Re: Efficient programming

Let's look at your requirements:

bug free: this has nothing to do with efficiency. A program which is not bug free, is just wrong. Of course for any but very simple programs you cannot be sure that there are no bugs lurking inside.
less time and memory use: These may be conflicting requrements. Perl easily trades memory for speed and with memory being cheap this is an acceptable trade-off. Now, neither speed nor memory use as such are matters to be too worried about. For example a script written for a one time task: I can make it run faster by 50% by reviewing the code and spending one hour of work. Is it worth the bother if it speeds-up the script from 1 minute to 30 seconds? Even big, repetitively run programs may be scheduled during night time and nobody will care if they take "too" long, as long as their job is done when the results are due.
The same arguments go for memory consumption. Squeezing the last byte out of a memory structure may not be worth it. It all depends on what is required of it.
Easily understandable: if you mean by that "easy to maintain", I fully agree. But that is the most difficult part. Shy away from "too clever" constructs, use well tried and/or standard modules, comments and documentation are of course required and a full test suite (best written before you start to code) is a must.

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

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