- Write clearly -- don't be too clever.
- Say what you mean, simply and directly.
- Use library functions whenever feasible.
- Avoid too many temporary variables. [?]
- Write clearly -- don't sacrifice clarity for efficiency.
- Let the machine do the dirty work.
- Replace repetitive expressions by calls to common functions.
- Parenthesize to avoid ambiguity.
- Choose variable names that won't be confused.
- Avoid unnecessary branches.
- If a logical expression is hard to understand, try transforming it.
- Choose a data representation that makes the program simple.
- Write first in easy-to-understand pseudo language; then translate into whatever language you have to use.
- Modularize. Use procedures and functions.
- Avoid gotos completely if you can keep the program readable.
- Don't patch bad code -- rewrite it.
- Write and test a big program in small pieces.
- Use recursive procedures for recursively-defined data structures.
- Test input for plausibility and validity.
- Make sure input doesn't violate the limits of the program.
- Terminate input by end-of-file marker, not by count.
- Identify bad input; recover if possible.
- Make input easy to prepare and output self-explanatory.
- Use uniform input formats.
- Make input easy to proofread.
- Use self-identifying input. Allow defaults. Echo both on output.
- Make sure all variables are initialized before use.
- Don't stop at one bug.
- Use debugging compilers.
- Watch out for off-by-one errors.
- Take care to branch the right way on equality.
- Be careful if a loop exits to the same place from the middle and the bottom.
- Make sure your code does "nothing" gracefully.
- Test programs at their boundary values.
- Check some answers by hand.
- 10.0 times 0.1 is hardly ever 1.0.
- 7/8 is zero while 7.0/8.0 is not zero.
- Don't compare floating point numbers solely for equality.
- Make it right before you make it faster. [!]
- Make it fail-safe before you make it faster. [!]
- Make it clear before you make it faster. [!]
- Don't sacrifice clarity for small gains in efficiency. [!]
- Let your compiler do the simple optimizations.
- Don't strain to re-use code; reorganize instead.
- Make sure special cases are truly special.
- Keep it simple to make it faster. [!]
- Don't diddle code to make it faster -- find a better algorithm. [!]
- Instrument your programs. Measure before making efficiency changes.
- Make sure comments and code agree.
- Don't just echo the code with comments -- make every comment count.
- Don't comment bad code -- rewrite it.
- Use variable names that mean something.
- Use statement labels that mean something.
- Format a program to help the reader understand it.
- Document your data layouts.
Don't over-comment.
The Cathedral and the Bazaar: Musings on Linux and Open Source by an Accidental Revolutionary, by Eric S. Raymond
- Every good work of software starts by scratching a developer's personal itch.
- Good programmers know what to write. Great ones know what to rewrite (and reuse).
- Plan to throw one [version] away; you will, anyhow. (Copied from Frederick Brooks' The Mythical Man-Month)
- If you have the right attitude, interesting problems will find you.
- When you lose interest in a program, your last duty to it is to hand it off to a competent successor.
- Treating your users as co-developers is your least-hassle route to rapid code improvement and effective debugging.
- Release early. Release often. And listen to your customers.
- Given a large enough beta-tester and co-developer base, almost every problem will be characterized quickly and the fix obvious to someone.
- Smart data structures and dumb code works a lot better than the other way around.
- If you treat your beta-testers as if they're your most valuable resource, they will respond by becoming your most valuable resource.
- The next best thing to having good ideas is recognizing good ideas from your users. Sometimes the latter is better.
- Often, the most striking and innovative solutions come from realizing that your concept of the problem was wrong.
- Perfection (in design) is achieved not when there is nothing more to add, but rather when there is nothing more to take away. (Attributed to Antoine de Saint-Exupéry)
- Any tool should be useful in the expected way, but a truly great tool lends itself to uses you never expected.
- When writing gateway software of any kind, take pains to disturb the data stream as little as possible—and never throw away information unless the recipient forces you to!
- When your language is nowhere near Turing-complete, syntactic sugar can be your friend.
- A security system is only as secure as its secret. Beware of pseudo-secrets.
- To solve an interesting problem, start by finding a problem that is interesting to you.
- Provided the development coordinator has a communications medium at least as good as the Internet, and knows how to lead without coercion, many heads are inevitably better than one.