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  • foo and _foo - about variables inside a class

    - by kame
    class ClassName(object): """ """ def __init__(self, foo, bar): """ """ self.foo = foo # read-write property self.bar = bar # simple attribute def _set_foo(self, value): self._foo = value def _get_foo(self): return self._foo foo = property(_get_foo, _set_foo) a = ClassName(1,2) #a._set_foo(3) print a._get_foo() When I print a._get_foo() the function _get_foo prints the variable self._foo . But where does it come from? self._foo and self.foo are different, aren't they?

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  • What's the Difference Between These Two Ruby Class Initialaztion Definitions?

    - by michaelmichael
    I'm working through a book on Ruby, and the author used a slightly different form for writing a class initialization definition than he has in previous sections of the book. It looks like this: class Ticket attr_accessor :venue, :date def initialize(venue, date) self.venue = venue self.date = date end end In previous sections of the book, it would've been defined like this: class Ticket attr_accessor :venue, :date def initialize(venue, date) @venue = venue @date = date end end Is there any functional difference between using the setter method, as in the first example vs. using the instance variable in the second? They both seem to work. Even mixing them up seems to work: class Ticket attr_accessor :venue, :date def initialize(venue, date) @venue = venue self.date = date end end

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  • Java newbie problem: classes of the same package accessing one another?

    - by HH
    Test.java and SetWord.java belong to the package tools. Test.java needs to access SetWord but an odd error 'cannot find' SetWord appear. The package limits the visibility, it works without 'package tools;' lines. How can I acess the SetWords with Test in the same pkg? In general, how can classes access one another in the same pkg? Test.java package tools; import java.io.*; import java.util.*; public class Test{ public static void main(String[] args) { //IT CANNOT FIND SetWords despite the same folder, why? SetWord sw=new SetWord(); System.out.println(st.set("HELLO)"); } } SetWord.java package tools; import java.io.*; import java.util.*; public class SetWord{ public SetWord(){} public String set(String s) { return s.trim().toLowerCase(); } }

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  • JButtons re-enable themselves after being disabled

    - by Anarchist
    I have an array of JButtons which form a keypad interface. After six numbers are entered I want to disable the keypad so that no further numbers can be entered by the user. I have written the code and the buttons do disable until the mouse hovers above any of them, then the buttons seem to re-enable themselves and run actionEvents added to them. The full code is available here. Possible things that I think are wrong. There is some sort of MouseListener which is ignoring when I set button.setEnabled(false); I haven't separated attributes from the buildGUI(); correctly, I only did this anyway so that the inner class could access them. Possibly something to do with the gridLayout as disabling the buttons seems to work for my services JPanel buttons.

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  • Codeigniter: simple form function

    - by Kevin Brown
    I'm stuck writing a simple form...I feel dumb. Here's my controller: function welcome_message(){ //Update welcome message $id = $this->session->userdata('id'); $profile['welcome_message'] = $this->input->post('welcome_message'); $this->db->update('be_user_profiles',$profile, array('user_id' => $id)); } And the html: <?php print form_open('home/welcome_message')?> <input type="checkbox" value="0" checked="false">Don't show me this again</input> <p> <input class="button submit" type="submit" class="close-box" value="Close" /> </p> <?php print form_close()?> Edit I simply need it to submit to a private function and return to the home page (page submitted from).

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  • Problems with Ruby "||" "or"?

    - by Kevin
    Beginning Ruby Question: I'm trying to see if a string variable's contents is either "personal" "email" or "password". I'm trying: if params[:action] == "password" || "email" || "personal" foo else don't foo end But that doesn't work and returns strange results, and using IRB to play around with "or" statements I have no idea why the following happens: irb(main):040:0> a = "email" => "email" irb(main):041:0> a == "password" || "email" => "email" irb(main):042:0> a == "email" || "password" => true I just want something that if any of the 3 variables are true no matter what order they are in it returns true, if not it returns false. Anyone want to help this n00b out?

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  • c++ meaning of the use of const in the signature

    - by jbu
    Please help me understand the following signature: err_type funcName(const Type& buffer) const; so for the first const, does that mean the contents of Type cannot change or that the reference cannot change? secondly, what does the second const mean? I don't really even have a hint. Thanks in advance, jbu

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  • simple putStrLn in Haskell/Yampa with arrows syntax

    - by sisif
    i'm using Haskell with the Yampa FRP library which uses the arrows language extension. how can i do a simple putStrLn in a SF? mySF = proc x -> do y <- identity -< x*x putStrLn "Hello World!" ++ show y returnA -< y the arrow syntax complains about the expression not bein an arrow (of course), but even with arrows i get no output output <- identity -< putStrLn "Hello World!"

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  • Copy and pasting code into the Python interpreter

    - by wpeters
    There is a snippet of code that I would like to copy and paste into my Python interpreter. Unfortunately due to Python's sensitivity to whitespace it is not straightforward to copy and paste it a way that makes sense. (I think the whitespace gets mangled) Is there a better way? Maybe I can load the snippet from a file. This is just an small example but if there is a lot of code I would like to avoid typing everything from the definition of the function or copy and pasting line by line. class bcolors: HEADER = '\033[95m' OKBLUE = '\033[94m' OKGREEN = '\033[92m' WARNING = '\033[93m' FAIL = '\033[91m' ENDC = '\033[0m' def disable(self): self.HEADER = '' # I think stuff gets mangled because of the extra level of indentation self.OKBLUE = '' self.OKGREEN = '' self.WARNING = '' self.FAIL = '' self.ENDC = ''

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  • What are the books about Open-Source that everyone interested in should read?

    - by Edu Zamora
    Currently I am working and running my first Open-Source project and though I am quite happy how things are working so far, I have the feeling that a lot of things could be done better. So, what books about Open-Source would you recommend me in order to help filling this gap and making things better every day? What are the books that influenced you the most? I am especially interested in: - How to organize and run an Open-Source project - Best practices - Manage and involve users and developers - How to announce and do the releases - Legal issues

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  • Definition of variables/fields type within a constructor, how is it done?

    - by elementz
    I just had a look at Suns Java tutorial, and found something that totally confused me: Given the following example: public Bicycle(int startCadence, int startSpeed, int startGear) { gear = startGear; cadence = startCadence; speed = startSpeed; } Why is it, that the types of the variables (fields?) gear, cadence and speed do not need to be defined? I would have written it as follows: public Bicycle(int startCadence, int startSpeed, int startGear) { int gear = startGear; int cadence = startCadence; int speed = startSpeed; } What would be the actual differnce?

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  • Why can't I access the instance.__class__ attribute in Python?

    - by froadie
    I'm new to Python, and I know I must be missing something pretty simple, but why doesn't this very, very simple code work? class myClass: pass testObject = myClass print testObject.__class__ I get the following error: AttributeError: class myClass has no attribute '__class__' Doesn't every object in Python have a __class__ attribute?

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  • give feedback on this pointer program

    - by JohnWong
    This is relatively simple program. But I want to get some feedback about how I can improve this program (if any), for example, unnecessary statements? #include<iostream> #include<fstream> using namespace std; double Average(double*,int); int main() { ifstream inFile("data2.txt"); const int SIZE = 4; double *array = new double(SIZE); double *temp; temp = array; for (int i = 0; i < SIZE; i++) { inFile >> *array++; } cout << "Average is: " << Average(temp, SIZE) << endl; } double Average(double *pointer, int x) { double sum = 0; for (int i = 0; i < x; i++) { sum += *pointer++; } return (sum/x); } The codes are valid and the program is working fine. But I just want to hear what you guys think, since most of you have more experience than I do (well I am only a freshman ... lol) Thanks.

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  • Sort database entries via a dropdown list

    - by Lin
    Hello! I'm curious if anyone could possibly help me, because I can't find anything exactly related to it anywhere, and it's driving me nuts. I'd like to have a dropdown list on a page, that will give the visitor the option to sort all entries by year. I have entries from i.e. 2001, 2005, 2009, 2010. The years should be displayed in the dropdown, so the visitor can easily just select all entries dated 2001 if they want. The year for each entry is located in the one database table I have. In other words, I simply want a "sort by" dropdown that you can see on pretty much any shopping site nowadays. But with set years. Thanks in advance for any replies!

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  • mapping list of different types implementing same function?

    - by sisif
    I want to apply a function to every element in a list (map) but the elements may have different types but all implement the same function (here "putOut") like an interface. However I cannot create a list of this "interface" type (here "Outputable"). How do I map a list of different types implementing the same function? main :: IO () main = do map putOut lst putStrLn "end" where lst :: [Outputable] -- ERROR: Class "Outputable" used as a type lst = [(Out1 1),(Out2 1 2)] class Outputable a where putOut :: a -> IO () -- user defined: data Out1 = Out1 Int deriving (Show) data Out2 = Out2 Int deriving (Show) instance Outputable Out1 where putOut out1 = putStrLn $ show out1 instance Outputable Out2 where putOut out2 = putStrLn $ show out2 I cannot define it this way: data Out = Out1 Int | Out2 Int Int putOut Out1 = ... putOut Out2 = ... because this is a library and users should be able to extend Out with their own types

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  • array, I/O file and standard deviation (c++)

    - by JohnWong
    double s_deviation(double data[],int cnt, double mean) { int i; double sum= 0; double sdeviation; double x; //x = mean(billy,a_size); for(i=0; i<cnt; i++) { sum += ((data[i]) - (mean)); } sdeviation = sqrt(sum/((double)cnt)); return sdeviation; } When I cout the result from this function, it gave me NaN. I tested the value of (mean) and data[i] using return data[i] and return mean they are valid. when i replaced mean with an actual number, the operation returned a finite number. but with mean as a variable, it produced NaH. I can't see anything wrong with my code at the moment. Again, I am sure mean, data are getting the right number based on those tests. Thank you

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