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  • How can I make nested string splits?

    - by Statement
    I have what seemed at first to be a trivial problem but turned out to become something I can't figure out how to easily solve. I need to be able to store lists of items in a string. Then those items in turn can be a list, or some other value that may contain my separator character. I have two different methods that unpack the two different cases but I realized I need to encode the contained value from any separator characters used with string.Split. To illustrate the problem: string[] nested = { "mary;john;carl", "dog;cat;fish", "plainValue" } string list = string.Join(";", nested); string[] unnested = list.Split(';'); // EEK! returns 7 items, expected 3! This would produce a list "mary;john;carl;dog;cat;fish;plainValue", a value I can't split to get the three original nested strings from. Indeed, instead of the three original strings, I'd get 7 strings on split and this approach thus doesn't work at all. What I want is to allow the values in my string to be encoded so I can unpack/split the contents just the way before I packed/join them. I assume I might need to go away from string.Split and string.Join and that is perfectly fine. I might just have overlooked some useful class or method. How can I allow any string values to be packed / unpacked into lists? I prefer neat, simple solutions over bulky if possible. For the curious mind, I am making extensions for PlayerPrefs in Unity3D, and I can only work with ints, floats and strings. Thus I chose strings to be my data carrier. This is why I am making this nested list of strings.

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  • Java-Eclipse-Spring 3.1 - the fastest way to get familiar with this set

    - by Leron
    I, know almost all of you at some point of your life as a programmer get to the point where you know (more or less) different technologies/languages/IDEs and a times come when you want to get things together and start using them once - more efficient and second - more closely to the real life situation where in fact just knowing Java, or some experience with Eclipse doesn't mean nothing, and what makes you a programmer worth something is the ability to work with the combination of 2 or more combinations. Having this in mind here is my question - what do you think is the optimal way of getting into Java+Eclipse+Spring3.1 world. I've read, and I've read a lot. I started writing real code but almost every step is discovering the wheel again and again, wondering how to do thing you know are some what trivial, but you've missed that one article where this topic was discussed and so on. I don't mind for paying for a good tutorial like for example, after a bit of research I decided that instead of losing a lot of time getting the different parts together I'd rather pay for the videos in http://knpuniversity.com/screencast/starting-in-symfony2-tutorial and save myself a lot of time (I hope) and get as fast as possible to writing a real code instead of wondering what do what and so on. But I find it much more difficult to find such sources of info especially when you want something more specific as me and that's the reason to ask this question. I know a lot of you go through the hard way, and I won't give up if I have to do the same, but to be honest I really hope to get post with good tutorials on the subject (paid or not) because in my situation time is literally money. Thanks Leron

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  • SQL-Server: Is there an equivalent of a trigger for general stored procedure execution

    - by Arj
    Hi All, Hope you can help. Is there a way to reliably detect when a stored proc is being run on SQL Server without altering the SP itself? Here's the requirement. We need to track users running reports from our enterprise data warehouse as the core product we use doesn't allow for this. Both core product reports and a slew of in-house ones we've added all return their data from individual stored procs. We don't have a practical way of altering the parts of the product webpages where reports are called from. We also can't change the stored procs for the core product reports. (It would be trivial to add a logging line to the start/end of each of our inhouse ones). What I'm trying to find therefore, is whether there's a way in SQL Server (2005 / 2008) to execute a logging stored proc whenever any other stored procedure runs, without altering those stored procedures themselves. We have general control over the SQL Server instance itself as it's local, we just don't want to change the product stored procs themselves. Any one have any ideas? Is there a kind of "stored proc executing trigger"? Is there an event model for SQL Server that we can hook custom .Net code into? (Just to discount it from the start, we want to try and make a change to SQL Server rather than get into capturing the report being run from the products webpages etc) Thoughts appreciated Thanks

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  • Is it a good idea to use an integer column for storing US ZIP codes in a database?

    - by Yadyn
    From first glance, it would appear I have two basic choices for storing ZIP codes in a database table: Text (probably most common), i.e. char(5) or varchar(9) to support +4 extension Numeric, i.e. 32-bit integer Both would satisfy the requirements of the data, if we assume that there are no international concerns. In the past we've generally just gone the text route, but I was wondering if anyone does the opposite? Just from brief comparison it looks like the integer method has two clear advantages: It is, by means of its nature, automatically limited to numerics only (whereas without validation the text style could store letters and such which are not, to my knowledge, ever valid in a ZIP code). This doesn't mean we could/would/should forgo validating user input as normal, though! It takes less space, being 4 bytes (which should be plenty even for 9-digit ZIP codes) instead of 5 or 9 bytes. Also, it seems like it wouldn't hurt display output much. It is trivial to slap a ToString() on a numeric value, use simple string manipulation to insert a hyphen or space or whatever for the +4 extension, and use string formatting to restore leading zeroes. Is there anything that would discourage using int as a datatype for US-only ZIP codes?

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  • What are the elegant ways to do MixIns in Python?

    - by Slava Vishnyakov
    I need to find an elegant way to do 2 kinds of MixIns. First: class A(object): def method1(self): do_something() Now, a MixInClass should make method1 do this: do_other() - A.method1() - do_smth_else() - i.e. basically "wrap" the older function. I'm pretty sure there must exist a good solution to this. Second: class B(object): def method1(self): do_something() do_more() In this case, I want MixInClass2 to be able to inject itself between do_something() and do_more(), i.e.: do_something() - MixIn.method1 - do_more(). I understand that probably this would require modifying class B - that's ok, just looking for simplest ways to achieve this. These are pretty trivial problems and I actually solved them, but my solution is tainted. Fisrt one by using self._old_method1 = self.method1(); self.method1() = self._new_method1(); and writing _new_method1() that calls to _old_method1(). Problem: multiple MixIns will all rename to _old_method1 and it is inelegant. Second MixIn one was solved by creating a dummy method call_mixin(self): pass and injecting it between calls and defining self.call_mixin(). Again inelegant and will break on multiple MixIns.. Any ideas?

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  • Filtering out specific objects from a search query in Alfresco using Java

    - by Snowright
    I have a HashSet containing all groups I've retrieved from my database. I've been asked to filter this result by removing two specific groups. It seems trivial but I can't seem to come up with a solid solution for storing the specific groups I want to filter out. My idea is to just create an array containing references to the two groups I need to filter out. I can then filter out my search query with whatever is in the array. My concern is that in the future they may ask to filter out more groups and maybe an array may not be a good idea. //Creates the array containing groups to filter out String[] hiddenGroups = {"group1","group2"}; //retrieves all groups Set<String>allGroups = new HashSet<String>(); allGroups.addAll(authorityService.getAllAuthorities(AuthorityType.GROUP); List<String>results = new ArrayList<String>(); //filters out specified groups for (String group : allGroups) { boolean isHidden = false; for (String hiddenGroup : hiddenGroups) { if (hiddenGroup.equalsIgnorecase(group)) { isHidden = true; } } if (!isHidden){ results.add(group); } }

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  • What's the most DRY-appropriate way to execute an SQL command?

    - by Sean U
    I'm looking to figure out the best way to execute a database query using the least amount of boilerplate code. The method suggested in the SqlCommand documentation: private static void ReadOrderData(string connectionString) { string queryString = "SELECT OrderID, CustomerID FROM dbo.Orders;"; using (SqlConnection connection = new SqlConnection(connectionString)) { SqlCommand command = new SqlCommand(queryString, connection); connection.Open(); SqlDataReader reader = command.ExecuteReader(); try { while (reader.Read()) { Console.WriteLine(String.Format("{0}, {1}", reader[0], reader[1])); } } finally { reader.Close(); } } } mostly consists of code that would have to be repeated in every method that interacts with the database. I'm already in the habit of factoring out the establishment of a connection, which would yield code more like the following. (I'm also modifying it so that it returns data, in order to make the example a bit less trivial.) private SQLConnection CreateConnection() { var connection = new SqlConnection(_connectionString); connection.Open(); return connection; } private List<int> ReadOrderData() { using(var connection = CreateConnection()) using(var command = connection.CreateCommand()) { command.CommandText = "SELECT OrderID FROM dbo.Orders;"; using(var reader = command.ExecuteReader()) { var results = new List<int>(); while(reader.Read()) results.Add(reader.GetInt32(0)); return results; } } } That's an improvement, but there's still enough boilerplate to nag at me. Can this be reduced further? In particular, I'd like to do something about the first two lines of the procedure. I don't feel like the method should be in charge of creating the SqlCommand. It's a tiny piece of repetition as it is in the example, but it seems to grow if transactions are being managed manually or timeouts are being altered or anything like that.

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  • Which templating languages output HTML *as a tree of nodes*?

    - by alamar
    HTML is a tree of nodes, before all. It's not just a text. However, most templating engines handle their input and output as it was just a text; they don't care what happens around their tags, their {$foo}'s and <% bar() %>'s; also they don't care about what are they outputting. Sometimes they happen to produce a correct html, but that's just a coincidence; they didn't aim for that, all they wanted is to replace some funny marks in the text stream with their evaluation. There are a few templating engines which do treat their output as a set of nodes; XSLT and Haml come to mind. For some tasks, this has advantages: for example, you can automatically reformat (like, delete all empty text nodes; auto-indent; word-wrap). The result is guaranteed to be a correct xml/sgml unless you use a strict subset of operations that can break that. Also, such templating engine would automatically quote strings, differently in text nodes and in attributes, because it strictly knows whether you're writing an attribute or a text node. Moreover, it can conditionally remove a node from output because it knows where it does begin and end, which is useful, and do other non-trivial node operations. You might not like XSLT for its verbosiness or functionalness, but it's damn helps that your template is xmllint-able XML, and your output is a good sgml/xml. So the question is: Which template engines do you know that treat their output as a set of correct nodes, not just an unstructured text? I know XSLT, Haml and some obscure python-based one. Moar!

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  • MSMQ - Message Queue Abstraction and Pattern

    - by Maxim Gershkovich
    Hi All, Let me define the problem first and why a messagequeue has been chosen. I have a datalayer that will be transactional and EXTREMELY insert heavy and rather then attempt to deal with these issues when they occur I am hoping to implement my application from the ground up with this in mind. I have decided to tackle this problem by using the Microsoft Message Queue and perform inserts as time permits asynchronously. However I quickly ran into a problem. Certain inserts that I perform may need to be recalled (ie: retrieved) immediately (imagine this is for POS system and what happens if you need to recall the last transaction - one that still hasn’t been inserted). The way I decided to tackle this problem is by abstracting the MessageQueue and combining it in my data access layer thereby creating the illusion of a single set of data being returned to the user of the datalayer (I have considered the other issues that occur in such a scenario (ie: essentially dirty reads and such) and have concluded for my purposes I can control these issues). However this is where things get a little nasty... I’ve worked out how to get the messages back and such (trivial enough problem) but where I am stuck is; how do I create a generic (or at least somewhat generic) way of querying my message queue? One where I can minimize the duplication between the SQL queries and MessageQueue queries. I have considered using LINQ (but have very limited understanding of the technology) and have also attempted an implementation with Predicates which so far is pretty smelly. Are there any patterns for such a problem that I can utilize? Am I going about this the wrong way? Does anyone have an of their own ideas about how I can tackle this problem? Does anyone even understand what I am talking about? :-) Any and ALL input would be highly appreciated and seriously considered… Thanks again.

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  • What is the minimal licensable source code?

    - by Hernán Eche
    Let's suppose I want to "protect" this code about being used without attribution, patenting it, or through any open source licence... #include<stdio.h> int main (void) { int version=2; printf("\r\n.Hello world, ver:(%d).", version); return 0; } It's a little obvious or just a language definition example.. When a source stop being "trivial, banal, commonplace, obvious", and start to be something that you may claim "rights"? Perhaps it depends on who read it, something that could be great geniality for someone that have never programmed, could be just obvious for an expert. It's easy when watching two sources there are 10000 same lines of code, that's a theft.. but that's not always so obvious. How to measure amount of "ownness", it's about creativity? line numbers? complexity? I can't imagine objetive answers for that, only some patches. For example perhaps the complexity, It's not fair to replace "years of engeneering" with "copy and paste". But is there any objetive index for objetive determination of this subject? (In a funny way I imagine this criterion: If the licence is longer than the code, then there is no owner, just to punish not caring storage space and world resources =P)

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  • Protecting my apps security from deassembling

    - by sandis
    So I recently tested deassembling one of my android apps, and to my horror I discovered that the code was quite readable. Even worse, all my variable names where intact! I thought that those would be compressed to something unreadable at compile time. The app is triggered to expire after a certain time. However, now it was trivial for me to find my function named checkIfExpired() and find the variable "expired". Is there any good way of making it harder for a potential hacker messing with my app? Before someone states the obvious: Yes, it is security through obscurity. But obviously this is my only option since the user always will have access to all my code. This is the same for all apps. The details of my deactivation-thingy is unimportant, the point is that I dont want deassembler to understand some of the things I do. side questions: Why are the variable names not compressed? Could it be the case that my program would run faster if I stopped using really long variable names, as are my habit?

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  • Searching Natural Language Sentence Structure

    - by Cerin
    What's the best way to store and search a database of natural language sentence structure trees? Using OpenNLP's English Treebank Parser, I can get fairly reliable sentence structure parsings for arbitrary sentences. What I'd like to do is create a tool that can extract all the doc strings from my source code, generate these trees for all sentences in the doc strings, store these trees and their associated function name in a database, and then allow a user to search the database using natural language queries. So, given the sentence "This uploads files to a remote machine." for the function upload_files(), I'd have the tree: (TOP (S (NP (DT This)) (VP (VBZ uploads) (NP (NNS files)) (PP (TO to) (NP (DT a) (JJ remote) (NN machine)))) (. .))) If someone entered the query "How can I upload files?", equating to the tree: (TOP (SBARQ (WHADVP (WRB How)) (SQ (MD can) (NP (PRP I)) (VP (VB upload) (NP (NNS files)))) (. ?))) how would I store and query these trees in a SQL database? I've written a simple proof-of-concept script that can perform this search using a mix of regular expressions and network graph parsing, but I'm not sure how I'd implement this in a scalable way. And yes, I realize my example would be trivial to retrieve using a simple keyword search. The idea I'm trying to test is how I might take advantage of grammatical structure, so I can weed-out entries with similar keywords, but a different sentence structure. For example, with the above query, I wouldn't want to retrieve the entry associated with the sentence "Checks a remote machine to find a user that uploads files." which has similar keywords, but is obviously describing a completely different behavior.

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  • Lock-Free Data Structures in C++ Compare and Swap Routine

    - by slf
    In this paper: Lock-Free Data Structures (pdf) the following "Compare and Swap" fundamental is shown: template <class T> bool CAS(T* addr, T exp, T val) { if (*addr == exp) { *addr = val; return true; } return false; } And then says The entire procedure is atomic But how is that so? Is it not possible that some other actor could change the value of addr between the if and the assignment? In which case, assuming all code is using this CAS fundamental, it would be found the next time something "expected" it to be a certain way, and it wasn't. However, that doesn't change the fact that it could happen, in which case, is it still atomic? What about the other actor returning true, even when it's changes were overwritten by this actor? If that can't possibly happen, then why? I want to believe the author, so what am I missing here? I am thinking it must be obvious. My apologies in advance if this seems trivial.

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  • Installing Mercurial on Windows Apache XAMPP Tutorial

    - by Tim Dellas
    After asking this question (http://stackoverflow.com/questions/2675764/xampp-mercurial-installation-on-windows-apache-hgwebdir-cgi-script-error) and reading though the whole internet including this question (http://stackoverflow.com/questions/644322/how-do-i-get-mercurials-hgwebdir-working-on-windows) and all its links for about 10 hours, I seem to not be able to find a solution. I begun with this tutorial http://mercurial.selenic.com/wiki/HgWebDirStepByStep ... and I really don't want to install ancient versions of Mercurial. I got my windows-apache to run Python scripts, CGI-Scripts, publish them in the wild, but hgwebdir just won't work. Question 1: Can someone please enrich his personal blog with a tutorial on how to install MERCURIAL on a WINDOWS XAMPP installation and make it visible to the world? I guarantee a lot of pageviews, as this is not a trivial problem. And this would sincerely help a lot of other people I guess. Question 2: For example, even after browsing half a day through everywhere, I just cannot find out, which version of python I need to pair with the freshest version of mercurial, and I get the "magic number is wrong"-error. This would be my question, if noone has time to make up a nice blogpost. Sorry for being a bit frustrated.

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  • Laravel4: Call to a member function on a non-object

    - by s0hno
    The following code will throw an error Call to a member function `links()` on a non-object routes.php: Route::get('videos', function(){ $data = DB::table('video_data_r')->paginate(5); return View::make('video',$data); }); Corresponding video view: <?php foreach($data as $item): ?> <div class="video_entry"> <a href="<?php echo $item -> url; ?>" target="_blank"><img src="<?php echo $item -> thumb; ?>" /></a> <a href="<?php echo $item -> url; ?>" target="_blank"><?php echo $item -> title; ?>"</a> </div> <?php endforeach; ?> <?php echo $data->links();?> Could you give me a good hint on what looks like a trivial error?

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  • Efficiency of manually written loops vs operator overloads (C++)

    - by Sagekilla
    Hi all, in the program I'm working on I have 3-element arrays, which I use as mathematical vectors for all intents and purposes. Through the course of writing my code, I was tempted to just roll my own Vector class with simple +, -, *, /, etc overloads so I can simplify statements like: for (int i = 0; i < 3; i++) r[i] = r1[i] - r2[i]; // becomes: r = r1 - r2; Which should be more or less identical in generated code. But when it comes to more complicated things, could this really impact my performance heavily? One example that I have in my code is this: Manually written version: for (int j = 0; j < 3; j++) { p.vel[j] = p.oldVel[j] + (p.oldAcc[j] + p.acc[j]) * dt2 + (p.oldJerk[j] - p.jerk[j]) * dt12; p.pos[j] = p.oldPos[j] + (p.oldVel[j] + p.vel[j]) * dt2 + (p.oldAcc[j] - p.acc[j]) * dt12; } Using a Vector class with operator overloads: p.vel = p.oldVel + (p.oldAcc + p.acc) * dt2 + (p.oldJerk - p.jerk) * dt12; p.pos = p.oldPos + (p.oldVel + p.vel) * dt2 + (p.oldAcc - p.acc) * dt12; I am compiling my code for maximum possible speed, as it's extremely important that this code runs quickly and calculates accurately. So will me relying on my Vector's for these sorts of things really affect me? For those curious, this is part of some numerical integration code which is not trivial to run in my program. Any insight would be appreciated, as would any idioms or tricks I'm unaware of.

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  • Findbugs and comparing

    - by Rob Goodwin
    I recently started using the findbugs static analysis tool in a java build I was doing. The first report came back with loads of High Priority warnings. Being the obsessive type of person, I was ready to go knock them all out. However, I must be missing something. I get most of the warnings when comparing things. Such as the following code: public void setSpacesPerLevel(int value) { if( value >= 0) { ... produces a high priority warning at the if statement that reads. File: Indenter.java, Line: 60, Type: BIT_AND_ZZ, Priority: High, Category: CORRECTNESS Check to see if ((...) & 0) == 0 in sample.Indenter.setSpacesPerLevel(int) I am comparing an int to an int, seems like a common thing. I get quite a few of that type of error with similar simple comparisons. I have alot of other high priority warnings on what appears to be simple code blocks. Am I missing something here? I realize that static analysis can produce false positives, but the errors I am seeing seem too trivial of a case to be a false positive. This one has me scratching my head as well. for(int spaces = 0;spaces < spacesPerLevel;spaces++){... Which gives the following findbugs warning: File: Indenter.java, Line: 160, Type: IL_INFINITE_LOOP, Priority: High, Category: CORRECTNESS There is an apparent infinite loop in sample.Indenter.indent() This loop doesn't seem to have a way to terminate (other than by perhaps throwing an exception). Any ideas? So basically I have a handful of files and 50-60 high priority warnings similar to the ones above. I am using findbugs 1.3.9 and calling it from the findbugs ant task

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  • Are there good reasons not to use an ORM?

    - by hangy
    During my apprenticeship, I have used NHibernate for some smaller projects which I mostly coded and designed on my own. Now, before starting some bigger project, the discussion arose how to design data access and whether or not to use an ORM layer. As I am still in my apprenticeship and still consider myself a beginner in enterprise programming, I did not really try to push in my opinion, which is that using an object relational mapper to the database can ease development quite a lot. The other coders in the development team are much more experienced than me, so I think I will just do what they say. :-) However, I do not completely understand two of the main reasons for not using NHibernate or a similar project: One can just build one’s own data access objects with SQL queries and copy those queries out of Microsoft SQL Server Management Studio. Debugging an ORM can be hard. So, of course I could just build my data access layer with a lot of SELECTs etc, but here I miss the advantage of automatic joins, lazy-loading proxy classes and a lower maintenance effort if a table gets a new column or a column gets renamed. (Updating numerous SELECT, INSERT and UPDATE queries vs. updating the mapping config and possibly refactoring the business classes and DTOs.) Also, using NHibernate you can run into unforeseen problems if you do not know the framework very well. That could be, for example, trusting the Table.hbm.xml where you set a string’s length to be automatically validated. However, I can also imagine similar bugs in a “simple” SqlConnection query based data access layer. Finally, are those arguments mentioned above really a good reason not to utilise an ORM for a non-trivial database based enterprise application? Are there probably other arguments they/I might have missed? (I should probably add that I think this is like the first “big” .NET/C# based application which will require teamwork. Good practices, which are seen as pretty normal on Stack Overflow, such as unit testing or continuous integration, are non-existing here up to now.)

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  • RewriteRule to store thousands of files in subdirectories

    - by Brandon
    I have a website that will have millions of pages in a directory. I'd like to store those files on-disk in a bunch of subdirectories based on the first characters of the page name. For example http://mysite.com/hugedir/somefile.html would be stored in /var/www/html/hugedir/s/o/m/e/f/ile.html That is fairly trivial to do with a RewriteRule like so: RewriteRule ^hugedir/(.)(.)(.)(.)(.)(.*).html /hugedir/{$1}/{$2}/{$3}/{$4}/{$5}/$6.html RewriteRule ^hugedir/(.)(.)(.)(.)(.*).html /hugedir/{$1}/{$2}/{$3}/{$4}/{$5}.html RewriteRule ^hugedir/(.)(.)(.)(.*).html /hugedir/{$1}/{$2}/{$3}/{$4}.html RewriteRule ^hugedir/(.)(.)(.*).html /hugedir/{$1}/{$2}/{$3}.html RewriteRule ^hugedir/(.)(.*).html /hugedir/{$1}/{$2}.html RewriteRule ^hugedir/(.*).html /hugedir/{$1}.html However, the file name may contain hyphens or other non-standard characters and I'd really like to avoid having a directory named with a strange character. Ideally, I'd like to have a list of 'approved' characters and either eliminate or transform the unapproved characters to an underscore. Can anybody think of a way to do that? Or something else equivalent? Part of the requirement is that these be physical files on disk and it not be parsed with a scripting language.

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  • PHP IDE with Integrated Web Server

    - by seth
    Note: This is not another "What is the best PHP IDE?" question. I'm looking for a PHP IDE with a specific feature, namely an integrated / embedded (php enabled) web server; ideally with xdebug pre-bundled. I already know that Aptana 1.5 has this functionality (and some older versions of Zend Studio as well), but Aptana 1.5 hasn't been supported for quite some time and as we make the transition to PHP 5.3 and beyond, it's usefulness will diminish significantly. I've looked at some options including Eclipse PDT and NetBeans, but it seems every PHP IDE relies on a separate local/remote web server to actually interpret the code. I know installing a web server locally is fairly trivial, but this is for a classroom solution, where installing, configuring, and maintaining a web server on 1000 machines is simply not feasible. A remote server solution will also not work due to the need to use debugging functionality (xdebug currently requires a hardcoded IP for the debug client). This seems like such an obvious feature/plugin for a PHP IDE, but my research thus far has turned up no results.

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  • In what order should the Python concepts be explained to absolute beginners?

    - by Tomaž Pisanski
    I am teaching Python to undergraduate math majors. I am interested in the optimal order in which students should be introduced to various Python concepts. In my view, at each stage the students should be able to solve a non-trivial programming problem using only the tools available at that time. Each new tool should enable a simpler solution to a familiar problem. A selection of numerous concepts available in Python is essential in order to keep students focused. They should also motivated and should appreciate each newly mastered tool without too much memorization. Here are some specific questions: For instance, my predecessor introduced lists before strings. I think the opposite is a better solution. Should function definitions be introduced at the very beginning or after mastering basic structured programming ideas, such as decisions (if) and loops (while)? Should sets be introduced before dictionaries? Is it better to introduce reading and writing files early in the course or should one use input and print for most of the course? Any suggestions with explanations are most welcome.

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  • Rails: Can't set or update tag_list using a text field with acts_as_taggable_on

    - by Josh
    Hey everyone, I'm trying to add tagging to a rails photo gallery system I'm working on. It works from the back-end, but if I try to set or change it in the form view, it doesn't work. I added acts_as_taggable to the photo model and did the migrations. My gallery builder is programmed to add one tag automatically to each photo it creates. This works fine, just as if it were setting it for the console. However, I can't seem to set tags using a text_field in the photo form. Here's the code I added to my photo form: <p> <%= f.label :tag_list %><br /> <%= f.text_field :tag_list %> </p> Now, that's pretty trivial, and since :tag_list supports single-string comma-separated assignment (e.g. tag_list = "this, that, the other" #= ['this', 'that', 'the other']), I don't see why using a text field doesn't work. And to make even less sense, if a tag list has already been populated, the list will still show up in the text field when editing the photo. I just can't seem to commit any changes to the list. The documentation on their github page doesn't appear to give any information on how to set these values from the view. Any ideas? Oh, and I'm using the Rails 3 gem version.

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  • In mysql, is "explain ..." always safe?

    - by tye
    If I allow a group of users to submit "explain $whatever" to mysql (via Perl's DBI using DBD::mysql), is there anything that a user could put into $whatever that would make any database changes, leak non-trivial information, or even cause significant database load? If so, how? I know that via "explain $whatever" one can figure out what tables / columns exist (you have to guess names, though) and roughly how many records are in a table or how many records have a particular value for an indexed field. I don't expect one to be able to get any information about the contents of unindexed fields. DBD::mysql should not allow multiple statements so I don't expect it to be possible to run any query (just explain one query). Even subqueries should not be executed, just explained. But I'm not a mysql expert and there are surely features of mysql that I'm not even aware of. In trying to come up with a query plan, might the optimizer actual execute an expression in order to come up with the value that an indexed field is going to be compared against? explain select * from atable where class = somefunction(...) where atable.class is indexed and not unique and class='unused' would find no records but class='common' would find a million records. Might 'explain' evaluate somefunction(...)? And then could somefunction(...) be written such that it modifies data?

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  • Simple matrix example using C++ template class

    - by skyeagle
    I am trying to write a trivial Matrix class, using C++ templates in an attempt to brush up my C++, and also to explain something to a fellow coder. This is what I have som far: template class<T> class Matrix { public: Matrix(const unsigned int rows, const unsigned int cols); Matrix(const Matrix& m); Matrix& operator=(const Matrix& m); ~Matrix(); unsigned int getNumRows() const; unsigned int getNumCols() const; template <class T> T getCellValue(unsigned int row, unsigned col) const; template <class T> void setCellValue(unsigned int row, unsigned col, T value) const; private: // Note: intentionally NOT using smart pointers here ... T * m_values; }; template<class T> inline T Matrix::getCellValue(unsigned int row, unsigned col) const { } template<class T> inline void Matrix::setCellValue(unsigned int row, unsigned col, T value) { } I'm stuck on the ctor, since I need to allocate a new[] T, it seems like it needs to be a template method - however, I'm not sure I have come accross a templated ctor before. How can I implemnt the ctor?

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  • Is this 2D array initialization a bad idea?

    - by Brendan Long
    I have something I need a 2D array for, but for better cache performance, I'd rather have it actually be a normal array. Here's the idea I had but I don't know if it's a terrible idea: const int XWIDTH = 10, YWIDTH = 10; int main(){ int * tempInts = new int[XWIDTH * YWIDTH]; int ** ints = new int*[XWIDTH]; for(int i=0; i<XWIDTH; i++){ ints[i] = &tempInts[i*YWIDTH]; } // do things with ints delete[] ints[0]; delete[] ints; return 0; } So the idea is that instead of newing a bunch of arrays (and having them placed in different places in memory), I just point to an array I made all at once. The reason for the delete[] (int*) ints; is because I'm actually doing this in a class and it would save [trivial amounts of] memory to not save the original pointer. Just wondering if there's any reasons this is a horrible idea. Or if there's an easier/better way. The goal is to be able to access the array as ints[x][y] rather than ints[x*YWIDTH+y].

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