Debug mode. You need to copy them to the same directory where dll-s are placed.

Tip: GAC dll-s are stored under folder structure described here

Microsoft Second Shot returns

Those of you who are thinking about getting Microsoft certification may be interested in special offer called Second Shot. It allows you to take a free resit if you happen to fail the exam. Could it be any easier?

The offer is available from January 13, 2010 and it ends on June 30, 2010 so it may be an additional motivation for you.

More details here: http://www.prometric.com/microsoft/ss_mcp.htm

CSS trick for IE

I've just learned a very simple CSS trick that allows you assigning different attribute values if the page is rendered by IE. All you need to do is use '#' and '_' prefixes:

.myTestClass{
   width: 5px;  /* value used by all other browsers */
   #width: 7px; /* value used by IE */
   _width: 9px; /* value used by IE6 and older */
}

I don't think it's a part of the CSS official specification but it works ;)

Expression Web SuperPreview

Recently I've discovered a relatively new product from Microsoft for web development (Asp.Net or PHP) called Expression Web. The product itself looks more or less like Visual Studio with less options available ;)

The functionality that caught my eye was SuperPreview option. It allows developers to render the pages your working on using chosen browser engine within your development area. Available are all popular versions of IE and any other browser installed on your machine. It actually uses the real IE6 engine instead of any emulators. It also allows you to display the same page on multiple layers, each rendered using different engine. This allows you to find the differences much quicker.

You can read about this cool option in this article.

There is also a separate version of SuperPreview which doesn't require Expression Web but it only supports IE. You can download it from here. Here is how my blog looks like when IE6 & IE8 overlay:



PS. I just wish that SuperPreview functionality was available in VS2010. The Expression Web seems as a new product only from marketing perspective. Its designer/developer area offers exactly the same options as in VS (code/design/split views), except the SuperPreview of course. Since VS already supports ASP.NET development, it would be logical to simply add PHP support to it instead of releasing a new product. When I asked tech guys from Microsoft they couldn't really explain this, which I think proves they think the same :)

PHP on Windows

According to Microsoft 70% of PHP developers are working on Windows, although the majority of PHP services are hosted on Linux (in my case this was actually true so maybe they are right about that). This leads to situation where most of the apps are being developed in an environment different than they are deployed to. This is obviously not the best way to that.

Microsoft claims there are 2 main reasons for that:

1. Installation process

Although there are many packages available for one-click installation of all necessary PHP components on Windows (e.g. WAMP) they are all configured to work with Apache server. Although IIS is recommended server to be used for PHP on Windows (to get most of what the system offers), developers are afraid of configuring/using it with their apps.

Microsoft decided to change it by introducing Web Platform Installer. This free tool will download, install and configure all components required to run web applications on your machine for you (both Asp.net and PHP). It also offers installation of popular OpenSource scripts/engines (e.g. for blogs, galleries, etc.) so you can start development faster.

This seems to be a step in a good direction and makes configuration of PHP and IIS easy like never before. However, there are still some some weak points in my opinion:



• Developer is limited to one version of PHP (what if you need to install older version?)


• The installer supports mainly Microsoft technologies e.g. drivers/extensions for MsSql. I haven't seen any option for installation of MySql extensions.


• Some very popular php apps are missing e.g. phpBB (probably MS promotes an equivalent supported by them)




2. Performance

This one is actually more important than installation. Microsoft admits that PHP did not performed well on older versions of IIS. However, together with introduction of IIS7 most of the performance issues should have been resolved. The key aspects for improving performance are:



• Microsoft contributed to creation process of PHP build for Windows e.g. rewritten parts of the code to make better use of the system


• Implementation of FastCGI for Windows (can by installed with Web Platform Installer)


• Windows Cache Extensions for accelerating PHP


• Ability to work in a cloud (thanks to Windows Azure)



I asked the speaker about any reliable benchmarks comparing performance of PHP in Windows vs. Linux environment that would prove that it is worth considering deployment of my PHP apps to Windows. Unfortunately this strongly depends on the app itself so there is no simple answer to that question.

Soo, who's convinced?

BTW. When I asked the Microsoft guy about examples of large, commercial PHP applications deployed on Windows and performing well he answered that there are some but he's not allowed to name them ;)

Code comments generators

Writing comments for your code is not the most interesting part of development. I admit that sometimes it's hard to follow company/project guidelines for code comments in a restrictive way, mostly because the lack of time (I know that's a pure excuse).

Some time ago somebody recommended me to use GhostDoc, which would take care of that for me. Tried it today - simple Shift+Ctrl+D combination and your code is fully commented. Some of the generated comments were even quite descriptive. After quick investigation I found out that all the descriptive comments were copied from base classes (e.g. when method overrides the one in the base class, implements interface member etc). For the new members the comments were generated basing on their names.

In my opinion this could be a handy tool if used correctly i.e. only for generating draft versions that would be corrected/extended manually. However, there is a great danger that most of generated comments would be left unchanged (especially if time is limited). Although it would cause all possible StyleCop rules to pass it would still affect the code quality. I will uninstall it right now because I don't want to be tempted when a deadline is close ;) We don't really need comments that don't introduce any new knowledge.

I'm wondering if there are any positive aspects of using them that I didn't think of? Are there any developers who admit that they're using them and can give some examples proving that this can be very useful?