The Shape of Code

I think there are two forces that will have a major impact on the shape of code in the next decade:

• Asian developers. China and India each have a population that is more than twice as large as Europe and the US combined, and software development has been kick started in these countries by a significant amount of IT out sourcing. I have one comparative data point for software developers who might be of the hacker ilk. A discussion of my C book on a Chinese blog resulted in a download volume that was 50% of the size of the one that occurred when the book appeared as a news item on Slashdot.
• Scripting languages. Software is written to solve a problem and there are only so many packaged applications (COTS or bespoke) that can profitably be supported. Scripting languages are generally designed to operate within one application domain, e.g., Bash, numerical analysis languages such as R and graphical plotting languages such as gnuplot.

While markup languages are very widely used they tend to be read and written by programs not people.

Having to read code containing non-alphabetic characters is always a shock the first time. Simply having to compare two sequences of symbols for equality is hard work. My first experience of having to do this in real time was checking train station names once I had traveled outside central Tokyo and the names were no longer also given in Romaji.

其中，ul分别是bootmap_size（bit map的size）,start_pfn(开始的页框)
                                max_low_pfn(被内核直接映射的最后一个页框的页框号) ;

Developers based in China and India have many different cultural conventions compared to the West (and each other) and I suspect that these will effect the code they write (my favorite potential effect involves treating time vertically rather than horizontally). Many coding conventions used by a given programming language community exist because of the habits adopted by early users of that language, these being passed on to subsequent users. How many Chinese and Indian developers are being taught to use these conventions, are the influential teachers spreading different conventions? I don’t have a problem with different conventions being adopted other than that having different communities using different conventions increases the cost for one community to adopt another community’s source.

Programs written in a scripting language tend to be much shorter (often being contained within a single file) and make use of much more application knowledge than programs written in general purpose languages. Their data flow tends to be relatively simple (e.g., some values are read/calculated and passed to a function that has some external effect), while the relative complexity of the control flow seems to depend on the language (I only have a few data points for both assertions).

Because of their specialized nature most scripting languages will not have enough users to support any kind of third party support tool market, e.g., testing tools. Does this mean that programs written in a scripting language will contain proportionally more faults? Perhaps their small size means that only a small number of execution paths are possible and these are quickly exercised by everyday usage (I don’t know of any research on this topic).

What code do developers write to check whether a value lies between two bounds (i.e., a between operation)?  I would write (where MIN and MAX might be symbolic names or numeric literals):

   if ( x >= MIN && x <= MAX )

that is I would check the lowest value first. Performing the test in this order just seems the natural thing to do, perhaps because I live in a culture that writes left to write and a written sequence of increasing numbers usually has the lowest number on the left.

I am currently measuring various forms of if-statement conditional expressions that occur in visible source as part of some research on if/switch usage by developers and the between operation falls within the set of expressions of interest. I was not expecting to see any usage of the form:

   if ( x <= MAX && x >= MIN )

that is with the maximum value appearing first. The first program measured threw up seven instances of this usage, all with the minimum value being negative and in five cases the maximum value being zero. Perhaps left to right ordering still applied, but to the absolute value of the bounds.

Measurements of the second and subsequent programs threw up instances that did not follow any of the patterns I had dreamt up. Of the 326 between operations appearing in the measured source 24 had what I consider to be the unnatural order. Presumably the developers using this form of between consider it to be natural, so what is their line of thinking? Are they thinking in terms of the semantics behind the numbers (in about a third of cases symbolic constants appear in the source rather than literals) and this semantics has an implied left to right order? Perhaps the authors come from a culture where the maximum value often appears on the left.

Suggestions welcome.