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• Segmenting a double array of labels

  - by Ami

  The Problem: I have a large double array populated with various labels. Each element (cell) in the double array contains a set of labels and some elements in the double array may be empty. I need an algorithm to cluster elements in the double array into discrete segments. A segment is defined as a set of pixels that are adjacent within the double array and one label that all those pixels in the segment have in common. (Diagonal adjacency doesn't count and I'm not clustering empty cells). |-------|-------|------| | Jane | Joe | | | Jack | Jane | | |-------|-------|------| | Jane | Jane | | | | Joe | | |-------|-------|------| | | Jack | Jane | | | Joe | | |-------|-------|------| In the above arrangement of labels distributed over nine elements, the largest cluster is the “Jane” cluster occupying the four upper left cells. What I've Considered: I've considered iterating through every label of every cell in the double array and testing to see if the cell-label combination under inspection can be associated with a preexisting segment. If the element under inspection cannot be associated with a preexisting segment it becomes the first member of a new segment. If the label/cell combination can be associated with a preexisting segment it associates. Of course, to make this method reasonable I'd have to implement an elaborate hashing system. I'd have to keep track of all the cell-label combinations that stand adjacent to preexisting segments and are in the path of the incrementing indices that are iterating through the double array. This hash method would avoid having to iterate through every pixel in every preexisting segment to find an adjacency. Why I Don't Like it: As is, the above algorithm doesn't take into consideration the case where an element in the double array can be associated with two unique segments, one in the horizontal direction and one in the vertical direction. To handle these cases properly, I would need to implement a test for this specific case and then implement a method that will both associate the element under inspection with a segment and then concatenate the two adjacent identical segments. On the whole, this method and the intricate hashing system that it would require feels very inelegant. Additionally, I really only care about finding the large segments in the double array and I'm much more concerned with the speed of this algorithm than with the accuracy of the segmentation, so I'm looking for a better way. I assume there is some stochastic method for doing this that I haven't thought of. Any suggestions?

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• How to call Ajax to run a PHP file while maintaining PHP & Javascript variables.

  - by Umar

  Hi Stackoverflowers. I'm using the Facebook php-sdk to get the users name and friends, right now the loading friends part takes about +3 seconds so I wanted to do it via Ajax, e.g. so the document can load and jQuery then calls an external PHP script which loads the friends (their names and their profile pictures). So to do this I did: $(document).ready(function() { var loadUrl = "http://localhost/fb/getFriends.php" ; $("#friends") .html("Hold on, your friends are loading!") .load(loadUrl); }); But I get a PHP error: Fatal error: Call to a member function api() on a non-object If I do this in the same PHP file (so I don't use Ajax at all to call it) it works fine. Now I think I understand the reason this is happening, but I don't know how to fix it. In my main index.php file I have a bunch of init and session code e.g. FB.init({ appId : '<?php echo $facebook->getAppId(); ?>', session : <?php echo json_encode($session); ?>, // don't refetch the session when PHP already has it status : true, // check login status cookie : true, // enable cookies to allow the server to access the session xfbml : true // parse XFBML }); So I'm just wondering what is the best way to treat my new separate PHP file getFriends.php in a way where it has access to all PHP/JavaScript session data/variables? If you haven't used the Facebook php-sdk I'll quickly explain what I mean: Lets say I have index.php and getUsername.php, from index.php I want to retrieve the getUsername.php file via Ajax using .load. Now the problem is getUsername.php needs to access PHP session data/Javascript Init functions which were created in index.php, so I'm thinking of ways to solve this (I'm new to PHP so sorry if this sounds silly) but I'm thinking maybe I could do a POST in jQuery Ajax and post the session data? Or maybe I could create a PHP class, so something like: class getUsername extends index{} /*Yes I'm a newbie*/ If you have a look at the php-sdk example.php link posted at the top maybe you'd better understand what variables exactly need to be accessed from a new file. Also on a different note, I'm using PHP to work out page rendering times and it seems that fetching the users name alone : // Session based API call. if ($session) { try { $uid = $facebook->getUser(); $me = $facebook->api('/me'); } catch (FacebookApiException $e) { error_log($e); } } Can take a good 4 seconds, is this normal? Once I get the users details is it good to cache it or something? -Speed isn't as important right now, for now I'm just trying to figure out this Ajax-separating php files thing. Woah this is a long post. Thanks very much for your time.

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• bin_at in dlmalloc

  - by chunhui

  In glibc malloc.c or dlmalloc It said "repositioning tricks"As in blew, and use this trick in bin_at. bins is a array,the space is allocated when av(struct malloc_state) is allocated.doesn't it? the sizeof(bin[i]) is less then sizeof(struct malloc_chunk*)? Who can describe this trick for me? I can't understand the bin_at macro.why they get the bins address use this method?how it works? Very thanks,and sorry for my poor English. /* To simplify use in double-linked lists, each bin header acts as a malloc_chunk. This avoids special-casing for headers. But to conserve space and improve locality, we allocate only the fd/bk pointers of bins, and then use repositioning tricks to treat these as the fields of a malloc_chunk*. */ typedef struct malloc_chunk* mbinptr; /* addressing -- note that bin_at(0) does not exist */ #define bin_at(m, i) \ (mbinptr) (((char *) &((m)->bins[((i) - 1) * 2])) \ - offsetof (struct malloc_chunk, fd)) The malloc_chunk struct like this: struct malloc_chunk { INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */ INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */ struct malloc_chunk* fd; /* double links -- used only if free. */ struct malloc_chunk* bk; /* Only used for large blocks: pointer to next larger size. */ struct malloc_chunk* fd_nextsize; /* double links -- used only if free. */ struct malloc_chunk* bk_nextsize; }; And the bin type like this: typedef struct malloc_chunk* mbinptr; struct malloc_state { /* Serialize access. */ mutex_t mutex; /* Flags (formerly in max_fast). */ int flags; #if THREAD_STATS /* Statistics for locking. Only used if THREAD_STATS is defined. */ long stat_lock_direct, stat_lock_loop, stat_lock_wait; #endif /* Fastbins */ mfastbinptr fastbinsY[NFASTBINS]; /* Base of the topmost chunk -- not otherwise kept in a bin */ mchunkptr top; /* The remainder from the most recent split of a small request */ mchunkptr last_remainder; /* Normal bins packed as described above */ mchunkptr bins[NBINS * 2 - 2]; /* Bitmap of bins */ unsigned int binmap[BINMAPSIZE]; /* Linked list */ struct malloc_state *next; #ifdef PER_THREAD /* Linked list for free arenas. */ struct malloc_state *next_free; #endif /* Memory allocated from the system in this arena. */ INTERNAL_SIZE_T system_mem; INTERNAL_SIZE_T max_system_mem; };

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• Nservicebus serization issue of derived types

  - by Tiju John

  Hi Guys, for the context setting, I am exchanging messages between my nServiceBus client and nSerivceBus server. its is the namespace xyz.Messages and and a class, Message : IMessage I have more messages that are in the other dlls, like xyz.Messages.Domain1, xyz.Messages.Domain2, xyz.Messages.Domain3. and messages that derive form that base message, Message. I have the endpoints defined as like : at client <UnicastBusConfig> <MessageEndpointMappings> <add Messages="xyz.Messages" Endpoint="xyzServerQueue" /> <add Messages="xyz.Messages.Domain1" Endpoint="xyzServerQueue" /> <add Messages="xyz.Messages.Domain2" Endpoint="xyzServerQueue" /> </MessageEndpointMappings> </UnicastBusConfig> at Server <UnicastBusConfig> <MessageEndpointMappings> <add Messages="xyz.Messages" Endpoint="xyzClientQueue" /> <add Messages="xyz.Messages.Domain1" Endpoint="xyzClientQueue" /> <add Messages="xyz.Messages.Domain2" Endpoint="xyzClientQueue" /> </MessageEndpointMappings> </UnicastBusConfig> and the bus initialized as IBus serviceBus = Configure.With() .SpringBuilder() .XmlSerializer() .MsmqTransport() .UnicastBus() .LoadMessageHandlers() .CreateBus() .Start(); now when i try sending instance of Message type or any type derived types of Message, it successfully sends the message over and at the server, i get the proper type. eg. Message message= new Message(); Bus.Send(message); // works fine, transfers Message type message = new MessageDerived1(); Bus.Send(message); // works fine, transfers MessageDerived1 type message = new MessageDerived2(); Bus.Send(message); // works fine, transfers MessageDerived2 type My problem arises when any type, say MessageDerived1, contains a member variable of type Message, and when i assign it to a derived type, the type is not properly transferred over the wire. It transfers only as Message type, not the derived type. public class MessageDerived2 : Message { public Message message; } MessageDerived2 messageDerived2= new MessageDerived2(); messageDerived2.message = new MessageDerived1(); message = messageDerived2; Bus.Send(message); // incorrect behaviour, transfers MessageDerived2 correctly, but looses type of MessageDerived2.Message (it deserializes as Message type, instead of MessageDerived1) any help is strongly appreciated. Thanks TJ

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• Cannot instantiate abstract class or interface : problem while persisting

  - by sammy

  i have a class campaign that maintains a list of AdGroupInterfaces. im going to persist its implementation @Entity @Table(name = "campaigns") public class Campaign implements Serializable,Comparable<Object>,CampaignInterface { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @OneToMany ( cascade = {CascadeType.ALL}, fetch = FetchType.EAGER, targetEntity=AdGroupInterface.class ) @org.hibernate.annotations.Cascade( value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN ) @org.hibernate.annotations.IndexColumn(name = "CHOICE_POSITION") private List<AdGroupInterface> AdGroup; public Campaign() { super(); } public List<AdGroupInterface> getAdGroup() { return AdGroup; } public void setAdGroup(List<AdGroupInterface> adGroup) { AdGroup = adGroup; } public void set1AdGroup(AdGroupInterface adGroup) { if(AdGroup==null) AdGroup=new LinkedList<AdGroupInterface>(); AdGroup.add(adGroup); } } AdGroupInterface's implementation is AdGroups. when i add an adgroup to the list in campaign, campaign c; c.getAdGroupList().add(new AdGroups()), etc and save campaign it says"Cannot instantiate abstract class or interface :" AdGroupInterface its not recognizing the implementation just before persisting... Whereas Persisting adGroups separately works. when it is a member of another entity, it doesnt get persisted. import java.io.Serializable; import java.util.List; import javax.persistence.*; @Entity @DiscriminatorValue("1") @Table(name = "AdGroups") public class AdGroups implements Serializable,Comparable,AdGroupInterface{ /** * */ private static final long serialVersionUID = 1L; private Long Id; private String Name; private CampaignInterface Campaign; private MonetaryValue DefaultBid; public AdGroups(){ super(); } public AdGroups( String name, CampaignInterface campaign) { super(); this.Campaign=new Campaign(); Name = name; this.Campaign = campaign; DefaultBid = defaultBid; AdList=adList; } @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name="AdGroup_Id") public Long getId() { return Id; } public void setId(Long id) { Id = id; } @Column(name="AdGroup_Name") public String getName() { return Name; } public void setName(String name) { Name = name; } @ManyToOne @JoinColumn (name="Cam_ID", nullable = true,insertable = false) public CampaignInterface getCampaign() { return Campaign; } public void setCampaign(CampaignInterface campaign) { this.Campaign = campaign; } } what am i missing?? please look into it ...

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• jQuery: How to find and change multiply th classes between n & n

  - by Ravex

  Hi everyone. I have some table structure: <tr class="row-2"><tr> <tr class="row-3">..<tr> <tr class="row-4">..<tr> <tr class="row-5">..<tr> <tr class="row-6">..<tr> <tr class="row-7"><tr> <tr class="row-8">..<tr> <tr class="row-9">..<tr> <tr class="row-10">..<tr> <tr class="row-11">..<tr> ...etc for this example TR with classes "row-2" and "row-7" is parrent product link wich expand child rows. <script> $(function() { $('tr.parent') .css("cursor","pointer") .css("color","red") .attr("title","Click to expand/collapse") .click(function(){ $(this).siblings('.child-'+this.id).toggle(); }); $('tr[@class^=child-]').hide().children('td'); }); </script> Rows -3...-6 is child of row-2 and Rows -8...-11 is child of row-7 How i can find row-2, row-7, etc then add second class "parrent" and ID similar class (id="row-2", id="row-7", etc)? Also i need add in each TR between row-2 and row-7 class equal previous parrent row. In bottom line i need something like this: <tr class="row-2 parrent" id="row-2"><tr> <tr class="row-3 child-row2">..<tr> <tr class="row-4 child-row2">..<tr> <tr class="row-5 child-row2">..<tr> <tr class="row-6 child-row2">..<tr> <tr class="row-7 parrent" id="row-7"><tr> <tr class="row-8 child-row7">..<tr> <tr class="row-9 child-row7">..<tr> <tr class="row-10 child-row7">..<tr> <tr class="row-11 child-row7">..<tr> ..etc Thanks for any Help.

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• Proper way to use Linq with WPF

  - by Ingó Vals

  I'm looking for a good guide into the right method of using Linq to Sql together with WPF. Most guides only go into the bare basics like how to show data from a database but noone I found goes into how to save back to the database. Can you answer or point out to me a guide that can answer these questions. I have a separate Data project because the same data will also be used in a web page so I have the repository method. That means I have a seperate class that uses the DataContext and there are methods like GetAllCompanies() and GetCompanyById ( int id ). 1) Where there are collections is it best to return as a IQueryable or should I return a list? Inside the WPF project I have seen reccomendations to wrap the collection in a ObservabgleCollection. 2) Why should I use ObservableCollection and should I use it even with Linq / IQueryable Some properties of the linq entities should be editable in the app so I set them to two-way mode. That would change the object in the observableCollection. 3) Is the object in the ObservableCollection still a instance of the original linq entity and so is the change reflected in the database ( when submitchanges is called ) I should have somekind of save method in the repository. But when should I call it? What happens if someone edits a field but decides not to save it, goes to another object and edits it and then press save. Doesn't the original change also save? When does it not remember the changes to a linq entity object anymore. Should I instance the Datacontext class in each method so it loses scope when done. 4) When and how to call the SubmitChanges method 5) Should I have the DataContext as a member variable of the repository class or a method variable To add a new row I should create a new object in a event ( "new" button push ) and then add it to the database using a repo method. 6) When I add the object to the database there will be no new object in the ObservableCollection. Do I refresh somehow. 7) I wan't to reuse the edit window when creating new but not sure how to dynamically changing from referencing selected item from a listview to this new object. Any examples you can point out.

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• Classifying captured data in unknown format?

  - by monch1962

  I've got a large set of captured data (potentially hundreds of thousands of records), and I need to be able to break it down so I can both classify it and also produce "typical" data myself. Let me explain further... If I have the following strings of data: 132T339G1P112S 164T897F5A498S 144T989B9B223T 155T928X9Z554T ... you might start to infer the following: possibly all strings are 14 characters long the 4th, 8th, 10th and 14th characters may always be alphas, while the rest are numeric the first character may always be a '1' the 4th character may always be the letter 'T' the 14th character may be limited to only being 'S' or 'T' and so on... As you get more and more samples of real data, some of these "rules" might disappear; if you see a 15 character long string, then you have evidence that the 1st "rule" is incorrect. However, given a sufficiently large sample of strings that are exactly 14 characters long, you can start to assume that "all strings are 14 characters long" and assign a numeric figure to your degree of confidence (with an appropriate set of assumptions around the fact that you're seeing a suitably random set of all possible captured data). As you can probably tell, a human can do a lot of this classification by eye, but I'm not aware of libraries or algorithms that would allow a computer to do it. Given a set of captured data (significantly more complex than the above...), are there libraries that I can apply in my code to do this sort of classification for me, that will identify "rules" with a given degree of confidence? As a next step, I need to be able to take those rules, and use them to create my own data that conforms to these rules. I assume this is a significantly easier step than the classification, but I've never had to perform a task like this before so I'm really not sure how complex it is. At a guess, Python or Java (or possibly Perl or R) are possibly the "common" languages most likely to have these sorts of libraries, and maybe some of the bioinformatic libraries do this sort of thing. I really don't care which language I have to use; I need to solve the problem in whatever way I can. Any sort of pointer to information would be very useful. As you can probably tell, I'm struggling to describe this problem clearly, and there may be a set of appropriate keywords I can plug into Google that will point me towards the solution. Thanks in advance

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• SWIG & Java Use of carrays.i and array_functions for C Array of Strings

  - by c12

  I have the below configuration where I'm trying to create a test C function that returns a pointer to an Array of Strings and then wrap that using SWIG's carrays.i and array_functions so that I can access the Array elements in Java. Uncertainties: %array_functions(char, SWIGArrayUtility); - not sure if char is correct inline char *getCharArray() - not sure if C function signature is correct String result = getCharArray(); - String return seems odd, but that's what is generated by SWIG SWIG.i: %module Test %{ #include "test.h" %} %include <carrays.i> %array_functions(char, SWIGArrayUtility); %include "test.h" %pragma(java) modulecode=%{ public static char[] getCharArrayImpl() { final int num = numFoo(); char ret[] = new char[num]; String result = getCharArray(); for (int i = 0; i < num; ++i) { ret[i] = SWIGArrayUtility_getitem(result, i); } return ret; } %} Inline Header C Function: #ifndef TEST_H #define TEST_H inline static unsigned short numFoo() { return 3; } inline char *getCharArray(){ static char* foo[3]; foo[0]="ABC"; foo[1]="5CDE"; foo[2]="EEE6"; return foo; } #endif Java Main Tester: public class TestMain { public static void main(String[] args) { System.loadLibrary("TestJni"); char[] test = Test.getCharArrayImpl(); System.out.println("length=" + test.length); for(int i=0; i < test.length; i++){ System.out.println(test[i]); } } } Java Main Tester Output: length=3 ? ? , SWIG Generated Java APIs: public class Test { public static String new_SWIGArrayUtility(int nelements) { return TestJNI.new_SWIGArrayUtility(nelements); } public static void delete_SWIGArrayUtility(String ary) { TestJNI.delete_SWIGArrayUtility(ary); } public static char SWIGArrayUtility_getitem(String ary, int index) { return TestJNI.SWIGArrayUtility_getitem(ary, index); } public static void SWIGArrayUtility_setitem(String ary, int index, char value) { TestJNI.SWIGArrayUtility_setitem(ary, index, value); } public static int numFoo() { return TestJNI.numFoo(); } public static String getCharArray() { return TestJNI.getCharArray(); } public static char[] getCharArrayImpl() { final int num = numFoo(); char ret[] = new char[num]; String result = getCharArray(); System.out.println("result=" + result); for (int i = 0; i < num; ++i) { ret[i] = SWIGArrayUtility_getitem(result, i); System.out.println("ret[" + i + "]=" + ret[i]); } return ret; } }

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• Delaying emails in PHP to avoid exceeding server limit

  - by Andrew P.

  Okay, so here's my problem: I have a list of members on a website, and periodically one of the admins my site (who are not very web or tech savvy) will send a newsletter to the memberlist. My current memberlist is well over 800 individuals long. So, I wrote an email script that sends the email to the full memberlist, with the members listed in the Bcc header. However, I've discovered that my host server has a limit of 300 emails per hour, which I apparently exceed even though the members are listed in the Bcc field. (I wasn't previously aware that the behaviour of Bcc was to send separate emails for each name on the list...) After some thought, I've come to the conclusion that my only solution is to have my script send only the email to only the first 300 emails, wait an hour, and send a second email to the next three hundred, wait another hour, and so on until I've sent the email to the whole member list. Looking around on the internet, I've seen some other solutions people have come up with for delaying emails in PHP. Sleep() is obviously not an option, because I can't just leave the script open and running for 3 or four hours. I've seen some people suggest cron jobs, but I'm not sure how feasible it would be to create three new cron jobs every time I send an email, use them once, and then delete them afterward. The final (and what I think is the smartest) solution I've seen, is to have a table in my database to temporarily store the emails to be delayed and sent later, and then create a cron job that checks this sql table every hour or so, compares the timestamp of the row to the current timestamp, and then sends the email if an hour has passed. So I'm asking you all which method you would recommend. Is there an easier solution that I've completely looked over (aside from getting a different hosting plan. ha!), or is there a cleaner way to do it than the database / cron job approach? tl;dr: I have 800 emails to send in an hour on a server that limits me to 300/hr. Using PHP, find a way to get around this problem in a way that the person sending the email needs only to click "send."

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• [NEWVERSION]algorithm || method to write prog[UNSOLVED] [closed]

  - by fatai

  I am one of the computer science student. Everyone solve problem with a different or same method, ( but actually I dont know whether they use method or I dont know whether there are such common method to approach problem.) if there are common method, What is it ? If there are different method, which method are you using ? All teacher give us problem which in simple form sometimes, but they donot introduce any approach or method(s) so that we cannot make a decision to choose the method then apply that one to problem , afterward find solution then write code.No help from teacher , push us to find method to solve homework. Ex: my friend is using no method , he says "I start to construct algorithm while I try to write prog." I have found one method when I failed the course, More accurately, my method: When I counter problem in language , I will get more paper and then ; first, input/ output step ; my prog will take this / these there argument(s) and return namely X , ex : in c, input length is not known and at same type , so I must use pointer desired output is in form of package , so use structure second, execution part ; in that step , I am writing all step which are goes to final output ex : in python ; 1.) [ + , [- , 4 , [ * , 1 , 2 ]], 5] 2.) [ + , [- , 4 , 2 ],5 ] 3.) [ + , 2 , 5] 4.) 7 ==> return 7 third, I will write test code ex : in c++ input : append 3 4 5 6 vector_x remove 0 1 desired output vector_x holds : 5 6 now, my other question is ; What is/are other method(s) which have/has been; used to construct class :::: for c++ , python, java used to communicate classes / computers used for solving embedded system problem ::::: for c by other user? Some programmer uses generalized method without considering prog-language(java , perl .. ), what is this method ? Why I wonder , because I learn if you dont costruct algorithm on paper, you may achieve your goal. Like no money no lunch , I can say no algorithm no prog therefore , feel free when you write your own method , a way which is introduced by someone else but you are using and you find it is so efficient

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• How to align this div contents properly?

  - by Pandiya Chendur

  Here is my layout, I am using one div and many spans for getting the above view... Look at all the rows ther are not properly aligned... <div class="resultsdiv"><br /> <span style="width:200px;" class="resultName">' + employee.Emp_Name + '</span> <span class="resultfields" style="padding-left:100px;">Category&nbsp;:</span>&nbsp; <span class="resultfieldvalues">' + employee.Desig_Name + '</span><br /><br /> <span id="SalaryBasis" class="resultfields">Salary Basis&nbsp;:</span>&nbsp;<span class="resultfieldvalues">' + employee.SalaryBasis + '</span> <span class="resultfields" style="padding-left:25px;">Salary&nbsp;:</span>&nbsp;<span class="resultfieldvalues">' + employee.FixedSalary + '</span> <span style="font-size:110%;font-weight:bolder;padding-left:25px;">Address&nbsp;:</span>&nbsp; <span class="resultfieldvalues">' + employee.Address + '</span> </div> and my css are .resultsdiv { background-color: #FFF;border-top:solid 1px #ddd; height:50px; border-bottom:solid 1px #ddd; padding-bottom:15px; width:450px; } .resultseven { background-color: #EFF1f1; } .resultshover { background-color: #F4F2F2; cursor:pointer; } .resultName { font-size:125%;font-weight:bolder;color:#476275;font-family:Arial,Liberation Sans,DejaVu Sans,sans-serif; } .resultfields { font-size:110%;font-weight:bolder;font-family:Arial,Liberation Sans,DejaVu Sans,sans-serif; } .resultfieldvalues { color:#476275;font-size:110%;font-weight:bold;font-family:Arial,Liberation Sans,DejaVu Sans,sans-serif; } Any suggestion to get it aligned properly.... Should i use divs insted of spans to get this properly aligned...

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• NullPointerException using datanucleus-json with S3

  - by Matt

  I'm using datanucleus 3.2.7 from Maven, trying to use the Amazon S3 JPA provider. I can successfully write data into S3, but querying either by using "SELECT u FROM User u" or "SELECT u FROM User u WHERE id = :id" causes a NullPointerException to be thrown. Using the RDBMS provider, everything works perfectly. Is there something I'm doing wrong? Main.java EntityManagerFactory factory = Persistence.createEntityManagerFactory("MyUnit"); EntityManager entityManager = factory.createEntityManager(); Query query = entityManager.createQuery("SELECT u FROM User u", User.class); List<User> users = query.getResultList(); // Null pointer exception here for(User u:users) System.out.println(u); User.java package test; import javax.persistence.*; @Entity @Table(name = "User") public class User { @Id public String id; public String name; public User(String id, String name) { this.id = id; this.name = name; } public String toString() { return id+" : "+name; } } persistence.xml <?xml version="1.0" encoding="UTF-8" ?> <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0"> <persistence-unit name="MyUnit"> <class>test.User</class> <exclude-unlisted-classes /> <properties> <properties> <property name="datanucleus.ConnectionURL" value="amazons3:http://s3.amazonaws.com/" /> <property name="datanucleus.ConnectionUserName" value="xxxxx" /> <property name="datanucleus.ConnectionPassword" value="xxxxx" /> <property name="datanucleus.cloud.storage.bucket" value="my-bucket" /> </properties> <property name="datanucleus.autoCreateSchema" value="true" /> </properties> </persistence-unit> </persistence> Exception java.lang.NullPointerException at org.datanucleus.NucleusContext.isClassWithIdentityCacheable(NucleusContext.java:1840) at org.datanucleus.ExecutionContextImpl.getObjectFromLevel2Cache(ExecutionContextImpl.java:5287) at org.datanucleus.ExecutionContextImpl.getObjectFromCache(ExecutionContextImpl.java:5191) at org.datanucleus.ExecutionContextImpl.findObject(ExecutionContextImpl.java:3137) at org.datanucleus.store.json.CloudStoragePersistenceHandler.getObjectsOfCandidateType(CloudStoragePersistenceHandler.java:367) at org.datanucleus.store.json.query.JPQLQuery.performExecute(JPQLQuery.java:94) at org.datanucleus.store.query.Query.executeQuery(Query.java:1786) at org.datanucleus.store.query.Query.executeWithMap(Query.java:1690) at org.datanucleus.api.jpa.JPAQuery.getResultList(JPAQuery.java:194) at test.Main.main(Main.java:16)

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• siblings in jquery hide everything

  - by user2658615

  This is my html code : <div id="tabbase"> <ul> <li>a</li> <li>b</li> </ul> <div id="tabs-0"></div> <div id="tabs-1"> <div class="width50"> <h5>title1</h5> <div class="da-desc">a</div> <button>continue</button> </div> <div class="width50"> <h5>title2</h5> <div class="da-desc">b</div> <button>continue</button> </div> </div> </div> and this is CSS code : #tabbase { margin:16px; } #tabbase ul li { display:inline-block; margin:5px 0px 5px 0; background:rgb(224,224,224); padding:5px; border:1px solid rgb(153,153,153); cursor:pointer; } #tabs-0, #tabs-1 { border:1px solid rgb(153,153,153); background:rgb(255,255,255); padding:5px; margin:-5px 0 0 0; } #tabbase ul li.active { background:rgb(255,255,255) !important; } and this is jquery code : $(document).ready(function(e) { $("#tabs-1").hide(0); $("#tabbase ul li:first").addClass("active"); $("#tabbase ul li").click(function(e) { $(this).addClass("active"); $(this).siblings(this).removeClass("active"); count = $("#tabbase ul li").index(this); $('#tabs-'+count).slideDown(500).siblings(this).slideUp(500); }); }); so you can see that when you click on a tab , all tabs are gone and how can I fix this?

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• Understanding VS2010 C# parallel profiling results

  - by Haggai

  I have a program with many independent computations so I decided to parallelize it. I use Parallel.For/Each. The results were okay for a dual-core machine - CPU utilization of about 80%-90% most of the time. However, with a dual Xeon machine (i.e. 8 cores) I get only about 30%-40% CPU utilization, although the program spends quite a lot of time (sometimes more than 10 seconds) on the parallel sections, and I see it employs about 20-30 more threads in those sections compared to serial sections. Each thread takes more than 1 second to complete, so I see no reason for them to work in parallel - unless there is a synchronization problem. I used the built-in profiler of VS2010, and the results are strange. Even though I use locks only in one place, the profiler reports that about 85% of the program's time is spent on synchronization (also 5-7% sleep, 5-7% execution, under 1% IO). The locked code is only a cache (a dictionary) get/add: bool esn_found; lock (lock_load_esn) esn_found = cache.TryGetValue(st, out esn); if(!esn_found) { esn = pData.esa_inv_idx.esa[term_idx]; esn.populate(pData.esa_inv_idx.datafile); lock (lock_load_esn) { if (!cache.ContainsKey(st)) cache.Add(st, esn); } } lock_load_esn is a static member of the class of type Object. esn.populate reads from a file using a separate StreamReader for each thread. However, when I press the Synchronization button to see what causes the most delay, I see that the profiler reports lines which are function entrance lines, and doesn't report the locked sections themselves. It doesn't even report the function that contains the above code (reminder - the only lock in the program) as part of the blocking profile with noise level 2%. With noise level at 0% it reports all the functions of the program, which I don't understand why they count as blocking synchronizations. So my question is - what is going on here? How can it be that 85% of the time is spent on synchronization? How do I find out what really is the problem with the parallel sections of my program? Thanks.

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• Unique_ptr compiler errors

  - by Godric Seer

  I am designing and entity-component system for a project, and C++ memory management is giving me a few issues. I just want to make sure my design is legitimate. So to start I have an Entity class which stores a vector of Components: class Entity { private: std::vector<std::unique_ptr<Component> > components; public: Entity() { }; void AddComponent(Component* component) { this -> components.push_back(std::unique_ptr<Component>(component)); } ~Entity(); }; Which if I am not mistaken means that when the destructor is called (even the default, compiler created one), the destructor for the Entity, will call ~components, which will call ~std::unique_ptr for each element in the vector, and lead to the destruction of each Component, which is what I want. The component class has virtual methods, but the important part is its constructor: Component::Component(Entity parent) { parent.addComponent(this) // I am not sure if this would work like I expect // Other things here } As long as passing this to the method works, this also does what I want. My confusion is in the factory. What I want to do is something along the lines of: std::shared_ptr<Entity> createEntity() { std::shared_ptr<Entity> entityPtr(new Entity()); new Component(*parent); // Initialize more, and other types of Components return entityPtr; } Now, I believe that this setup will leave the ownership of the Component in the hands of its Parent Entity, which is what I want. First a small question, do I need to pass the entity into the Component constructor by reference or pointer or something? If I understand C++, it would pass by value, which means it gets copied, and the copied entity would die at the end of the constructor. The second, and main question is that code based on this sample will not compile. The complete error is too large to print here, however I think I know somewhat of what is going on. The compiler's error says I can't delete an incomplete type. My Component class has a purely virtual destructor with an implementation: inline Component::~Component() { }; at the end of the header. However since the whole point is that Component is actually an interface. I know from here that a complete type is required for unique_ptr destruction. The question is, how do I work around this? For reference I am using gcc 4.4.6.

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• How do I debug a difficult-to-reproduce crash with no useful call stack?

  - by David M

  I am encountering an odd crash in our software and I'm having a lot of trouble debugging it, and so I am seeking SO's advice on how to tackle it. The crash is an access violation reading a NULL pointer: First chance exception at $00CF0041. Exception class $C0000005 with message 'access violation at 0x00cf0041: read of address 0x00000000'. It only happens 'sometimes' - I haven't managed to figure out any rhyme or reason, yet, for when - and only in the main thread. When it occurs, the call stack contains one incorrect entry: For the main thread, which this is, it should show a large stack full of other items. At this point, all other threads are inactive (mostly sitting in WaitForSingleObject or a similar function.) I have only seen this crash occur in the main thread. It always has the same call stack of one entry, in the same method at the same address. This method may or may not be related - we do use the VCL in our application. My bet, though, is that something (possibly quite a while ago) is corrupting the stack, and the address where it's crashing is effectively random. Note it has been the same address across several builds, though - it's probably not truly random. Here is what I've tried: Trying to reproduce it reliably at a certain point. I have found nothing that reproduces it every time, and a couple of things that occasionally do, or do not, for no apparent reason. These are not 'narrow' enough actions to narrow it down to a particular section of code. It may be timing related, but at the point the IDE breaks in, other threads are usually doing nothing. I can't rule out a threading problem, but think it's unlikely. Building with extra debugging statements (extra debug info, extra asserts, etc.) After doing so, the crash never occurs. Building with Codeguard enabled. After doing so, the crash never occurs and Codeguard shows no errors. My questions: 1. How do I find what code caused the crash? How do I do the equivalent of walking back up the stack? 2. What general advice do you have for how to trace the cause of this crash? I am using Embarcadero RAD Studio 2010 (the project mostly contains C++ Builder code and small amounts of Delphi.)

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• Difficulty adding widgets to django form.

  - by codingJoe

  I have a django app that tracks activities that can benefit a classroom. Using the django examples, I was able to build a form to enter this data. But when I try to add widgets to that form, things get tricky. What I want is a calendar widget that lets the user enter the 'activity_date' field using a widget. If I use Admin interface. The AdminDateWidget works fine. however. This particular user isn't allowed access to the admin interface so I need a different way to present this widget. Also I couldn't figure out how to make the bring the admin widget over into non-admin pages. So I tried a custom widget. This is the first custom widget I've built, so I'm not quite sure what is supposed to be going on here. Any Expert Advice? How do I get my date widget to work? # The Model class Activity(models.Model): activity_date = models.DateField() activity_type = models.CharField(max_length=50, choices=ACTIVITY_TYPES) activity_description = models.CharField(max_length=200) activity_duration= models.DecimalField(decimal_places=2, max_digits=4) est_attendance = models.IntegerField("Estimated attendance") # The Form class ActivityForm(forms.ModelForm): # The following line causes lockup if enabled. # With the DateTimeWidget removed, the form functions correctly except that there is no widget. #activity_date = forms.DateField(label=_('Date'), widget=DateTimeWidget) ##!!! Point of Error !!! class Meta: model = Activity fields = ('activity_date', 'activity_type', 'activity_description', 'activity_duration', 'est_attendance') def __init__(self, *args, **kwargs): super(ActivityForm, self).__init__(*args, **kwargs) instance = getattr(self, 'instance', None) edit_aid = kwargs.get('edit_aid', False) # On a different approach, the following also didn't work. #self.fields['activity_date'].widget = widgets.AdminDateWidget() # The Widget # Example referenced: http://djangosnippets.org/snippets/391/ calbtn = u""" <button id="calendar-trigger">...</button> <img src="%s/site_media/images/icon_calendar.gif" alt="calendar" id="%s_btn" style="cursor: pointer; border: 1px solid #8888aa;" title="Select date and time" onmouseover="this.style.background='#444444';" onmouseout="this.style.background=''" /> <script type="text/javascript"> Calendar.setup({ trigger : "calendar-trigger", inputField : "%s" }); </script>""" class DateTimeWidget(forms.widgets.TextInput): dformat = '%Y-%m-%d %H:%M' def render(self, name, value, attrs=None): print "DTWgt render name=%s, value=%s" % name, value if value is None: value = '' final_attrs = self.build_attrs(attrs, type=self.input_type, name=name) if value != '': try: final_attrs['value'] = \ force_unicode(value.strftime(self.dformat)) except: final_attrs['value'] = \ force_unicode(value) if not final_attrs.has_key('id'): final_attrs['id'] = u'%s_id' % (name) id = final_attrs['id'] jsdformat = self.dformat #.replace('%', '%%') cal = calbtn % (settings.MEDIA_URL, id, id, jsdformat, id) a = u'<input%s />%s' % (forms.util.flatatt(final_attrs), cal) print "render return %s " % a return mark_safe(a) def value_from_datadict(self, data, files, name): print "DTWgt value_from_datadict" dtf = forms.fields.DEFAULT_DATETIME_INPUT_FORMATS empty_values = forms.fields.EMPTY_VALUES value = data.get(name, None) if value in empty_values: return None if isinstance(value, datetime.datetime): return value if isinstance(value, datetime.date): return datetime.datetime(value.year, value.month, value.day) for format in dtf: try: return datetime.datetime(*time.strptime(value, format)[:6]) except ValueError: continue return None

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• How do I destruct data associated with an object after the object no longer exists?

  - by Phineas

  I'm creating a class (say, C) that associates data (say, D) with an object (say, O). When O is destructed, O will notify C that it soon will no longer exist :( ... Later, when C feels it is the right time, C will let go of what belonged to O, namely D. If D can be any type of object, what's the best way for C to be able to execute "delete D;"? And what if D is an array of objects? My solution is to have D derive from a base class that C has knowledge of. When the time comes, C calls delete on a pointer to the base class. I've also considered storing void pointers and calling delete, but I found out that's undefined behavior and doesn't call D's destructor. I considered that templates could be a novel solution, but I couldn't work that idea out. Here's what I have so far for C, minus some details: // This class is C in the above description. There may be many instances of C. class Context { public: // D will inherit from this class class Data { public: virtual ~Data() {} }; Context(); ~Context(); // Associates an owner (O) with its data (D) void add(const void* owner, Data* data); // O calls this when he knows its the end (O's destructor). // All instances of C are now aware that O is gone and its time to get rid // of all associated instances of D. static void purge (const void* owner); // This is called periodically in the application. It checks whether // O has called purge, and calls "delete D;" void refresh(); // Side note: sometimes O needs access to D Data *get (const void *owner); private: // Used for mapping owners (O) to data (D) std::map _data; }; // Here's an example of O class Mesh { public: ~Mesh() { Context::purge(this); } void init(Context& c) const { Data* data = new Data; // GL initialization here c.add(this, new Data); } void render(Context& c) const { Data* data = c.get(this); } private: // And here's an example of D struct Data : public Context::Data { ~Data() { glDeleteBuffers(1, &vbo); glDeleteTextures(1, &texture); } GLint vbo; GLint texture; }; }; P.S. If you're familiar with computer graphics and VR, I'm creating a class that separates an object's per-context data (e.g. OpenGL VBO IDs) from its per-application data (e.g. an array of vertices) and frees the per-context data at the appropriate time (when the matching rendering context is current).

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• Why no switch on pointers?

  - by meeselet

  For instance: #include <stdio.h> void why_cant_we_switch_him(void *ptr) { switch (ptr) { case NULL: printf("NULL!\n"); break; default: printf("%p!\n", ptr); break; } } int main(void) { void *foo = "toast"; why_cant_we_switch_him(foo); return 0; } gcc test.c -o test test.c: In function 'why_cant_we_switch_him': test.c:5: error: switch quantity not an integer test.c:6: error: pointers are not permitted as case values Just curious. Is this a technical limitation? EDIT People seem to think there is only one constant pointer expression. Is that is really true, though? For instance, here is a common paradigm in Objective-C (it is really only C aside from NSString, id and nil, which are merely a pointers, so it is still relevant — I just wanted to point out that there is, in fact, a common use for it, despite this being only a technical question): #include <stdio.h> #include <Foundation/Foundation.h> static NSString * const kMyConstantObject = @"Foo"; void why_cant_we_switch_him(id ptr) { switch (ptr) { case kMyConstantObject: // (Note that we are comparing pointers, not string values.) printf("We found him!\n"); break; case nil: printf("He appears to be nil (or NULL, whichever you prefer).\n"); break; default: printf("%p!\n", ptr); break; } } int main(void) { NSString *foo = @"toast"; why_cant_we_switch_him(foo); foo = kMyConstantObject; why_cant_we_switch_him(foo); return 0; } gcc test.c -o test -framework Foundation test.c: In function 'why_cant_we_switch_him': test.c:5: error: switch quantity not an integer test.c:6: error: pointers are not permitted as case values It appears that the reason is that switch only allows integral values (as the compiler warning said). So I suppose a better question would be to ask why this is the case? (though it is probably too late now.)

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• C++ Using a class template argument as a template argument for another type

  - by toefel

  Hey Everyone, I'm having this problem while writing my own HashTable. It all works, but when I try to templatize the thing, it gave me errors. I recreated the problem as follows: THIS CODE WORKS: typedef double Item; class A { public: A() { v.push_back(pair<string, Item>("hey", 5.0)); } void iterate() { for(Iterator iter = v.begin(); iter != v.end(); ++iter) cout << iter->first << ", " << iter->second << endl; } private: vector<pair<string, double> > v; typedef vector< pair<string, double> >::iterator Iterator; }; THIS CODE DOES NOT: template<typename ValueType> class B { public: B(){} void iterate() { for(Iterator iter = v.begin(); iter != v.end(); ++iter) cout << iter->first << ", " << iter->second << endl; } private: vector<pair<string, ValueType> > v; typedef vector< pair<string, ValueType> >::iterator Iterator; }; the error messages: g++ -O0 -g3 -Wall -c -fmessage-length=0 -omain.o ..\main.cpp ..\main.cpp:50: error: type std::vector<std::pair<std::string, ValueType>, std::allocator<std::pair<std::string, ValueType> > >' is not derived from typeB' ..\main.cpp:50: error: ISO C++ forbids declaration of `iterator' with no type ..\main.cpp:50: error: expected `;' before "Iterator" ..\main.cpp: In member function `void B::iterate()': ..\main.cpp:44: error: `Iterator' was not declared in this scope ..\main.cpp:44: error: expected `;' before "iter" ..\main.cpp:44: error: `iter' was not declared in this scope Does anybody know why this is happening? Thanks!

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• dynamically create element using javascript

  - by ajithperuva

  I need to create textbox dynamically when user click a link.And also i need to remove that textbox according to user decission.I am trying the following script. <script language="JavaScript" type="text/javascript"> var Dom = { get: function(el) { if (typeof el === 'string') { return document.getElementById(el); } else { return el; } }, add: function(el, dest) { var el = this.get(el); var dest = this.get(dest); dest.appendChild(el); }, remove: function(el) { var el = this.get(el); el.parentNode.removeChild(el); } }; var Event = { add: function() { if (window.addEventListener) { return function(el, type, fn) { Dom.get(el).addEventListener(type, fn, false); }; } else if (window.attachEvent) { return function(el, type, fn) { var f = function() { fn.call(Dom.get(el), window.event); }; Dom.get(el).attachEvent('on' + type, f); }; } }() }; Event.add(window, 'load', function() { var i = 0; Event.add('add-element', 'click', function() { var el = document.createElement('p'); el.innerHTML = '<br><input type="text">Remove(' + ++i + ')'; Dom.add(el, 'content'); Event.add(el, 'click', function(e) { Dom.remove(this); }); }); }); </script> <style> #add-element { cursor: pointer; } </style> <body> <div id="doc"> <p id="add-element">Add Elements</p> <div id="content"></div> </div> </body> It will create element and remove the element.But, it not allow me to enter text in newly created textbox( if i need).What is wrong with me.Please help to go forward...please

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• EXC_BAD_ACCESS when I change moviePlayer contentURL

  - by Bruno

  Hello, In few words, my application is doing that : 1) My main view (MovieListController) has some video thumbnails and when I tap on one, it displays the moviePlayer (MoviePlayerViewController) : MovieListController.h : @interface MoviePlayerViewController : UIViewController <UITableViewDelegate>{ UIView *viewForMovie; MPMoviePlayerController *player; } @property (nonatomic, retain) IBOutlet UIView *viewForMovie; @property (nonatomic, retain) MPMoviePlayerController *player; - (NSURL *)movieURL; @end MovieListController.m : MoviePlayerViewController *controllerTV = [[MoviePlayerViewController alloc] initWithNibName:@"MoviePlayerViewController" bundle:nil]; controllerTV.delegate = self; controllerTV.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; [self presentModalViewController: controllerTV animated: YES]; [controllerTV release]; 2) In my moviePlayer, I initialize the video I want to play MoviePlayerViewController.m : @implementation MoviePlayerViewController @synthesize player; @synthesize viewForMovie; - (void)viewDidLoad { NSLog(@"start"); [super viewDidLoad]; self.player = [[MPMoviePlayerController alloc] init]; self.player.view.frame = self.viewForMovie.bounds; self.player.view.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight; [self.viewForMovie addSubview:player.view]; self.player.contentURL = [self movieURL]; } - (void)dealloc { NSLog(@"dealloc TV"); [player release]; [viewForMovie release]; [super dealloc]; } -(NSURL *)movieURL { NSBundle *bundle = [NSBundle mainBundle]; NSString *moviePath = [bundle pathForResource:@"FR_Tribord_Surf camp_100204" ofType:@"mp4"]; if (moviePath) { return [NSURL fileURLWithPath:moviePath]; } else { return nil; } } - It's working good, my movie is display My problem : When I go back to my main view : - (void) returnToMap: (MoviePlayerViewController *) controller { [self dismissModalViewControllerAnimated: YES]; } And I tap in a thumbnail to display again the moviePlayer (MoviePlayerViewController), I get a *Program received signal: “EXC_BAD_ACCESS”.* In my debugger I saw that it's stopping on the thread "main" : // // main.m // MoviePlayer // // Created by Eric Freeman on 3/27/10. // Copyright Apple Inc 2010. All rights reserved. // #import <UIKit/UIKit.h> int main(int argc, char *argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; int retVal = UIApplicationMain(argc, argv, nil, nil); //EXC_BAD_ACCESS [pool release]; return retVal; } If I comment self.player.contentURL = [self movieURL]; it's working, but when I let it, iI have this problem. I read that it's due to null pointer or memory problem but I don't understand why it's working the first time and not the second time. I release my object in dealloc method. Thanks for your help ! Bruno.

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• FFMPEG-PHP Windows "Can't open movie file"

  - by bah

  Hi, ffmpeg extension is loaded as it is shown at phpinfo(), my file and script are at the same location, but I'm still getting this error. Warning: Can't open movie file Untitled.avi in C:\xampp\htdocs\skelbiu\fetch.php on line 4 Fatal error: Call to a member function getDuration() on a non-object in C:\xampp\htdocs\skelbiu\fetch.php on line 5 My script: extension_loaded('ffmpeg') or die('Error in loading ffmpeg'); $ffmpegInstance = new ffmpeg_movie('Untitled.avi'); echo "getDuration: " . $ffmpegInstance->getDuration() . "getFrameCount: " . $ffmpegInstance->getFrameCount() . "getFrameRate: " . $ffmpegInstance->getFrameRate() . "getFilename: " . $ffmpegInstance->getFilename() . "getComment: " . $ffmpegInstance->getComment() . "getTitle: " . $ffmpegInstance->getTitle() . "getAuthor: " . $ffmpegInstance->getAuthor() . "getCopyright: " . $ffmpegInstance->getCopyright() . "getArtist: " . $ffmpegInstance->getArtist() . "getGenre: " . $ffmpegInstance->getGenre() . "getTrackNumber: " . $ffmpegInstance->getTrackNumber() . "getYear: " . $ffmpegInstance->getYear() . "getFrameHeight: " . $ffmpegInstance->getFrameHeight() . "getFrameWidth: " . $ffmpegInstance->getFrameWidth() . "getPixelFormat: " . $ffmpegInstance->getPixelFormat() . "getBitRate: " . $ffmpegInstance->getBitRate() . "getVideoBitRate: " . $ffmpegInstance->getVideoBitRate() . "getAudioBitRate: " . $ffmpegInstance->getAudioBitRate() . "getAudioSampleRate: " . $ffmpegInstance->getAudioSampleRate() . "getVideoCodec: " . $ffmpegInstance->getVideoCodec() . "getAudioCodec: " . $ffmpegInstance->getAudioCodec() . "getAudioChannels: " . $ffmpegInstance->getAudioChannels() . "hasAudio: " . $ffmpegInstance->hasAudio(); I'm using php 5.2.9 (XAMPP 1.7.1), Windows 7. Thanks in advance!

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• How to access static members in a Velocity template?

  - by matt b

  I'm not sure if there is a way to do this in Velocity or not: I have a User POJO which a property named Status, which looks like an enum (but it is not, since I am stuck on Java 1.4), the definition looks something like this: public class User { // default status to User private Status status = Status.USER; public void setStatus(Status status) { this.status = status; } public Status getStatus() { return status; } And Status is a static inner class: public static final class Status { private String statusString; private Status(String statusString) { this.statusString = statusString; } public final static Status USER = new Status("user"); public final static Status ADMIN = new Status("admin"); public final static Status STATUS_X = new Status("blah"); //.equals() and .hashCode() implemented as well } With this pattern, a user status can easily be tested in a conditional such as if(User.Status.ADMIN.equals(user.getStatus())) ... ... without having to reference any constants for the status ID, any magic numbers, etc. However, I can't figure out how to test these conditionals in my Velocity template with VTL. I'd like to just print a simple string based upon the user's status, such as: Welcome <b>${user.name}</b>! <br/> <br/> #if($user.status == com.company.blah.User.Status.USER) You are a regular user #elseif($user.status == com.company.blah.User.Status.ADMIN) You are an administrator #etc... #end But this throws an Exception that looks like org.apache.velocity.exception.ParseErrorException: Encountered "User" at webpages/include/dashboard.inc[line 10, column 21] Was expecting one of: "[" ... From the VTL User Guide, there is no mention of accessing a Java class/static member directly in VTL, it appears that the right hand side (RHS) of a conditional can only be a number literal, string literal, property reference, or method reference. So is there any way that I can access static Java properties/references in a Velocity template? I'm aware that as a workaround, I could embed the status ID or some other identifier as a reference in my controller (this is a web MVC application using Velocity as the View technology), but I strongly do not want to embed any magic numbers or constants in the view layer.

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