Thursday, January 22, 2009

Geeky Stuff: Some Good (and free) Advice on Developing Software

Found this today and thought it was useful, it was written "a long time ago" by internet measures but still is very good and relevant if you develop software.



(PS - Rob Pike is the guy in the foreground, Brian Kernighan is behind him)

Rob Pike on Complexity

Rule 1. You can't tell where a program is going to spend its time.
Bottlenecks occur in surprising places, so don't try to second guess and put in a speed hack until you've proven that's where the bottleneck is.

Rule 2. Measure. Don't tune for speed until you've measured, and even then don't unless one part of the code overwhelms the rest.

Rule 3. Fancy algorithms are slow when n is small, and n is usually small. Fancy algorithms have big constants. Until you know that n is frequently going to be big, don't get fancy. (Even if n does get big, use Rule 2 first.) For example, binary trees are always faster than splay trees for workaday problems.

Rule 4. Fancy algorithms are buggier than simple ones, and they're much harder to implement. Use simple algorithms as well as simple data structures.

The following data structures are a complete list for almost all practical programs:
linked list
hash table
binary tree

Of course, you must also be prepared to collect these into compound data structures. For instance, a symbol table might be implemented as a hash table containing linked lists of arrays of characters.

Rule 5. Data dominates. If you've chosen the right data structures and organized things well, the algorithms will almost always be self­-evident. Data structures, not algorithms, are central to programming. (See Brooks p. 102.)

Rule 6. There is no Rule 6.

From the essay "Notes on Programming in C, Feb 21 1989" by Rob Pike

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