itorres

Catalonia, Spain

itorres.net

Age: 38

Most programs are too complicated — that is, more complex than they need to be to solve their problems efficiently. Why? Mostly it’s because of bad design, but I will skip that issue here because it’s a big one. But programs are often complicated at the microscopic level, and that is something I can address here.

  • 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: array, 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.

-- Rob Pike, Programming in C: Complexity

Mar
21
awarded Supporter
Mar
20
comment When I run my Python script on my Ubuntu through CRON nothing happens and I get some errors in the log file
If you don't show the actual content of your python script is hard to help you. The error shows that you're trying to run some code that expects to be run interactively on an X11 session so you will not be able to do it from cron unless you use some kind of virtual X11 server (X11VNC or similar).
Mar
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awarded Supporter
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awarded Teacher
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answered mu4e sending email fails when using proxy?
Feb
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awarded Supporter
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10
awarded Autobiographer
Dec
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comment Libcurl: force ipv4 or ipv6
On the commandline you use -4 or -6.
Dec
12
awarded Yearling
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awarded Yearling
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awarded Autobiographer
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awarded Caucus
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awarded Autobiographer
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awarded Informed
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comment Installing Grunt on OS X
@Armand, in this question npm has been installed through homebrew, hence sudo should be avoided. If a homebrew user needs to use sudo to alter /usr/local it means the install is botched.
Apr
29
comment Installing Grunt on OS X
+1 @eirikir. Reference: Homebrew FAQ: Why does Homebrew say sudo is bad?
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awarded Revival
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awarded Teacher
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answered Access DuckDuckGo without HTTPS?
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awarded Enlightened
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