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Danilo Shiga
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Quer estagiar em uma das empresas que mais valorizam o Bibliotecário? A Discasa está com mais uma vaga de estágio em Biblioteconomia. Se você mora em São Carlos, está cursando Biblioteconomia e sabe que Ranganathan pode ajudar uma empresa a se tornar mais eficiente, produtiva e lucrativa, aqui é o seu lugar.
Atividades supervisionadas e remuneradas que podem ser usadas para cumprir o estágio obrigatório.Venha aprender que, na era da internet, saber indexar, classificar e catalogar pode ser o diferencial competitivo em qualquer negócio.

Envie seu currículo para sti@discasa.com.br até o dia 09/01/2017
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A lesson in shortcuts.

Long ago, as the design of the Unix file system was being worked out, the entries . and .. appeared, to make navigation easier. I'm not sure but I believe .. went in during the Version 2 rewrite, when the file system became hierarchical (it had a very different structure early on).  When one typed ls, however, these files appeared, so either Ken or Dennis added a simple test to the program. It was in assembler then, but the code in question was equivalent to something like this:
   if (name[0] == '.') continue;
This statement was a little shorter than what it should have been, which is
   if (strcmp(name, ".") == 0 || strcmp(name, "..") == 0) continue;
but hey, it was easy.

Two things resulted.

First, a bad precedent was set. A lot of other lazy programmers introduced bugs by making the same simplification. Actual files beginning with periods are often skipped when they should be counted.

Second, and much worse, the idea of a "hidden" or "dot" file was created. As a consequence, more lazy programmers started dropping files into everyone's home directory. I don't have all that much stuff installed on the machine I'm using to type this, but my home directory has about a hundred dot files and I don't even know what most of them are or whether they're still needed. Every file name evaluation that goes through my home directory is slowed down by this accumulated sludge.

I'm pretty sure the concept of a hidden file was an unintended consequence. It was certainly a mistake.

How many bugs and wasted CPU cycles and instances of human frustration (not to mention bad design) have resulted from that one small shortcut about  40 years ago?

Keep that in mind next time you want to cut a corner in your code.

(For those who object that dot files serve a purpose, I don't dispute that but counter that it's the files that serve the purpose, not the convention for their names. They could just as easily be in $HOME/cfg or $HOME/lib, which is what we did in Plan 9, which had no dot files. Lessons can be learned.)

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Teremos encontro do Grupy - Ribeirão Preto amanhã, com palestras sobre testes com python, desenvolvimento de software e desenvolvimento de aplicativos iOS no Supera ás 19hrs

http://www.meetup.com/grupy-rp/events/227581789/

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É amanhã! dojo do grupy-rp, quem nunca programou em python também é bem vindo :D


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