No problem, I am sorry about that. and thanks everyone for the info, I'll take it there, very interesting stuff. Thanks.
On Jul 10, 8:07 pm, mdipierro <[email protected]> wrote: > Eric, > > I am not sure this is the place for this type of discussions. I would > recommend this mailing list instead. > > http://mail.python.org/mailman/listinfo/tutor > > Of course your questions are welcome here but there you will find more > people interested in general python programming. Here users tend to be > more focused on web development issues. In web development you tend to > avoid as much as possible loops and recursion because we are > interested in speed. > > Massimo > > On Jul 10, 6:45 pm, eric cs <[email protected]> wrote: > > > > > COOL...can you post some examples explaining what it does line by > > line? > > > what about an example of: > > Concurrent programming encompasses the programming languages and > > algorithms used to implement concurrent systems. Concurrent > > programming is usually considered to be more general than parallel > > programming because it can involve arbitrary and dynamic patterns of > > communication and interaction, whereas parallel systems generally have > > a predefined and well-structured communications pattern. The base > > goals of concurrent programming include correctness, performance and > > robustness. Concurrent systems such as operating systems are generally > > designed to operate indefinitely and not terminate unexpectedly. Some > > concurrent systems implement a form of transparent concurrency, in > > which concurrent computational entities may compete for and share a > > single resource, but the complexities of this competition and sharing > > are shielded from the programmer. > > > Because they use shared resources, concurrent systems in general > > require the inclusion of some kind of arbiter somewhere in their > > implementation (often in the underlying hardware), to control access > > to those resources. The use of arbiters introduces the possibility of > > indeterminacy in concurrent computation which has major implications > > for practice including correctness and performance. For example > > arbitration introduces unbounded nondeterminism which raises issues > > with model checking because it causes explosion in the state space and > > can even cause models to have an infinite number of states. > > > On Jul 10, 6:54 pm, rb <[email protected]> wrote: > > > > A recursive "loop" is effected by using a function (let's call it > > > "myFunc") which has two return points, one which calls itself and digs > > > deeper (eg "return myFunc(some, modified, args)") and the other which > > > unwinds the digging and returns (eg. "return (value)"). > > > > Thus if calling myFunc many times (via the first return point of the > > > func) One incurs the cost of setting up the local variables and > > > storing the return point on the return stack. When the func unwinds it > > > then must deallocate the local stack back to the system. Simple > > > iterative looping does not have this overhead. Python, being a high- > > > level interpreted language, probably has considerable overhead for > > > setting up the local stack for a func to run (compared to something > > > like C). Unwinding recursive loops into iterative loops always aids > > > performance. > > > > The (only) reason to use recursion is to express an algorithm in the > > > most elegant terms. For example, consider an algorithm which is > > > defined in recursive terms like the Fibonacci series. Using recursion > > > to determine the nth Fibonacci number is quite natural. However, > > > coding loops into recursion for no other reason than, the language > > > doesn't have iterative loops, or simply because you CAN do it, is an > > > exercise in obfuscation. > > > > Oh, another issue to watch out for when looping recursively is that a > > > return address gets pushed onto the return stack for every loop > > > iteration. If you loop one too many times and blow your stack (overrun > > > the stack) you have just borked your system. While your mileage may > > > vary, from a BSOD to a nasty worded MessageBox from the OS, still, it > > > is definitely something which "is NOT a good thing." > > > > -- > > > my 3 cents. > > > > Rb. > > > > On Jul 10, 2:19 pm, eric cs <[email protected]> wrote: > > > > > They compare Ruby 1.9 with Python, than a Python guy change the > > > > algorithm from being recursive to being iterative and runs way > > > > faster...wow. > > > > > Can you guys explain those ways of programming with simple examples > > > > with comments? > > > > I heard is very used on functional programming (Erlang,Scala). > > > > How to iterative program in Python and Web2py? > > > > >http://antoniocangiano.com/2007/11/28/holy-shmoly-ruby-19-smokes-pyth... > > > > >http://www.mysoftparade.com/blog/ruby-19-doesnt-smoke-python-away/ > > > > > Thanks. > > > > > more:http://en.wikipedia.org/wiki/Iteration-Hidequoted text - > > > > - Show quoted text -- Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "web2py Web Framework" group. 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