internals

In sum: I need to write a List Comprehension in which i refer to list that is being created by the List Comprehension. This might not be something you need to do every day, but i don't think it's unusual either. Maybe there's no answer here--still, please don't tell me i ought to use a for loop. That might be correct, but it's not helpful. The reason is the problem domain: this line of code is part of an ETL module, so performance is relevant, and so is the need to avoid creating a temporary container--hence my wish to code this step in a L/C. If a for loop would work for me here, i would just

Just curious if anybody knows what Ruby technique is used to accomplish the following in the Rails framework. If I don't write, say, an index method on a Rails controller, Rails will still render the index view file if the URL matches that route. That makes sense, because my controller inherits from a parent class, which must have its own index method. However, if I do define an index method, and only tell it to set an instance variable, it still renders the appropriate view. For example: def index @weasels = Weasel.all # If I omit this line, Rails renders the index anyway. # If this behavior

given: -record(foo, {a, b, c}). I do something like this: Thing = #foo{a={1,2}, b={3,4}, c={5,6}}, Thing1 = Thing#foo{a={7,8}}. From a semantic view, Thing and Thing1 are unique entities. However, from a language implementation standpoint, making a full copy of Thing to generate Thing1 would be intensely wasteful. For example, if the record were a megabyte in size and I made a thousand "copies," each modifying a couple of bytes, I've just burned a gigabyte. If the internal structure kept track of a representation of the parent structure and each derivative marked up that parent in a way that

I am looking to redirect the standard .Net ConfigurationManager class to another file; entirely . The path is determined at runtime so I can't use configSource or such (this is not a duplicate question - I have looked at the others). I am essentially trying to duplicate what ASP.Net is doing behind the covers. Thus not only my classes should read from the new config file, but also any standard .Net stuff (the one I am specifically trying to get to work is the system.codeDom element). I have cracked open Reflector and started looking at how ASP.Net does it - it's pretty hairy and completely

I've been wondering how scanf()/printf() actually works in the hardware and OS levels. Where does the data flow and what exactly is the OS doing around these times? What calls does the OS make? And so on... David Claridge scanf() and printf() are functions in libc (the C standard library), and they call the read() and write() operating system syscalls respectively, talking to the file descriptors stdin and stdout respectively (fscanf and fprintf allow you to specify the file stream you want to read/write from). Calls to read() and write() (and all syscalls) result in a 'context switch' out of