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  • Getters and Setters: Code smell, Necessary Evil, or Can't Live Without Them [closed]

    - by Avery Payne
    Possible Duplicate: Allen Holub wrote “You should never use get/set functions”, is he correct? Is there a good, no, a very good reason, to go through all the trouble of using getters and setters for object-oriented languages? What's wrong with just using a direct reference to a property or method? Is there some kind of "semantical coverup" that people don't want to talk about in polite company? Was I just too tired and fell asleep when someone walked out and said "Thou Shalt Write Copious Amounts of Code to Obtain Getters and Setters"? Follow-up after a year: It seems to be a common occurrence with Java, less so with Python. I'm beginning to wonder if this is more of a cultural phenomena (related to the limitations of the language) rather than "sage advice". The -1 question score is complete for-the-lulz as far as I am concerned. It's interesting that there are specific questions that are downvoted, not because they are "bad questions", but rather, because they hit someone's raw nerve.

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  • Convert object to DateRange

    - by user655832
    I'm querying an underlying PostgreSQL database using Pandas 0.8. Pandas is returning the DataFrame properly but the underlying timestamp column in my database is being returned as a generic "object" type in Pandas. As I would eventually like to seasonal normalization of my data I am curious as to how to convert this generic "object" column to something that is appropriate for analysis. Here is my current code to retrieve the data: # get records from db example import pandas.io.sql as psql import psycopg2 # define query to get all subs created this year QRY = """ select i i, i * random() f, case when random() > 0.5 then true else false end t, (current_date - (i*random())::int)::timestamp with time zone tsz from generate_series(1,1000) as s(i) order by 4 ; """ CONN_STRING = "host='localhost' port=5432 dbname='postgres' user='postgres'" # connect to db conn = psycopg2.connect(CONN_STRING) # get some data set index on relid column df = psql.frame_query(QRY, con=conn) print "Row count retrieved: %i" % (len(df),) Thanks for any help you can render. M

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  • Duplicate an AppEngine Query object to create variations of a filter without affecting the base quer

    - by Steve Mayne
    In my AppEngine project I have a need to use a certain filter as a base then apply various different extra filters to the end, retrieving the different result sets separately. e.g.: base_query = MyModel.all().filter('mainfilter', 123) Then I need to use the results of various sub queries separately: subquery1 = basequery.filter('subfilter1', 'xyz') #Do something with subquery1 results here subquery2 = basequery.filter('subfilter2', 'abc') #Do something with subquery2 results here Unfortunately 'filter()' affects the state of the basequery Query instance, rather than just returning a modified version. Is there any way to duplicate the Query object and use it as a base? Is there perhaps a standard Python way of duping an object that could be used? The extra filters are actually applied by the results of different forms dynamically within a wizard, and they use the 'running total' of the query in their branch to assess whether to ask further questions. Obviously I could pass around a rudimentary stack of filter criteria, but I'd rather use the Query itself if possible, as it adds simplicity and elegance to the solution.

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  • Business Object desgin

    - by Dan
    I have a question about how I setup my BO's. I setup the BO's to contain all of my properties of the object as well as the business logic to satisfy the business rules. I decided to make all of the methods static, but I'm not sure if that was the right decision. Someone told me to split my BO's into an Entity Object of just properties and then a BO of just methods that do business rules, and don't make the methods static. Does anyone have some experience with the way i've set this up? Any examples of how it might work better for future growth? Thanks!

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  • How to preserve object identity across different VMs

    - by wheleph
    To be specific let me illustrate the question with Spring http-remoting example. Suppose we have such implementation of a simple interface: public SearchServiceImpl implements SearchService { public SearchJdo processSearch(SearchJdo search) { search.name = "a funky name"; return search; } } SearchJdo is itself a simple POJO. Now when we call the method from a client through http-remoting we'll get: public class HTTPClient { public static void main(final String[] arguments) { final ApplicationContext context = new ClassPathXmlApplicationContext( "spring-http-client-config.xml"); final SearchService searchService = (SearchService) context.getBean("searchService"); SearchJdo search = new SearchJdo(); search.name = "myName"; // this method actually returns the same object it gets as an argument SearchJdo search2 = searchService.processSearch(search); System.out.println(search == search2); // prints "false" } } The problem is that the search objects are different because of serializaton although from logical prospective they are the same. The question is whether there are some technique that allows to support or emulate object identity across VMs.

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  • Large, high performance object or key/value store for HTTP serving on Linux

    - by Tommy
    I have a service that serves images to end users at a very high rate using plain HTTP. The images vary between 4 and 64kbytes, and there are 1.300.000.000 of them in total. The dataset is about 30TiB in size and changes (new objects, updates, deletes) make out less than 1% of the requests. The number of requests pr. second vary from 240 to 9000 and is dispersed pretty much all over, with few objects being especially "hot". As of now, these images are files on a ext3 filesystem distributed read only across a large amount of mid range servers. This poses several problems: Using a fileysystem is very inefficient since the metadata size is large, the inode/dentry cache is volatile on linux and some daemons tend to stat()/readdir() it's way through the directory structure, which in my case becomes very expensive. Updating the dataset is very time consuming and requires remounting between set A and B. The only reasonable handling is operating on the block device for backup, copying, etc. What I would like is a deamon that: speaks HTTP (get, put, delete and perhaps update) stores data it in an efficient structure. The index should remain in memory, and considering the amount of objects, the overhead must be small. The software should be able to handle massive connections with slow (if any) time needed to ramp up. Index should be read in memory at startup. Statistics would be nice, but not mandatory. I have experimented a bit with riak, redis, mongodb, kyoto and varnish with persistent storage, but I haven't had the chance to dig in really deep yet.

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  • Can running object be garbage collected?

    - by Kugel
    I have a simple class: public class Runner { public void RunAndForget(RunDelegate method) { ThreadPool.QueueUserWorkItem(new WaitCallback(Run), method); } private void Run(object o) { ((RunDelegate )o).Invoke(); } } And if I use this like so: private void RunSomethingASync() { Runner runner = new Runner(); runner.FireAndForget(new RunDelegate(Something)); } Is there any danger using it like this? My C++ guts tell me that runner object should be destroyed after RunSomethingASync is finished. Am I right? What happens then to the method running on different thread? Or perhaps it is other way around and runner will not be collected? That would be a problem considering I may call RunSomethingASync() many times.

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  • Make a usable Join relationship with LINQ on top of a database CSV design error

    - by jdk
    I'm looking for a way to fix and/or abstract away a comma-separated values (CSV) list in a database field in order to reconstruct a usable relationship such that I can properly join the two tables below and query them using LINQ and its Join method. Following is a sample showing the Person table and CsvArticleIds field having a CSV value to represent a one-to-many association with Article records. TABLE [dbo].[Person] Id Name CsvArticleIds -- ---------- -------- 1 Joe "15,22" 5 Ed "22" 10 Arnie "8,15,22" ^^^(Of course a link table should have been created; nonetheless the relationship with articles is trapped inside that list of CSV values.) TABLE [dbo].[Article] Id Title -- ---------- 8 Beginning C# 15 A Historic look at Programming in the 90s 22 Gardening in January Additional Info the fix can be at any level: C#.NET or SQL Server something easy because I will be repeating the solution for many other CSV values in other tables. Elegant is nice too. not looking for efficiency because this is part of a one-time data migration task and can take as long as it wants to run.

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  • A view model mvvm design issue

    - by Chen Kinnrot
    the best way to explain is with example so: this is the model public class Person { public int age; public string name; } this is the view model public class PersonVM { } my question is: should the vm expose the person to the datga template or encapsulate the model properties with his own properties?

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  • Some specific questions about object oriented and MVC design.

    - by Samn
    I have two objects, Users and Mail. Users create Mail objects and send them to other users. If I wanted to get all mail for a User, I could create a method like GetMail() that would return an array of Mail objects owned by that User. But if I wanted to get all mail across the system, what "type" of object would be responsible for that? To solve this problem, I usually create a Manager, which is an object responsible for dealing with a collection of a particular type of object. MailManager deals with collections of Mail objects. GetMailForUser() is one method, GetAllMail() is another method. The User objects invokes the MailManager and executes GetMailForUser(me). Is this stupid? When a user executes the controller CreateMail, a new instance of the Mail object is created. The Mail object, seeing it is creating a new Mail of type 'sent', decides to go ahead and create a second Mail object for the recipient, of type 'received'. Creating one Mail object triggers the creation of a second Mail object. Is this stupid? Should the controller have created both Mail objects, or just the first 'sent' one? When two Users are friends, the association is stored in a table of Relationships. I use a simple object for Relationships. A RelationshipManager has a method called GetFriendsForUser(). The User object has a method GetFriends(), which invokes the RelationshipManager. Is this stupid?

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  • Why would a "view" object in Interface Builder prevent my didFinishLaunchingWithOptions method from

    - by BeachRunnerJoe
    You may have already come across some of my other questions related to question, but I was having an issue with a SplitView iPad app where my application:didFinishLaunchingWithOptions method stopped executing after I went into Interface Builder and changed around the structure of my apps interface. I couldn't figure out what was preventing my didFinishLauchingWithOptions method from executing, but then I removed a "view" object I had in my view heirarchy (shown below) and suddenly my didFinishLauchingWithOptions method started executing again. I've moved passed it now, but I'm still unclear why that would cause the problem. Any ideas why that "view" object would prevent the didFinishLaunchingWithOptions method from executing?

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  • javascript filter nested object based on key value

    - by murray3
    I wish to filter a nested javascript object by the value of the "step" key: var data = { "name": "Root", "step": 1, "id": "0.0", "children": [ { "name": "first level child 1", "id": "0.1", "step":2, "children": [ { "name": "second level child 1", "id": "0.1.1", "step": 3, "children": [ { "name": "third level child 1", "id": "0.1.1.1", "step": 4, "children": []}, { "name": "third level child 2", "id": "0.1.1.2", "step": 5, "children": []} ]}, ]} ] }; var subdata = data.children.filter(function (d) { return (d.step <= 2)}); This just returns the unmodified nested object, even if I put value of filter to 1. does .filter work on nested objects or do I need to roll my own function here, advise and correct code appreciated. cjm

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  • how to return the current object?

    - by ajsie
    in code igniter you can type: $query = $this->db->query("YOUR QUERY"); foreach ($query->result() as $row) { echo $row->title; echo $row->name; echo $row->body; } i guess that the query method returns the object it's part of. am i correct? if i am, how do you type the line where it returns the object? so what i wonder is how it looks like inside the query method for the above code to be functional. public function query($sql) { // some db logic here with the $sql and saves the values to the properties (title, name and body) return X } with other words, what should X be?

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  • Hbase schema design -- to make sorting easy?

    - by chen
    I have 1M words in my dictionary. Whenever a user issue a query on my website, I will see if the query contains the words in my dictionary and increment the counter corresponding to them individually. Here is the example, say if a user type in "Obama is a president" and "Obama" and "president" are in my dictionary, then I should increment the counter by 1 for "Obama" and "president". And from time to time, I want to see the top 100 words (most queried words). If I use Hbase to store the counter, what schema should I use? -- I have not come up an efficient one yet. If I use word in my dictionary as row key, and "counter" as column key, then updating counter(increment) is very efficient. But it's very hard to sort and return the top 100. Anyone can give a good advice? Thanks.

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  • I want to design a html form in python

    - by VaIbHaV-JaIn
    when user will enter details in the text box on the html from <h1>Please enter new password</h1> <form method="POST" enctype="application/json action="uid"> Password<input name="passwd"type="password" /><br> Retype Password<input name="repasswd" type="password" /><br> <input type="Submit" /> </form> </body> i want to post the data in json format through http post request and also i want to set content-type = application/json

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  • Please recommend good books for telemetry / SCADA system design & programming

    - by Mawg
    I am looking at several projects, all with roughly the same fucntionality. Some instruments collect some data (or control some functionality). They commmunicate by Internet (Etehrnet/wifi/GPRS/sasatellite) with a databse server which stores the measurements and provides a browser based means of qeurying the data, prodcuing reports, etc (and possibly also allows control of the remote equipment). Can anyone recommend a good book describing an approach to developing such a software architecture, keeping it generic, which tools, languages. test methods, etc to use? (note to self: ask a similar question about possible existing frameworks)

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  • jQuery Ajax Methods Not Returning XHR Object

    - by Nate
    UPDATE: I haven't figured out what's going on, but this definitely seems to be a problem with my project. After creating a simple test page, I was able to verify that getJSON does in fact return an XHR object like it's supposed to. Per the stackoverflow question/answer here: Kill ajax requests using javascript using jquery. and a number of other question/answers on this site and others, the jQuery Ajax methods should return the XHR object. However, when I run the following code, request is "undefined". var request = $.getJSON(url, function(data) { console.log(data); }); console.log(request); Did I miss a change in jQuery? I'm using 1.4.4.

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  • Design considerations for a multi-language web application

    - by gAMBOOKa
    I was asked by an interviewer today how I would implement Arabic as a second language into a PHP web application. I talked about choosing a unicode encoding for the database and the front-end, and designing RTL friendly user interface modules. And he didn't seem too happy with the answer. I don't really know anything about multi-lingual systems, how would you have answered that question?

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  • GlassFish JDO and global object

    - by bach
    Hi, I'm thinking about the GlassFish platform for my new app. My app env. doesn't have a big volume of data to handle, but a lot of users writing/reading the same data A very volotile portion of the data updates every 200milsec by diff users. Therefore I'd like that type of data to be in memory only and accessible to the whole app My questions: How do I use a global object in memory with GF? a. use a static variable object - for that I guess I need to make sure GF is running on only 1 JVM -- how to I configure GF to run on 1 jvm? b. use HttpContext - same as a. How do I persist to the DB? a. can I use JDO interface? How do I Schedule tasks to be performed in the future (something like the task queue in GAE) thanks, J.S. Bach

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  • How to design a grid in Android (for multi-screen)

    - by Cris
    Hello, i need to realize an app for Android using this background image: Over every cell i have to draw a TextView, but i don't know how to do it with the different screens; i have the background image with 3 resolutions (240x320, 320x480, 480x800) but i don't know what kind of layout to use; i would use GridView but i don't know if i can work with different column size. Can anyone help me? Thanks in advance

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  • Basic class returns onject reference instead of Array

    - by php-b-grader
    I have very basic class: class Customer { protected $id; protected $customer; public function __construct($customer_id) { $this->id = $customer_id; return $this->set_customer(); } protected function set_customer() { $query = mysql_query("SELECT * FROM customer WHERE id = '$this->id'"); $this->customer = mysql_fetch_row($query); return $this->customer; } } $customer = new Customer($order->customer->id); print_r($customer); This is not doing what I want it to but I understand why... $customer returns a reference to the Customer Object... But what I want is the MySQL row array from the mysql_fetch_row() call... What am I missing?

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  • How to add values to a JSON object?

    - by Damiano
    Hello everybody, I have created an array with: var msg = new Array(); then, I have a function that add values to this array, this function is: function add(time, user, text){ var message = [time, user, text]; if (msg.length >= 50) msg.shift(); msg.push(message); } As you can see, if the array has 50 or more elements I remove the first with .shift(). Then I add an array as element. Ok, the code works perfectly, but now I have to loop the msg array to create a JSON obj. The JSON object should has this format: var obj = [ {'time' : time, 'user' : user, 'text' : text}, {'time' : time, 'user' : user, 'text' : text}, {'time' : time, 'user' : user, 'text' : text} ] I mean...i have to loop msg array and then store all the values inside the JSON object. I do not know how to "concatenate" the element of the array inside json obj. Could you help me? Thank you very much in advance!

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  • How would I design this table in SQL?

    - by RSharma
    I have a parent master table that is generic enough to hold the common information of the children. Since the children were substantially different, we created separate tables for them. So I have something like this: tblMaster -------- MasterID int Name varchar(50) --Common to all children and there are a bunch of fields like this ChildType int -- Type of Child either ChildOne or ChildTwo ChildID int -- need to store ChildOneID or ChildTwoID depending on type of Child, so that i can refer to children tblChild1 -------- ChildOneID int IDENTITY tblChild2 --------- ChildTwoID int IDENTITY Should I have a ChildID in the master that is either ChildOneID or ChildTwoID based on the ChildType column? I have a number of children and I have simplified it for this question. The other way is to add ChildOneID and ChildTwoID as columns in the master, but since i have a number of columns, I will have a lot of null columns EDIT: Any help is appreciated

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