Category: cs & it

engineering dogmas

Published: | Categories: cs & it

ver the years in our software community, I’ve seen a lot of dogmas, myths and lies that spread like ‘cholera’. That only reflects the fact that many programmers just repeat like parrots what they ‘learned’ from school, news, books… without their own justification, and to some extent, reflect their lacking of experiences. A good engineer should, at least, have some abilities to judge the pros and cons, weak points and strong points, when to use, and when not to use a method, a language or a technology.

Design first, then code!

The principle is, in general, not wrong. However, pragmatically, a software’s final structure, architecture… is not achievable as product of an immediate thought or a single design cycle. In most cases, the “first design” is certainly not the correct one. It’s not in a deterministic process that we can build software, complex product would always requires a lot of trial and fail. And from my experiences, good designs are sustainable solutions after a tedious process of experiments to eliminate wrong directions. We need coders of strong analysis and experimental skills rather than the “evangelic designers”!

Where are the documents?

We are going to make clear distinction: do we need coders who really understand what they are doing, or we just need some paper to present to customers? In countless cases did I see that coders do not understanding what they are doing: they don’t understand a feature, they don’t know how to archive that, they are unable to judge the pros and cons, they just mechanically copy and paste code from somewhere. Documents only provide rough, general views on the matters. If you’re going to mention about a static-web-page project, I would agree that document is something. But if you’re mentioning system programming, it’s the code that is the document!

Poor skills and wrong knowledges

This is simply put: countless! Just to name a few:

Poor skills: once, a coder being asked to fix a “null pointer exception”. What he did is adding a “if (pointer != NULL)” line into the code. It’s not fixing, it’s just hiding, fixing is find out why the pointer is NULL, not prevent it from being executed! Another time, another coder, getting frustrated under a crash situation, place a “try… catch” around the buggy code segment. This is again, not fixing, with this way of hiding, we’re just going to accumulate faultinesses until the software crashes silently for no reasons!

Object oriented programming rules: OOP is more beautiful in theory than in practice. OOP provides a nice way for modeling, but it come at costs: bloating code. It is not until the project grows above 1M LOC that OOP become a burden, that we would need to do the “functional decomposition” optimization tasks. It’s the execution (functional) tree that decides performance, not the inheritance tree that obscures runtime characteristics!

Design pattern rules: this is again, not true! I agree that patterns reflect some good coding practices, but software could never be built from the so call “patterns” (there hasn’t been any such proven process). I really don’t understand what is a “singleton” if it’s essentially (in C/C++ syntax) a static variable, I also don’t understand what we need from a “factory” if it’s essentially a “switch… case” structure!?

Management myths

Managers tend to forget what they’d learned when they were coders. There’re lots of myths in software management, just some examples:

  • Software people is of a same type and the same background.

  • We already have a book that’s full of standards and procedures for building software. That provide out people with everything they need to know!

  • If we get behind schedule, we can add more programmers and catch up.

  • Project requirements continually change, but change can be easily accommodated because software is flexible.

There have been extensive criticisms on various OOP models and OOP implementations (Java, C#, C++, MFC, Objective C, glib…) The AntiPatterns wiki and many other authors provide good anti-examples on the uses of patterns!

Linus Torvalds, being criticised: “the kernel has no obvious design”, had replied: “Linux is evolution, not intelligent designs”! The same applied for similarly complex projects!

Document is for understanding, but is not the understanding itself.

Software project management is the domain of vast diversity! No simple rules applied to a software process!

Win vs. Mac font rendering (and the way for Linux)

Published: | Categories: computer-graphics, cs & it, linux, mac-ios
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We could easily see the very poor font rendering quality of Windows right on Windows itself using Safari. Safari has different smoothing modes (image above) and another mode named “Windows’ standard” (image below)


Differences between font rendering on Ubuntu (above) and Windows (below).

everal years ago, on earlier versions of Fedora, Ubuntu… font rendering is just a crap! Many people would find Windows better at text rasterization, and both are far inferior compared to Mac. In latest versions of Linux desktop, things are much improved, while Windows (Vista, Win7) is still much lagging behind, Linux made bold advances from lessons learned from both Win and Mac!

Novice users on Windows would find its text sharper, clearer and easier to read, while Mac’s one is a bit blurry! That is because Mac and Win have different origins and targets! Apple has deep legacy in graphics designs and desktop publishing, its algorithms try to preserve the nature of typefaces as much as possible, which implement true sub-pixel rendering aiming at high-resolution output devices. Meanwhile, Win sticks to pixel unit and aims at low-resolution device (like computer screen which usually less than 100 dpi in resolution).

The consequence is that while Win’s text look sharper and clearer on screen, it would turn into a whole crap when come to printing, where Mac’s publishing products are closer to its screen look! Even worse, Windows text rendering solutions are just suitable for simple typefaces, when complex, high-quality font is needed, the output is usually very poor due to various wrong implementations in hinting, anti-aliasing, kerning algorithms. This paper (2007) addresses in details many Microsoft’s implementation problems, and suggest the correct ways for text rasterization, resulting in a now-much-better Linux desktop!

(If you’re using a Mac or a Linux desktop, you would see this blog text in VN URW Gothic L, a aesthetically fine font. Windows readers would only see the text in Arial, as I have to turn off font embedding for Windows due to its very poor presentation.)

Update, Feb, 20th, 2011

The font used now is Tex Gyre Adventor, an enhanced font based on URW Gothic L, you can see the hinting is quite better, especially for Vietnamese text. The trade – off is that file size is much larger, almost triple the URW Gothic L’s size.

career’s funs – 7

Published: | Categories: cs & it

If programming languages are cutleries, still some high respect for Ruby… My experience is that if some languages or technologies come with much bells and whistles, noone would mention about them in the next few years. I just need to keep with me a katana!

here are two ways of constructing a software design. One way is to make it so simple that there are obviously no deficiencies. And the other way is to make it so complicated that there are no obvious deficiencies. (Charles Antony Richard Hoare)

A good programmer is someone who looks both ways before crossing a one-way street. (Doug Linder)

Being abstract is something profoundly different from being vague… The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise. (Edsger Dijkstra)

It should be noted that no ethically-trained software engineer would ever consent to write a DestroyBaghdad procedure. Basic professional ethics would instead require him to write a DestroyCity procedure, to which Baghdad could be given as a parameter. (Nathaniel S. Borenstein)

Measuring programming progress by lines of code is like measuring aircraft building progress by weight. (Bill Gates)

There are only two kinds of programming languages: those people always bitch about and those nobody uses. (Bjarne Stroustrup)

The C programming language, a language which combines the flexibility of assembly language with the power of assembly language. (unknown)

The last good thing written in C# was Beethoven’s Moonlight Sonata. (unknown)

The problem with using C++ … is that there’s already a strong tendency in the language to require you to know everything before you can do anything. (Larry Wall)

A system composed of 100,000 lines of C++ is not be sneezed at… The real test of OOP will come when systems of 1 to 10 million lines of code are developed. (Ed Yourdon)

Computer language design is just like a stroll in the park. Jurassic Park, that is. (Larry Wall)

3d particles

Published: | Categories: computer-graphics, cs & it
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ome funs with 3D effects. Just some years ago, rendering 3D particles like water, smoke, fire, fog… was an extremely hard task. I remember how struggling it was for me to build 3D models for a waterfall (with moving water) or a shouting-crowd stadium. It’s enjoyable to see how graphics has advanced in the past few years, these effects are now easily achievable.

Video above: the classical Utah teapot with steam coming out from its spout, rendered with Panda3D, the well-known open-source game engine originally released by Disney, which has a feature-rich C++ core with Python scripting for application development.

basic algorithms

Published: | Categories: computer-graphics, cs & it, literature

The book is my primary source of interest while being a freshman, which presents a wide range of algorithms in a very coherent and systematic way. I remember “rescuing” this hard-copy from a Fahasa‘s junk pile for about 4 USD, which from that time on became a student’s most precious thing! You can read the soft-copy here.

his is among the subjects I was very fascinated the early years at university: algorithms, graph theory, geometry, image processing… I was not quite good at “symbolic” math (like algebra), but “visual” math offered me much inspiration. The thing I would remember most is Robert Sedgewick‘s Algorithms, a book that I’ve read through over and over again many many times. It is indeed the most important Computer Science textbook that beginners MUST read until today.

The Java applet below is “refurbished” from the code I wrote the first year at college, which visualizes the nature of different sorting algorithms (original code was written in Borland C++ 3.1 with BGI – Borland Graphics Interface). This is among my various attempts to visualize the knowledge collected from the book, which had taught me that even a simple thing like “bubble sort” is not that “very simple”! Let select an algorithm in the dropdown list and click ‘Start’ and see the differences!

My visualizations above are very early (1997), much prior to those demonstrations on wiki. Later on, I’d learned that the author R.Sedgewick put a great emphasis on algorithms’ visualizing himself, his work used PostScript. Many new ways of visualization are really impressive and easy to understand, such as this (using JavaScript).

I started with with C/C++ at school, then continue with C/C++, Java, Design Patterns… on various projects. Later I abandoned Design Patterns (and Java), then I abandoned C++. To me there’s no Design Patterns, there’s only data structures and algorithms! Would write another post on the bloating and non-sense usages of Design Patterns later on!

It seems that most software engineers today lack fundamental knowledges and skills. It’s quite apparent that you could not rely on a guy talking about architecture, GoF’s design patterns… all the time but can not state the algorithmic differences between a DFS (depth first search) and a BFS (breadth first search).

3d graphical user interface

Published: | Categories: computer-graphics, cs & it, linux
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The code is written in C++ base on Clutter 1.2.4 library. It shows basic widgets: tabbed container, scrolling container, list box, combo box, check box, edit box, button, label, radio button…

his is my personal project in which I tried to evaluate some new ideas and concepts in using 3D techniques for GUI (Graphical User Interface). It’s quite tiny indeed (about 6000 LOC – line of code), all written by myself in about a month (mostly in my free times at weekends). So please don’t blame me on some un-completed or un-polished features, they are just for testing the ideas only. I would try to examine the trend of applying 3D graphics to GUI, but first, let have a look at the video below.

1.   The first thing to consider is not 3D engines or hardwares, it is about usability. Many traditional (2D) GUI out there are already complex and obstructive. GUI is about information presentation and presentation should be really simple and clear so that even my grand mother can understand and use. I’ve been seeking, trying to explore many new ways invented to represent information in 3D (or 2.5D) space, and I could say only a very very small percent of them could make a usable value. Users have long been familiar with 2D, and yet 3D hasn’t been very much persuasive.

2.   3D hardwares can be categorized into 3 groups (as listed on the left), and the 3D engine can be configured to off-load calculations to hardware. With the 1st type of device, only bitmap operations could be off-loaded. With the 2nd type of device, many drawing operations (the path_xxx functions) can be off-loaded. The 3rd type of hardware is most valuable since we can have its finish for ourselves a lot of work.

It’s important to understand the target device our software stack would be running on. If it is an out-date machine with just some blitters, we should use paint-like (aka: bitmaps) operations, while on most modern PC, draw-like (aka: 2D vector) operations are more encouraging. While bitmaps may offer nicer and more customizable GUI, the cons is it lacks the scalable ability that vector has.

3.   The last is about software implementation. Many of the graphics concepts are first introduced in software, which then embedded to hardware, which then standardized by software (like OpenGL or DirectX) again. Thus, many elements of a graphics pipeline is the production of a long history of interactive evolution. A graphics pipleline is not a general framework, it depends on very detailed, in-depth techniques to be operational in real-world application.

Game & graphics are the domains where most formal software methods would easily failed. 3D graphics developers should have good knowledge on graphics in general (bitmap and vector drawing), geometry, linear algebra & discrete maths, deep understanding on data-structures and algorithms… are strong pluses, advanced tips & tricks in coding and optimization is a must (game & graphics programming has always been a hell of tricks from the age of dawn) and finally good understanding on 3D techniques (model, scenegraph, projecting, shading, clipping, lighting, effects…)

3d

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e are building something like this, a 3D user interface. Day by day, we’re witnessing more and more diversities in computer user interface: concepts, designs, look and feel, animations, effects… While some would stick to an bare – bone, obscured text console, the others prefer some fancy, eye – candy GUI with all its bells & whistles. Things are much easier now with many 3D libraries and tools. Remind me about how I did all the 3D things: polygon, mesh, texture, sprite, shading, lighting, scene – graph, etc… with C & assembly on DOS!

vim for programmer

Published: | Categories: cs & it, linux

VIM “IDE” with symbol – browsing and auto – completion

Various utilities inside VIM: media player, calendar, file explorer…

have been using VIM for most of my daily programming, and everyday, I’ve been discovering new things about VIM. We can tune VIM into a full-fledged and powerful IDE (Integrated Development Environment) that far surpasses every others! With ctags and taglist.vim, we can build tags database, which would then enable searching, browsing all symbols, variables, functions in a code – base. cscope enhances ctags even more with advanced search & browsing features. And I would need no external diff tool since we’d already have vimdiff to compare and merge code.

Working with different types of version – control system, we’d already had vcscommand.vim, which can help interfacing with svn, cvs or git! To interact with file system, I would use NERDTree or vimExplorer, a lot of tasks with fs is done even without leaving VIM! I’m not fool enough trying to do everything with VIM, but there are many other plug-ins that you would find useful: a.vim and c.vim would help you a lot in C/C++ programming, calendar.vim helps you viewing date, and keeping small notes (diary) for each day, musicbox.vim serves you with media playing inside VIM, and vimail helps send, receiving emails with just a few convenient keystrokes!

career’s funs – 6

Published: | Categories: cs & it

he best method for accelerating a computer is the one that boosts it by 9.8 m/s2. (Anonymous)

Being good at C/C++ is like being good at using rock to chop sticks. (Anonymous)

Java is to JavaScript what Car is to Carpet. (Chris Heilmann)

Walking on water and developing software from a specification are easy if both are frozen. (Edward V Berard)

Hardware: the parts of a computer that can be kicked. (Anonymous)

The generation of random numbers is too important to be left to chance. (Anonymous)

The computer was born to solve problems that did not exist before. (Bill Gates)

In a room full of top software designers, if two agree on the same thing, that’s a majority. (Bill Curtis)

I am not out to destroy Microsoft, that would be a completely unintended side effect. (Linus Torvalds)

There are only 10 types of people in the world: Those who understand binary, and those who don’t. (Anonymous)

There are only 10 types of people in this world. Those who know ternary, those who don’t and those who confuse it with binary. (Anonymous)

fooled by randomness

Published: | Categories: cs & it, literature
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sually on my birthday, I would receive messages like: Congratulation to the Party! Congratulation to the government! Congratulation to President Ho Chi Minh! (the day happens to be also the Man’s birthday) 😬. But last month, I received this book, a nice gift from a friend, a soft – paperback hard – copy of the famous writing: Fooled by Randomness! I’m now half – way through the book, a bit difficult for non – English – native readers, but really interesting in every details!

My major hobby is teasing people who take themselves & the quality of their knowledge too seriously & those who don’t have the courage to sometimes say: I don’t know. You may not be able to change the world but… (www . fooled by randomness . com)

As with every outstanding thinkers and thinkings, the book’s caused controversies since it was first published (2001), written by Nassim Nicholas Taleb, a skeptical scholar and at the same time, a successful trader. I’ve been for long, looking forward to these types of cognitive thoughts! It’s too soon to have some comments on the book, but for now, the debate between Einstein and Heisenberg, between determinism and un – determinism would just go on!