memory-mapped files

[bearophile]

Andrei Alexandrescu:

> Indeed, time and again, "testing is believing".

Yep. Time ago I have read that the only science of "computer science" is in things like timing benchmarks and the like :-)


>      foreach (line; byLineDirect(stdin))

I don't like that byLineDirect() too much, it will become one of the most used in scripting-like programs, so it deserves to be short&easy.


>          write(r.head, ":");

Something tells me that such .head will become so common in D programs that my fingers will learn to write it while I sleep too :-)

>          r.next;

.next is clear, nice, and short. Its only fault is that it doesn't sound much like something that has side effects... I presume it's not possible to improve this situation.


>What the heck is going on? When does memory mapping actually help?<

You are scanning the file linearly, and the memory window you use is probably very small. In such situation a memory mapping is probably not the best thing. A memory mapping is useful when you for example operate with random access on a wider sliding window on the file.

Bye,
bearophile