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  • Simplest way to automatically alter "const" value in Java during compile time

    - by Michael Mao
    Hi all: This is a question corresponds to my uni assignment so I am very sorry to say I cannot adopt any one of the following best practices in a short time -- you know -- assignment is due tomorrow :( link to Best way to alter const in Java on StackOverflow Basically the only task (I hope so) left for me is the performance tuning. I've got a bunch of predefined "const" values in my single-class agent source code like this: //static final values private static final long FT_THRESHOLD = 400; private static final long FT_THRESHOLD_MARGIN = 50; private static final long FT_SMOOTH_PRICE_IDICATOR = 20; private static final long FT_BUY_PRICE_MODIFIER = 0; private static final long FT_LAST_ROUNDS_STARTTIME = 90; private static final long FT_AMOUNT_ADJUST_MODIFIER = 5; private static final long FT_HISTORY_PIRCES_LENGTH = 10; private static final long FT_TRACK_DURATION = 5; private static final int MAX_BED_BID_NUM_PER_AUC = 12; I can definitely alter the values manually and then compile the code to give it another go around. But the execution time for a thorough "statistic analysis" usually requires over 2000 times of execution, which will typically lasts more than half an hour on my own laptop... So I hope there is a way to alter values using other ways than dig into the source code to change the "const" values there, so I can automatically distributed compiled code to other people's PC and let them run the statistic analysis instead. One other reason for a automatically value adjustment is that I can try using my own agent to defeat itself by choosing different "const" values. Although my values are derived from previous history and statistical results, they are far from the most optimized values. I hope there is a easy way so I can quickly adopt that so to have a good sleep tonight while the computer does everything for me... :) Any hints on this sort of stuff? Any suggestion is welcomed and much appreciated.

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  • How does asp.net MVC remember my incorrect values on postback?

    - by Michel
    This is working, but how??? I have a controller action for a post: [AcceptVerbs(HttpVerbs.Post )] public ActionResult Edit(Person person) { bool isvalid = ModelState.IsValid; etc. The Person object has a property BirthDate, type DateTime. When i enter some invalid data in the form, say 'blabla' which is obvious not a valid Datetime, it fills all the (other) Person properties with the correct data and the BirthDate property with a new blank DateTime. The bool isvalid has the value 'false'. So far so good. Then i do this: return View(p); and in the view i have this: <%= Html.TextBox("BirthDate", String.Format("{0:g}", Model.BirthDate)) %> <%= Html.ValidationMessage("BirthDate", "*") %> Ant there it comes: i EXPECTED the model to contain the new, blank DateTime because i didn't put any new data in. Second, when the View displays something, it must be a DateTime, because Model.BirthDate can't hold anything but a DateTime. But to my surprise, it shows a textbox with the 'blabla' value! (and the red * behind it) Which ofcourse is nice because the user can seee what he typed wrong, but how can that (blabla)string be transferred to the View in a DateTime field?

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  • How do I search a NTEXT column for XML attributes and update the values? MS SQL 2005

    - by Alan
    Duplicate: this exact question was asked by the same author in http://stackoverflow.com/questions/1221583/how-do-i-update-a-xml-string-in-an-ntext-column-in-sql-server. Please close this one and answer in the original question. I have a SQL table with 2 columns. ID(int) and Value(ntext) The value rows have all sorts of xml strings in them. ID Value -- ------------------ 1 <ROOT><Type current="TypeA"/></ROOT> 2 <XML><Name current="MyName"/><XML> 3 <TYPE><Colour current="Yellow"/><TYPE> 4 <TYPE><Colour current="Yellow" Size="Large"/><TYPE> 5 <TYPE><Colour current="Blue" Size="Large"/><TYPE> 6 <XML><Name current="Yellow"/><XML> How do I: A. List the rows where <TYPE><Colour current="Yellow", bearing in mind that there is an entry <XML><Name current="Yellow"/><XML> B. Modify the rows that contain <TYPE><Colour current="Yellow" to be <TYPE><Colour current="Purple" Thanks! 4 your help

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  • Why would I be seeing execution timeouts when setting $_SESSION values?

    - by Kev
    I'm seeing the following errors in my PHP error logs: PHP Fatal error: Maximum execution time of 60 seconds exceeded in D:\sites\s105504\www\index.php on line 3 PHP Fatal error: Maximum execution time of 60 seconds exceeded in D:\sites\s105504\www\search.php on line 4 The lines in question are: index.php: 01 <?php 02 session_start(); 03 ob_start(); 04 error_reporting(E_All); 05 $_SESSION['nav'] = "range"; // <-- Error generated here search.php 01 <?php 02 03 session_start(); 04 $_SESSION['nav'] = "range"; 05 $_SESSION['navselected'] = 21; // <-- Error generated here Would it really take as long as 60+ seconds to assign a $_SESSION[] value? The platform is: Windows 2003 SP2 + IIS6 FastCGI for Windows 2003 (original RTM build) PHP 5.2.6 Non thread-safe build There aren't any issues with session data files being cleared up on the server as sessions expire. The oldest sess_XXXXXXXXXXXXXX file I'm seeing is around 2 hours old. There are no disk timeouts evident in the event logs or other such disk health issues that might suggest difficulty creating session data files. The site is also on a server that isn't under heavy load. The site is busy but not being hammered and is very responsive. It's just that we get these errors, three or four in a row, every three or four hours. I should also add that I'm not the original developer of this code and that it belongs to a customer who's developer has long since departed.

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  • How do you read data from a ADODB stream in ASP as byte values?

    - by user89691
    I have an ASP routine that gets a binary file's contents and writes it to a stream. The intention is to read it from the stream and process it st the server. So I have: ResponseBody = SomeRequest (SomeURL) ; var BinaryInputStream = Server.CreateObject ("ADODB.Stream") ; BinaryInputStream.Type = 1 ; // binary BinaryInputStream.Open ; BinaryInputStream.Write (ResponseBody) ; BinaryInputStream.Position = 0 ; var DataByte = BinaryInputStream.Read (1) ; Response.Write (typeof (DataByte)) ; // displays "unknown" How do I get the byte value of the byte I have just read from the stream? Asc () and byte () don't work (JScript) TIA

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  • In Drupal, how to change the values passed to Pathauto?

    - by Vinicius Pinto
    I have Pathauto configured to generate an alias based on the title of a node, for a specific content type. The problem is that I want to make small changes in this title before Pathauto uses it to generate the alias. The first comment in this post suggests the use of hook_token_values, but I couldn't really understand how to use it, even after reading the docs. In my tests, when I implement this hook, the alias generated is always "array", which means I'm missing something. Any help? Thanks.

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  • how to include in web.config an external mydll.config file and read its values?

    - by firepol
    Hi, I found this answer about external configuration files. I'm trying to do a similar thing. I have a small webapplication called StatsGen I want to include in other projects, and for convenience I'd like to have the settings inside the bin folder, in a config file with an appropriate name, in my case: StatsGen.config. So I've put these line in the web.config (as explained in the answer I mentioned above): <configSections> <section name="StatsGenSettings" restartOnExternalChanges="true" type="System.Configuration.NameValueFileSectionHandler" /> <!--sectionGroups--> </configSections> <StatsGenSettings configSource="StatsGen.config"></StatsGenSettings> <!--and here comes the rest... appSettings etc.--> Inside the bin folder, I created a StatsGen.xml file, then renamed it to StatsGen.config. It looks like this: <?xml version="1.0" encoding="utf-8" ?> <StatsGenSettings> <add key="Password" value="myStatsPass" /> <add key="ConnectionString" value="Server=mydbsrv;Database=myDB;User ID=myUser;Password=myPass" /> </StatsGenSettings> I created an Helper class, as suggested in the answer. In the Page_Load of my default.aspx.cs file, I've put: goodPassword = StatsGenSettings.Instance["Password"]; When I load my page, I get this error: The type initializer for 'StatsGen.Helpers.StatsGenSettings' threw an exception. I've tried to exlude the helper and just to get access to the key, like this: NameValueCollection _settings = ConfigurationManager.GetSection("StatsGenSettings") as NameValueCollection; And I get this error: Unable to open configSource file 'StatsGen.config'. (C:\Users\pbo\Documents\Visual Studio 2010\Projects\StatsGen\StatsGen\web.config line 21) At line 21 I just have this, as explained above: <StatsGenSettings configSource="StatsGen.config"></StatsGenSettings> So now I'm wondering, what's wrong? Some detailed help would be cool... like: where exactly should I declare the StatsGenSettings element inside the web.config? It was not specified in the answer I've found... or what else am I doing wrong? Thanks for letting me know...

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  • Why doesn't negative values for the second index in a jagged array work in Python?

    - by univerio
    For example, if I have the following (data from Project Euler): s = [[75], [95, 64], [17, 47, 82], [18, 35, 87, 10], [20, 4, 82, 47, 65], [19, 1, 23, 75, 3, 34], [88, 2, 77, 73, 7, 63, 67], [99, 65, 4, 28, 6, 16, 70, 92], [41, 41, 26, 56, 83, 40, 80, 70, 33], [41, 48, 72, 33, 47, 32, 37, 16, 94, 29], [53, 71, 44, 65, 25, 43, 91, 52, 97, 51, 14], [70, 11, 33, 28, 77, 73, 17, 78, 39, 68, 17, 57], [91, 71, 52, 38, 17, 14, 91, 43, 58, 50, 27, 29, 48], [63, 66, 4, 68,89, 53, 67, 30, 73, 16, 69, 87, 40, 31], [4, 62, 98, 27, 23, 9, 70, 98, 73, 93, 38, 53, 60, 4, 23]] Why does s[1:][:-1] give me the same thing as s[1:] instead of (what I want) [s[i][:-1] for i in range(1,len(s))]. In other words, why does Python ignore my second index?

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  • Turn Excel spreadsheet into a formula

    - by ?????? ??????????
    I have an Excel spreadsheet that has a complex computation that is not trivial to turn into a macro or a single-cell formula. The spreadsheet has a about 10 different inputs (values a human enters in different cells of the spreadsheet) and then it outputs 5 independent calculations (in different 5 cells) based on that input. There calculation is using some pre-entered data in the spreadsheet (about 100 different constants) and doing some look-ups on them. Now I would like to use this whole spreadsheet as a formula on a different spreadsheet to calculate a set of input values and produce the corresponding set of output values. Imagine this as creating different table with 10 columns for the input variables and 5 columns for the outputs, then copying each input into the other spreadsheet and copying back the output in the results table. For instance: - A1, A2, A3,... A10 are cells where someone enters values - through a series of calculations B1, B2, B3, B4 and B5 are updated with some formulas Can I use the whole series of calculations from A1..A10 into B1..B5 without creating one massive huge formula or a VBA macro? I want to have a set of input values in 100 rows from A100, B100, C100,... J100 onward. Then do some Excel magic that will: 1. copy the values from A100...J100 into A1 to A10 2. wait for the result to appear in B1 to B5 3. copy the values from B1 to B5 into K100 to O100 4. repeat steps 1 to 3 for all rows from 100 to 150

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  • How to give default values for the sum, count if no data exist in mysql query which uses group by?

    - by Salil
    I am using following query which works fine for me except one problem SELECT f.period as month, sum(p.revenue * ((100-q.rate)/100)) as revenue ,count(distinct q.label) as tot_stmt FROM files f, reports p, rates q,albums a where f.period in ('2010-06-01','2010-05-01','2010-04-01','2010-03-01') and f.period_closed = true and q.period = f.period and a.id = q.album_id and p.file_id = f.id and p.upc = a.upc and p.revenue is not null GROUP BY month ORDER BY month DESC O/P = month            revenue     tot_stmt 2010-06-01     10.00         2 2010-05-01     340.47       2 I want result like following month            revenue     tot_stmt 2010-06-01     10.00         2 2010-05-01     340.47       2 2010-04-01     0.00           0 2010-03-01     0.00           0 Regards, Salil Gaikwad

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  • Is it possible to call a JavaScript function using an array of values as arguments ?

    - by Moshe Levine
    I'm looking for another way of doing the following: function call_any_function(func, parameters){ // func => any given function if(parameters.length==0){ func(); } if(parameters.length==1){ func(parameters[0]); } if(parameters.length==2){ func(parameters[0], parameters[1]); } if(parameters.length==3){ func(parameters[0], parameters[1], parameters[2]); } if(parameters.length==4){ func(parameters[0], parameters[1], parameters[2], parameters[3]); } // ... and so on }; It seems basic but I couldn't find an answer. Any ideas?

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  • Why does this JavaScript not correctly update input values?

    - by dmanexe
    I have two input fields, and without changing their names (i.e., I have to use the name with the brackets), how do I make this javascript code work? <script> function calc_concreteprice(mainform) { var oprice; var ototal; oprice = (eval(mainform.'estimate[concrete][sqft]'.value) * eval(mainform.'estimate[concrete][price]'.value)); ototal = (oprice); mainform.'estimate[concrete][quick_total]'.value = ototal; } </script> Here's the HTML of the input area. <tr> <td>Concrete Base Price</td> <td><input type="text" name="concrete[concrete][price]" value="" class="item_mult" onBlur="calc_concreteprice(document.forms.mainform);" /> per SF <strong>times</strong> <input type="text" name="concrete[concrete][sqft]" value="" class="item_mult" onBlur="calc_concreteprice(document.forms.mainform);" /> SF</td> <td> = <input type="text" name="concrete[concrete][quick_total]" value="" /></td> </tr> I know I can get it working by changing_the_input_name_with_underscores but I need to have the names with the brackets (storing the form contents in an array).

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  • How do I delete a [sub]hash based off of the keys/values of another hash?

    - by Zack
    Lets assume I have two hashes. One of them contains a set of data that only needs to keep things that show up in the other hash. e.g. my %hash1 = ( test1 => { inner1 => { more => "alpha", evenmore => "beta" } }, test2 => { inner2 => { more => "charlie", somethingelse => "delta" } }, test3 => { inner9999 => { ohlookmore => "golf", somethingelse => "foxtrot" } } ); my %hash2 = ( major=> { test2 => "inner2", test3 => "inner3" } ); What I would like to do, is to delete the whole subhash in hash1 if it does not exist as a key/value in hash2{major}, preferably without modules. The information contained in "innerX" does not matter, it merely must be left alone (unless the subhash is to be deleted then it can go away). In the example above after this operation is preformed hash1 would look like: my %hash1 = ( test2 => { inner2 => { more => "charlie", somethingelse => "delta" } }, ); It deletes hash1{test1} and hash1{test3} because they don't match anything in hash2. Here's what I've currently tried, but it doesn't work. Nor is it probably the safest thing to do since I'm looping over the hash while trying to delete from it. However I'm deleting at the each which should be okay? This was my attempt at doing this, however perl complains about: Can't use string ("inner1") as a HASH ref while "strict refs" in use at while(my ($test, $inner) = each %hash1) { if(exists $hash2{major}{$test}{$inner}) { print "$test($inner) is in exists.\n"; } else { print "Looks like $test($inner) does not exist, REMOVING.\n"; #not to sure if $inner is needed to remove the whole entry delete ($hash1{$test}{$inner}); } }

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  • Database Design: A proper table design for large number of column values.

    - by Jake
    I wish to perform an experiment many different times. After every trial, I am left with a "large" set of output statistics -- let's say, 1000. I would like to store the outputs of my experiments in a table, but what's the best way...? Option 1 Have a table with 1000 columns. Seems like a bad idea. What if the number of statistics one day exceeds the maximum number of columns? Option 2 Have a table with three columns. Let's say, ID, StatisticType, and StatisticValue. That way, you can have as many statistics as you want. However, reading a single experiments statistics becomes more complicated. Moreover, what if different statistics are different data types?? Any suggestions?

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  • How to automatically read in calculated values with PHPExcel?

    - by Edward Tanguay
    I have the following Excel file: I read it in by looping over every cell and getting the value with getCell(...)->getValue(): $highestColumnAsLetters = $this->objPHPExcel->setActiveSheetIndex(0)->getHighestColumn(); //e.g. 'AK' $highestRowNumber = $this->objPHPExcel->setActiveSheetIndex(0)->getHighestRow(); $highestColumnAsLetters++; for ($row = 1; $row < $highestRowNumber + 1; $row++) { $dataset = array(); for ($columnAsLetters = 'A'; $columnAsLetters != $highestColumnAsLetters; $columnAsLetters++) { $dataset[] = $this->objPHPExcel->setActiveSheetIndex(0)->getCell($columnAsLetters.$row)->getValue(); if ($row == 1) { $this->column_names[] = $columnAsLetters; } } $this->datasets[] = $dataset; } However, although it reads in the data fine, it reads in the calculations literally: I understand from discussions like this one that I can use getCalculatedValue() for calculated cells. The problem is that in the Excel sheets I am importing, I do not know beforehand which cells are calculated and which are not. Is there a way for me to read in the value of a cell in a way that automatically gets the value if it has a simple value and gets the result of the calculation if it is a calculation?

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  • PHP - My array returns NULL values when placed in a function, but works fine outside of the function

    - by orbit82
    Okay, let me see if I can explain this. I am making a newspaper WordPress theme. The theme pulls posts from categories. The front page shows multiple categories, organized as "newsboxes". Each post should show up only ONCE on the front page, even if said post is in two or more categories. To prevent posts from duplicating on the front page, I've created an array that keeps track of the individual post IDs. When a post FIRST shows up on the front page, its ID gets added to the array. Before looping through the posts for each category, the code first checks the array to see which posts have ALREADY been displayed. OK, so now remember how I said earlier that the front page shows multiple categories organized as "newsboxes"? Well, these newsboxes are called onto the front page using PHP includes. I have 6 newsboxes appearing on the front page, and the code to call them is EXACTLY the same. I didn't want to repeat the same code 6 times, so I put all of the inclusion code into a function. The function works, but the only problem is that it screws up the duplicate posts code I mentioned earlier. The posts all repeat. Running a var_dump on the $do_not_duplicate variable returns an array with null indices. Everything works PERFECTLY if I don't put the code inside a function, but once I do put them in a function it's like the arrays aren't even connecting with the posts. Here is the code with the arrays. The key variables in question here include $do_not_duplicate[] = $post-ID, $do_not_duplicate and 'post__not_in' = $do_not_duplicate <?php query_posts('cat='.$settings['cpress_top_story_category'].'&posts_per_page='.$settings['cpress_number_of_top_stories'].'');?> <?php if (have_posts()) : ?> <!--TOP STORY--> <div id="topStory"> <?php while ( have_posts() ) : the_post(); $do_not_duplicate[] = $post->ID; ?> <a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_post_thumbnail('top-story-thumbnail'); ?></a> <h2 class="extraLargeHeadline"><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2> <div class="topStory_author"><?php cpress_show_post_author_byline(); ?></div> <div <?php post_class('topStory_entry') ?> id="post-<?php the_ID(); ?>"> <?php if($settings['cpress_excerpt_or_content_top_story_newsbox'] == "content") { the_content(); ?><a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>"><span class="read_more"><?php echo $settings['cpress_more_text']; ?></span></a> <?php } else { the_excerpt(); ?><a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>"><span class="read_more"><?php echo $settings['cpress_more_text']; ?></span></a> <?php }?> </div><!--/topStoryentry--> <div class="topStory_meta"><?php cpress_show_post_meta(); ?></div> <?php endwhile; wp_reset_query(); ?> <?php if(!$settings['cpress_hide_top_story_more_stories']) { ?> <!--More Top Stories--><div id="moreTopStories"> <?php $category_link = get_category_link(''.$settings['cpress_top_story_category'].''); ?> <?php if (have_posts()) : ?> <?php query_posts( array( 'cat' => ''.$settings['cpress_top_story_category'].'', 'posts_per_page' => ''.$settings['cpress_number_of_more_top_stories'].'', 'post__not_in' => $do_not_duplicate ) ); ?> <h4 class="moreStories"> <?php if($settings['cpress_make_top_story_more_stories_link']) { ?> <a href="<?php echo $category_link; ?>" title="<?php echo strip_tags($settings['cpress_top_story_more_stories_text']);?>"><?php echo strip_tags($settings['cpress_top_story_more_stories_text']);?></a><?php } else { echo strip_tags($settings['cpress_top_story_more_stories_text']); } ?> </h4> <ul> <?php while( have_posts() ) : the_post(); $do_not_duplicate[] = $post->ID; ?> <li><h2 class="mediumHeadline"><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2> <?php if(!$settings['cpress_hide_more_top_stories_excerpt']) { ?> <div <?php post_class('moreTopStory_postExcerpt') ?> id="post-<?php the_ID(); ?>"><?php if($settings['cpress_excerpt_or_content_top_story_newsbox'] == "content") { the_content(); ?><a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>"><span class="read_more"><?php echo $settings['cpress_more_text']; ?></span></a> <?php } else { the_excerpt(); ?> <a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>"><span class="read_more"><?php echo $settings['cpress_more_text']; ?></span></a> <?php }?> </div><?php } ?> <div class="moreTopStory_postMeta"><?php cpress_show_post_meta(); ?></div> </li> <?php endwhile; wp_reset_query(); ?> </ul> <?php endif;?> </div><!--/moreTopStories--> <?php } ?> <?php echo(var_dump($do_not_duplicate)); ?> </div><!--/TOP STORY--> <?php endif; ?> And here is the code that includes the newsboxes onto the front page. This is the code I'm trying to put into a function to avoid duplicating it 6 times on one page. function cpress_show_templatebitsf($tbit_num, $tbit_option) { global $tbit_path; global $shortname; $settings = get_option($shortname.'_options'); //display the templatebits (usually these will be sidebars) for ($i=1; $i<=$tbit_num; $i++) { $tbit = strip_tags($settings[$tbit_option .$i]); if($tbit !="") { include_once(TEMPLATEPATH . $tbit_path. $tbit.'.php'); } //if }//for loop unset($tbit_option); } I hope this makes sense. It's kind of a complex thing to explain but I've tried many things to fix it and have had no luck. I'm stumped. I'm hoping it's just some little thing I'm overlooking because it seems like it shouldn't be such a problem.

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  • How to store some of the entity's values in another table using hibernate?

    - by nimcap
    Hi guys, is there a simple way to persist some of the fields in another class and table using hibernate. For example, I have a Person class with name, surname, email, address1, address2, city, country fields. I want my classes to be: public class Person { private String name; private String surname; private String email; private Address address; // .. } public class Address { private Person person; // to whom this belongs private String address1; private String address2; private String city; private Address country; // .. } and I want to store Address in another table. What is the best way to achieve this? Edit: I am using annotations. It does not have to be the way I described, I am looking for best practices. PS. If there is a way to make Address immutable (to use as a value object) that is even better, or maybe not because I thought everything from wrong perspective :)

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  • [Wordpress] How do I return values from custom created meta box?

    - by Steven
    I've just followed this example from Wordpress and I have successfully added an extra Meta Box in Post interface, and the value is stored in DB. Now my question is, how can I retrieve and display the content of this meta box? I'm trying the following code: $intro = get_post_meta($post->ID, 'post_intro', true); echo $intro; But I get nada. What am I doing wrong? And while I'm here, does anybody know if I can place this extra meta box above the default text box in Wordpress post page?

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  • How do I use Eval() to reference values in a SortedDictionary in an asp Repeater?

    - by MatthewMartin
    I thought I was clever to switch from the memory intensive DataView to SortedDictionary as a memory efficient sortable data structure. Now I have no idea how get the key and value out of the datasource in the <%# or Eval() expressions. SortedDictionary<int, string> data = RetrieveNames(); rCurrentTeam.DataSource = data; rCurrentTeam.DataBind(); <asp:Repeater ID="rNames" runat="server"> <ItemTemplate> <asp:Label ID="lblName" runat="server" Text='<%# Eval("what?") %>' /> </ItemTemplate> </asp:Repeater> Any suggestions?

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  • Why does Microsoft advise against readonly fields with mutable values?

    - by Weeble
    In the Design Guidelines for Developing Class Libraries, Microsoft say: Do not assign instances of mutable types to read-only fields. The objects created using a mutable type can be modified after they are created. For example, arrays and most collections are mutable types while Int32, Uri, and String are immutable types. For fields that hold a mutable reference type, the read-only modifier prevents the field value from being overwritten but does not protect the mutable type from modification. This simply restates the behaviour of readonly without explaining why it's bad to use readonly. The implication appears to be that many people do not understand what "readonly" does and will wrongly expect readonly fields to be deeply immutable. In effect it advises using "readonly" as code documentation indicating deep immutability - despite the fact that the compiler has no way to enforce this - and disallows its use for its normal function: to ensure that the value of the field doesn't change after the object has been constructed. I feel uneasy with this recommendation to use "readonly" to indicate something other than its normal meaning understood by the compiler. I feel that it encourages people to misunderstand the meaning of "readonly", and furthermore to expect it to mean something that the author of the code might not intend. I feel that it precludes using it in places it could be useful - e.g. to show that some relationship between two mutable objects remains unchanged for the lifetime of one of those objects. The notion of assuming that readers do not understand the meaning of "readonly" also appears to be in contradiction to other advice from Microsoft, such as FxCop's "Do not initialize unnecessarily" rule, which assumes readers of your code to be experts in the language and should know that (for example) bool fields are automatically initialised to false, and stops you from providing the redundancy that shows "yes, this has been consciously set to false; I didn't just forget to initialize it". So, first and foremost, why do Microsoft advise against use of readonly for references to mutable types? I'd also be interested to know: Do you follow this Design Guideline in all your code? What do you expect when you see "readonly" in a piece of code you didn't write?

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  • Best way to check for null values in Java?

    - by Arty-fishL
    I need to check whether the function of an object returns true or false in Java, but that object may be null, so obviously then the function would throw a NullPointerException. This means I need to check if the object is null before checking the value of the function. What is the best way to go about this? I've listed some methods I considered, I just want to know the most sensible one, the one that is best programming practice for Java (opinion?). // method 1 if (foo != null) { if (foo.bar()) { etc... } } // method 2 if (foo != null ? foo.bar() : false) { etc... } // method 3 try { if (foo.bar()) { etc... } } catch (NullPointerException e) { } // method 4 // would this work all the time, would it still call foo.bar()? if (foo != null && foo.bar()) { etc... }

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