Recursion

Here is an email I received in response to my essay on how to write unmaintainable code.

Recursion : Arjen Markus : arjen.markus@wldelft.nl : 2000-10-04

yesterday a colleague pointed me to your essay on writing unmaintainable code. I have not finished reading all of it yet, but it comes to mind that some useful techniques might still be missing. (Oh, and item 21 is a copy of item 15 — talking of Kama Sutra).

Let me list the ones that have pestered me since yesterday (most come from practical experience):

Using recursion instead of obvious do-loops:
(Careful: I have not checked this one — I just wrote it down!)
Stuff include file with fragments of actual code (parametrised with the odd #define macros to enable customisation), not just prototypes: this is code reuse at its very best!
In modern IDE (Integrated Drive Electronics)s (especially Developer Studio) obscuring the structure of your program as files are concerned is easy:
Get every source file from a different — entirely unrelated — directory and put every 10 or so in a separate project
Do not, I repeat, do not be too thorough about project dependencies Add a few, forget others, make them hierarchical
Change the compile options on a per-project and a per-file basis. In C/C++: define specific macros! I just love the ones that indicate what platform you are on.
Use files with the same name (init.c comes to mind)
Stress the differences between platforms. Even in Java you are not totally isolated from them.
Make use of native file names whenever you can. Put in lots of code to convert / to \ and vice versa.
Use configuration files that are tuned to the platform. Especially useful to distinguish between Windows 95, 98 and NT
In C/C++: use macros for the compiler
In all languages: use different versions of the same code in different files.
In Java: insist on using native methods to do arcane stuff.
Emphasize efficiency:
Clearly, the general way in Calc() to calculate x*x is very cumbersome!
I don’t follow you here.
Use compound logical statements in conjunction with negations:
The for-statement has great powers, which are not often recognised outside the IOCCC contest:

Save old code, by commenting it with various initials:

//AM i = i + l ;  - Redundancy removed, dd 2 oct 2000
//BN  i ++ ;
//
i = i + l ; // Repaired the bug introduced by AM.
//BN

Use graphical characters in comments to distinguish portions of the code:

for ( i = 0, sum = 0 ; i < N ; i ++ )
   {
   // ======= Chapter 3 ================================
   // = Calculate the sum of all things ======================
   sum = sum + array[i] ;
   // ===============================================
   }

This nicely obscures the useful statements.

Use extra elements in an array that have a special value:
(and somewhere, array[0] has been set to -999; the l is intended)

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