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  • Measuring the time to create and destroy a simple object

    - by portoalet
    From Effective Java 2nd Edition Item 7: Avoid Finalizers "Oh, and one more thing: there is a severe performance penalty for using finalizers. On my machine, the time to create and destroy a simple object is about 5.6 ns. Adding a finalizer increases the time to 2,400 ns. In other words, it is about 430 times slower to create and destroy objects with finalizers." How can one measure the time to create and destroy an object? Do you just do: long start = System.nanoTime(); SimpleObject simpleObj = new SimpleObject(); simpleObj.finalize(); long end = System.nanoTime(); long time = end - start;

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  • How to merge existing row with new data in SQLite?

    - by CSharperWithJava
    I have a database full of simple note data, with columns for title, due date, priority, and details. There is also a _id column PRIMARY KEY int. Say I have a note in the table already with some data filled and the rest null. I also have a set of data that will fill all those fields. Is there a way that I can only write data to the fields that are NULL? I can't overwrite existing data, but I'd like to add data to NULL columns. I know the rowId of the target row. If my target row had rowId of 5, I could do something like this: UPDATE SET duedate='some date', priority='2', details='some text' WHERE _id=5 But that would overwrite all the data in that row, and I don't want to lose any data that might be there. How can I change this statement to avoid writing to non-null fields?

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  • What is the ISO C++ way to directly define a conversion function to reference to array?

    - by ben
    According to the standard, a conversion function has a function-id operator conversion-type-id, which would look like, say, operator char(&)[4] I believe. But I cannot figure out where to put the function parameter list. gcc does not accept either of operator char(&())[4] or operator char(&)[4]() or anything I can think of. Now, gcc seems to accept (&operator char ())[4] but clang does not, and I am inclined to not either, since it does not seem to fit the grammar as I understand it. I do not want to use a typedef because I want to avoid polluting the namespace with it.

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  • Can git switch branch without the modification

    - by hguser
    I have a project which have completed the basic models(at master), then I commit them. Then I create two branchs user and product using: git checkout -b user git checkout -b product git checkout user Then I add the codes in the user branch, but I found that I have to make some changes for the basic models. Then I switch to master: git checkout master But I found that the modification I made in the user branch is visible in the working directory now. How to avoid this? Since the change to master and modification will be frequency.

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  • jQuery UI: moving items from one list to another

    - by AnC
    While this should be relatively straightforward, I can't figure out how to move (rather than copy) LI elements between ULs. All I want is to drag any item from list foo to list bar (or vice versa) without duplicating the element. While connectToSortable does almost exactly what I want (though I'd prefer to avoid sortable), it clones the element - and manually removing the original element by reacting to the stop event turns out to be not so easy (e.g. ensuring that a valid drop actually happened). A simple "hello world" example would help me greatly.

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  • Multiple levels of 'collection.defaultdict' in Python

    - by Morlock
    Thanks to some great folks on SO, I discovered the possibilities offered by collections.defaultdict, notably in readability and speed. I have put them to use with success. Now I would like to implement three levels of dictionaries, the two top ones being defaultdict and the lowest one being int. I don't find the appropriate way to do this. Here is my attempt: from collections import defaultdict d = defaultdict(defaultdict) a = [("key1", {"a1":22, "a2":33}), ("key2", {"a1":32, "a2":55}), ("key3", {"a1":43, "a2":44})] for i in a: d[i[0]] = i[1] Now this works, but the following, which is the desired behavior, doesn't: d["key4"]["a1"] + 1 I suspect that I should have declared somewhere that the second level defaultdict is of type int, but I didn't find where or how to do so. The reason I am using defaultdict in the first place is to avoid having to initialize the dictionary for each new key. Any more elegant suggestion? Thanks pythoneers!

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  • Is shortening properties names worth it?

    - by raam86
    in how to node Blog rolling with node.js and mongoDB the author mentions it's a good idea to shorten proprieties names: ....oft-reported issue with mongoDB is the size of the data on the disk... each and every record stores all the field-names .... This means that it can often be more space-efficient to have properties such as 't', or 'b' rather than 'title' or 'body', however for fear of confusion I would avoid this unless truly required! I am aware of solutions of how to do it I am more intrested in when is it truly required?

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  • Download and replace Android resource files

    - by Casebash
    My application will have some customisation for each company that uses it. Up until now, I have been loading images and strings from resource files. The idea is that the default resources will be distributed with the application and company specific resources will be loaded from our server after they click on a link from an email to launch the initialisation intent. Does anyone know how to replace resource files? I would really like to keep using resource files to avoid rewriting a lot of code/XML. I would distribute the application from our own server, rather than through the app store, so that we could have one version per company, but unfortunately this will give quite nasty security warnings that would concern our customers.

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  • In java can i have more than one class/object in a file?

    - by David
    So the way i've been told to do things is you have your file and the file name is Classname.java and then the code is something like this: class ClassName { SOME METHODS main {} } and then thats all. I'd like to have two objects defined and used within the same .java file. (i don't want to have to put the other class in a difernt file just because i'd like to send this to someone and i want to avoid hasstle of atatching multiple files to an email [the lazy do make good programers though if you think about it]) is it possible to do this? do i have to do anything special and if so what? what are some mistakes i'm likely to make or that you have made in the past when doing this?

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  • Unwanted behaviour from dict.fromkeys

    - by Anthony Labarre
    Hi there, I'd like to initialise a dictionary of sets (in Python 2.6) using dict.fromkeys, but the resulting structure behaves strangely. More specifically: >>>> x = {}.fromkeys(range(10), set([])) >>>> x {0: set([]), 1: set([]), 2: set([]), 3: set([]), 4: set([]), 5: set([]), 6: set([]), 7: set([]), 8: set([]), 9: set([])} >>>> x[5].add(3) >>>> x {0: set([3]), 1: set([3]), 2: set([3]), 3: set([3]), 4: set([3]), 5: set([3]), 6: set([3]), 7: set([3]), 8: set([3]), 9: set([3])} I obviously don't want to add 3 to all sets, only to the set that corresponds to x[5]. Of course, I can avoid the problem by initialising x without fromkeys, but I'd like to understand what I'm missing here.

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  • One configuration per domain name on the same application. How to easily access config values from m

    - by Aymeric
    Hi, I run a Ruby on Rails website that have multiple domain names. I have a "Website" table in the database that stores the configuration values related to each domain name: Website - domain - name - tagline - admin_email - etc... At the moment, I load the website object at the start of each request (before_filter) in my ApplicationController: @website = Website.find_by_domain(request.host) The problem is when I need to access the @website object from my models methods. I would like to avoid to have to pass @website everywhere. The best solution would be to have something similar to APP_CONFIG but per domain name. def sample_model_property - - "#{@website.name} is a great website!" end How would you do it?

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  • PHP => Alternative to session data?

    - by Armz
    i have a Web Application where Cookies and Session are both important. Since the Web Application is load balanced on different server, i am looking for suggestions to Alternative Store for the Session data that all server will be able to access. Some sessions could live up to severals days. The solutions that come to my mind: - Native PHP Sessions (this is the one i want to stop using) - MySQL Database - Serialize and write to a file (i want to avoid this, for performances) - Memcache (however it could become very big or older data getting knocked out) Thanks in advance!

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  • Does ASP.NET Make Request Scheduling Decisions Based Upon SessionID?

    - by Mike Murphy
    I know that a properly implemented SessionStateStoreProvider maintains an exclusive lock on session data for the duration of a request. However, considering that multiple requests could arrive simultaneously (e.g. via IFRAMEs) all but one would be able to make forward progress. All the other requests would block for a bit and reduce the number of worker threads available during that time. It seems if ASP.NET "peeked" at the session IDs on the requests early on, it could avoid running requests simultaneously that were on the same session. This would improve throughput under load for pages that didn't want to give up using IFRAMEs. This seems plausible enough that it might be true.

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  • How to efficiently implement a blocking call with Rails, while letting the client wait for the reply

    - by Kyle Heironimus
    We have a web service written in Rails. The API is published and we cannot change it. Our app communicates with a remote web service that sometimes hangs or takes several seconds to reply. Client -> Our Web Service -> Remote Web Service Currently, if the remote web service hangs for 5 seconds, one of our rails processes on our web service also hangs with it, which is what we need to avoid. I've seen things such as mod-x-sendfile, modporter, and delayed jobs, but the best I can tell, they all assume the client is not waiting for an answer. Since the API is already established, we cannot tell the client "I'm attempting to do what you want, check back later for the answer." The best option we have come up with so far is to add a second, non-rails web server running eventmachine to process these particular calls. Is there a better way?

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  • GUID.TryParse() ?

    - by Jack Marchetti
    Obviously there is no public GUID.TryParse() in .NET CLR 2.0. So, I was looking into regular expressions [aka googling around to find one] and each time I found one there was a heated argument in the comments section about RegEx A doesn't work, use RegEx B. Then someone would write Regex C yadda yadda So anyway, What I decided to do was this, but I feel bad about it. public static bool IsGuid (string possibleGuid) { try { Guid gid = new Guid(possibleGuid); return true; } catch (Exception ex) { return false; } } Obviously I don't really like this since it's been drilled into me since day one to avoid throwing exceptions if you can defensibly code around it. Does anyonek now why there is no public Guid.TryParse() in the .NET Framework? Does anyone have a real Regular Expression that will work for all GUIDs?

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  • Set Hibernate session's flush mode in Spring

    - by glaz666
    I am writing integration tests and in one test method I'd like to write some data to DB and then read it. @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = {"classpath:applicationContext.xml"}) @TransactionConfiguration() @Transactional public class SimpleIntegrationTest { @Resource private DummyDAO dummyDAO; /** * Tries to store {@link com.example.server.entity.DummyEntity}. */ @Test public void testPersistTestEntity() { int countBefore = dummyDAO.findAll().size(); DummyEntity dummyEntity = new DummyEntity(); dummyDAO.makePersistent(dummyEntity); //HERE SHOULD COME SESSION.FLUSH() int countAfter = dummyDAO.findAll().size(); assertEquals(countBefore + 1, countAfter); } } As you can see between storing and reading data, the session should be flushed because the default FushMode is AUTO thus no data can be actually stored in DB. Question: Can I some how set FlushMode to ALWAYS in session factory or somewhere else to avoid repeating session.flush() call? All DB calls in DAO goes with HibernateTemplate instance. Thanks in advance.

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  • Passing operator as a parameter

    - by nacho4d
    Hi, I want to have a function that evaluates 2 bool vars (like a truth table) for example: since T | F : T then myfunc('t', 'f', ||); /*defined as: bool myfunc(char lv, char rv, ????)*/ should return true; how can I pass the third parameter? (I know is possible to pass it as a char* but then I will have to have another table to compare operator string and then do the operation which is something I would like to avoid) Is it possible to pass an operator like ^(XOR) or ||(OR) or &&(AND), etc in a function/method? Thanks in advance

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  • sqrt(int_value + 0.0) ? The point?

    - by Earlz
    Hello, while doing some homework in my very strange C++ book, which I've been told before to throw away, had a very peculiar code segment. I know homework stuff always throws in extra "mystery" to try to confuse you like indenting 2 lines after a single-statement for-loop. But this one I'm confused on because it seems to serve some real-purpose. basically it is like this: int counter=10; ... if(pow(floor(sqrt(counter+0.0)),2) == counter) ... I'm interested in this part especially: sqrt(counter+0.0) Is there some purpose to the +0.0? Is this the poormans way of doing a static cast to a double? Does this avoid some compiler warning on some compiler I do not use? The entire program printed the exact same thing and compiled without warnings on g++ whenever I left out the +0.0 part. Maybe I'm not using a weird enough compiler?

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  • Persisting sensitve data in asp.net, odd implementation

    - by rawsonstreet
    For reasons not in scope of this question I have implemented a .net project in an iframe which runs from a classic asp page. The classic asp site persisted a few sensitive values by hitting the db on each page. I have passed there variables as xml to the aspx page, now I need to make these values available on any page of this .net site. I've looked into the cache object but we are on a web farm so I am not sure it would work. Is there a way I can can instantiate an object in a base page class and have other pages inherit from the base page to access these values? What is the best way to persist these values? A few more points to consider the site runs in https mode and I cannot use session variables, and I would like to avoid cookies if possible..

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  • Refresh combo box in Windows Form VB.NET

    - by fireBand
    Following is the code to populate combobox using DataSource Dim CountryList As Array = MyCtrl.GetAllCountries With cbCountyList .DataSource = CountryList .DisplayMember = "CountryName" .ValueMember = "CountryID" End With After adding a new COuntry Name to Database I want to reflect the changes in combobox. Repeating this code is not an option becasue it triggers SelectIndexChange event and had to do some crappy work around to avoid that. So I was wondering if there is way to refresh the combobox list. I actually thought binding with the DataSource property supposed to do it automatically. I also tried cbCountyList.Refresh() Thanks in advance.

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  • How to have NHibernate persist a String.Empty property value as NULL

    - by Todd
    I have a fairly simple class that I want to save to SQL Server via NHibernate (w/ Fluent mappings). The class is made up mostly of optional string fields. My problem is I default the class fields to string.empty to avoid NullRefExceptions and when NHibernate saves the row to the database each column contains an empty string instead of null. Question: Is there a way for me to get NHibernate to automatically save null when the string property is an empty string? Or do I need to litter my code with if (string.empty) checks?

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  • Javascript & jquery : Unable to increment within a form

    - by Daniyal
    I got a simple increment function like this: $(function(){ $("#inc").click(function(){ var value = parseInt($(":text[name='ice_id']").val()) + 1; $(":text[name='ice_id']").val(value); }); $("#dec").click(function(){ var value = parseInt($(":text[name='ice_id']").val()) - 1; $(":text[name='ice_id']").val(value); }); }); the ice_id text field is embedded within a form <form id="masterSubmit" name="masterSubmit" action="" method="post"> <td><input id="ice_id" type="text" name="ice_id" size="16" maxlength="15"></td> </form> When I try now to increment , it successfully increments a number, but shows the following weird behavior: It 'refreshes' the site, so that the content of the text field is gone. This behavior disappears, if I comment out the form tags ...unfortunately the form tags are required for an AJAX-submit. Are there any ways to avoid this problem? Thanks in advance for any hints and best regards Daniyal

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  • Unreachable, existing variable

    - by Oden
    I'm new at as3, maybe thats the reason why i don't understand, why the setInterval causes an error. <mx:Script> <![CDATA[ import flash.utils.setInterval; import mx.controls.Alert; [Bindable] public var MyInt:int = 500; setInterval(function():void{ ++MyInt; },1000); ]]> </mx:Script> I have a label where the value of MyInt gets visible, the bind works perfect, i've tested it several ways, and i i create a button it grows the number, but if i use the setInterval function i get an error: Access of undefined property myInt. Why? What does cause this? Please explain it, so I can avoid errors like this. Thanks

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  • Parsing HTML using HTTP Agility Pack

    - by Pajci
    Here is one table out of 5: <h3>marec - maj 2009</h3> <div class="graf_table"> <table summary="layout table"> <tr> <th>DATUM</th> <td class="datum">10.03.2009</td> <td class="datum">24.03.2009</td> <td class="datum">07.04.2009</td> <td class="datum">21.04.2009</td> <td class="datum">05.05.2009</td> <td class="datum">06.05.2009</td> </tr> <tr> <th>Maloprodajna cena [EUR/L]</th> <td>0,96000</td> <td>0,97000</td> <td>0,99600</td> <td>1,00800</td> <td>1,00800</td> <td>1,01000</td> </tr> <tr> <th>Maloprodajna cena [SIT/L]</th> <td>230,054</td> <td>232,451</td> <td>238,681</td> <td>241,557</td> <td>241,557</td> <td>242,036</td> </tr> <tr> <th>Prodajna cena brez dajatev</th> <td>0,33795</td> <td>0,34628</td> <td>0,36795</td> <td>0,37795</td> <td>0,37795</td> <td>0,37962</td> </tr> <tr> <th>Trošarina</th> <td>0,46205</td> <td>0,46205</td> <td>0,46205</td> <td>0,46205</td> <td>0,46205</td> <td>0,46205</td> </tr> <tr> <th>DDV</th> <td>0,16000</td> <td>0,16167</td> <td>0,16600</td> <td>0,16800</td> <td>0,16800</td> <td>0,16833</td> </tr> </table> </div> I have to extract out values, where table header is DATUM and Maloprodajna cena [EUR/L]. I am using Agility HTML pack. this.htmlDoc = new HtmlAgilityPack.HtmlDocument(); this.htmlDoc.OptionCheckSyntax = true; this.htmlDoc.OptionFixNestedTags = true; this.htmlDoc.OptionAutoCloseOnEnd = true; this.htmlDoc.OptionOutputAsXml = true; // is this necessary ?? this.htmlDoc.OptionDefaultStreamEncoding = System.Text.Encoding.Default; I had a lot of trouble with getting those values out. I started with: var query = from html in doc.DocumentNode.SelectNodes("//div[@class='graf_table']").Cast<HtmlNode>() from table in html.SelectNodes("//table").Cast<HtmlNode>() from row in table.SelectNodes("tr").Cast<HtmlNode>() from cell in row.SelectNodes("th|td").Cast<HtmlNode>() select new { Table = table.Id, CellText = cell.InnerHtml }; but could not figure out a way to select only values where table header is DATUM and Maloprodajna cena[EUR/L]. Is it possible to do that with where clause? Then I ended with those two queries: var date = (from d in htmlDoc.DocumentNode.SelectNodes("//div[@class='graf_table']//table//tr[1]/td") select DateTime.Parse(d.InnerText)).ToArray(); var price = (from p in htmlDoc.DocumentNode.SelectNodes("//div[@class='graf_table']//table//tr[2]/td") select double.Parse(p.InnerText)).ToArray(); Is it possible to combine those two queries? And how would I convert that to lambda expression? I just started to learn those things and I would like to know how it is done so that in the future I would not have those question. O, one more question ... does anybody know any graph control, cause I have to show those values in graph. I started with Microsoft Chart Controls, but I am having trouble with setting it. So if anyone has any experience with it I would like to know how to set it, so that x axle will show all values not every second ... example: if I have: 10.03.2009, 24.03.2009, 07.04.2009, 21.04.2009, 05.05.2009, 06.05.2009 it show only: 10.03.2009, 07.04.2009, 05.05.2009, ect. I bind data to graph like that: chart1.Series["Series1"].Points.DataBindXY(date, price); I lot of questions for my fist post ... hehe, hope that I was not indistinct or something. Thank's for any reply!

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  • Unique constraint with nullable column

    - by Álvaro G. Vicario
    I have a table that holds nested categories. I want to avoid duplicate names on same-level items (i.e., categories with same parent). I've come with this: CREATE TABLE `category` ( `category_id` int(10) unsigned NOT NULL AUTO_INCREMENT, `category_name` varchar(100) NOT NULL, `parent_id` int(10) unsigned DEFAULT NULL, PRIMARY KEY (`category_id`), UNIQUE KEY `category_name_UNIQUE` (`category_name`,`parent_id`), KEY `fk_category_category1` (`parent_id`,`category_id`), CONSTRAINT `fk_category_category1` FOREIGN KEY (`parent_id`) REFERENCES `category` (`category_id`) ON DELETE SET NULL ON UPDATE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_spanish_ci Unluckily, category_name_UNIQUE does not enforce my rule for root level categories (those where parent_id is NULL). Is there a reasonable workaround?

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