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  • Codeigniter Pagination: Run the Query Twice?

    - by Frank
    I'm using codeigniter and the pagination class. This is such a basic question, but I need to make sure I'm not missing something. In order to get the config items necessary to paginate results getting them from a MySQL database it's basically necessary to run the query twice is that right? In other words, you have to run the query to determine the total number of records before you can paginate. So I'm doing it like: Do this query to get number of results $this->db->where('something', $something); $query = $this->db->get('the_table_name'); $num_rows = $query->num_rows(); Then I'll have to do it again to get the results with the limit and offset. Something like: $this->db->where('something', $something); $this->db->limit($limit, $offset); $query = $this->db->get('the_table_name'); if($query->num_rows()){ foreach($query->result_array() as $row){ ## get the results here } } I just wonder if I'm actually doing this right in that the query always needs to be run twice? The queries I'm using are much more complex than what is shown above.

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  • Java: Efficiency of the readLine method of the BufferedReader and possible alternatives

    - by Luhar
    We are working to reduce the latency and increase the performance of a process written in Java that consumes data (xml strings) from a socket via the readLine() method of the BufferedReader class. The data is delimited by the end of line separater (\n), and each line can be of a variable length (6KBits - 32KBits). Our code looks like: Socket sock = connection; InputStream in = sock.getInputStream(); BufferedReader inputReader = new BufferedReader(new InputStreamReader(in)); ... do { String input = inputReader.readLine(); // Executor call to parse the input thread in a seperate thread }while(true) So I have a couple of questions: Will the inputReader.readLine() method return as soon as it hits the \n character or will it wait till the buffer is full? Is there a faster of picking up data from the socket than using a BufferedReader? What happens when the size of the input string is smaller than the size of the Socket's receive buffer? What happens when the size of the input string is bigger than the size of the Socket's receive buffer? I am getting to grips (slowly) with Java's IO libraries, so any pointers are much appreciated. Thank you!

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  • Wpf binding with nested properties

    - by byte
    ViewModel I have a property of type Member called KeyMember. The 'Member' type has an ObservableCollection called Addresses. The Address is composed of two strings - street and postcode . View I have a ListBox whose item source need to be set to ViewModels's KeyMember property and it should display the Street of all the Past Addresses in the collection. Question My ViewModel and View relationship is established properly. I am able to write a data template for the above simple case as below <ListBox ItemsSource="{Binding KeyMember.Addresses}"> <ListBox.ItemTemplate> <DataTemplate DataType="Address"> <TextBlock Text="{Binding Street}"/> </DataTemplate> </ListBox.ItemTemplate> </ListBox> How would I write the DataTemplate if I change KeyMember from type Member to ObservableCollection< Member assuming that the collection has only one element. PS: I know that for multiple elements in collection, I will have to implement the Master-Detail pattern/scenario.

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  • Is it necessary to "escape" character "<" and ">" for javascript string?

    - by Morgan Cheng
    Sometimes, server side will generate strings to be embedded in inline JavaScript code. For example, if "UserName" should be generated by ASP.NET. Then it looks like. <script> var username = "<%UserName%>"; </script> This is not safe, because a user can have his/her name to be </script><script>alert('bug')</script></script> It is XSS vulnerability. So, basically, the code should be: <script> var username = "<% JavascriptEncode(UserName)%>"; </script> What JavascriptEncode does is to add charater "\" before "/" and "'" and """. So, the output html is like. var username = "<\/scriptalert(\'bug\')<\/script<\/script"; Browser will not interpret "<\/script" as end of script block. So, XSS in avoided. However, there are still "<" and "" there. It is suggested to escape these two characters as well. First of all, I don't believe it is a good idea to change "<" to "&lt;" and "" to "&gt;" here. And, I'm not sure changing "<" to "\<" and "" to "\" is recognizable to all browsers. It seems it is not necessary to do further encoding for "<" and "". Is there any suggestion on this? Thanks.

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  • How to convert from hex-encoded string to a "human readable" string?

    - by John Jensen
    I'm using the Net-SNMP bindings for python and I'm attempting to grab an ARP cache from a Brocade switch. Here's what my code looks like: #!/usr/bin/env python import netsnmp def get_arp(): oid = netsnmp.VarList(netsnmp.Varbind('ipNetToMediaPhysAddress')) res = netsnmp.snmpwalk(oid, Version=2, DestHost='10.0.1.243', Community='public') return res arp_table = get_arp() print arp_table The SNMP code itself is working fine. Output from snmpwalk looks like this: <snip> IP-MIB::ipNetToMediaPhysAddress.128.10.200.6.158 = STRING: 0:1b:ed:a3:ec:c1 IP-MIB::ipNetToMediaPhysAddress.129.10.200.6.162 = STRING: 0:1b:ed:a4:ac:c1 IP-MIB::ipNetToMediaPhysAddress.130.10.200.6.166 = STRING: 0:1b:ed:38:24:1 IP-MIB::ipNetToMediaPhysAddress.131.10.200.6.170 = STRING: 74:8e:f8:62:84:1 </snip> But my output from the python script yields a tuple of hex-encoded strings that looks like this: ('\x00$8C\x98\xc1', '\x00\x1b\xed;_A', '\x00\x1b\xed\xb4\x8f\x81', '\x00$86\x15\x81', '\x00$8C\x98\x81', '\x00\x1b\xed\x9f\xadA', ...etc) I've spent some time googling and came across the struct module and the .decode("hex") string method, but the .decode("hex") method doesn't seem to work: Python 2.7.3 (default, Apr 10 2013, 06:20:15) [GCC 4.6.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> hexstring = '\x00$8C\x98\xc1' >>> newstring = hexstring.decode("hex") Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python2.7/encodings/hex_codec.py", line 42, in hex_decode output = binascii.a2b_hex(input) TypeError: Non-hexadecimal digit found >>> And the documentation for struct is a bit over my head.

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  • Idiomatic way to build a custom structure from XML zipper in Clojure

    - by Checkers
    Say, I'm parsing an RSS feed and want to extract a subset of information from it. (def feed (-> "http://..." clojure.zip/xml-zip clojure.xml/parse)) I can get links and titles separately: (xml-> feed :channel :item :link text) (xml-> feed :channel :item :title text) However I can't figure out the way to extract them at the same time without traversing the zipper more than once, e.g. (let [feed (-> "http://..." clojure.zip/xml-zip clojure.xml/parse)] (zipmap (xml-> feed :channel :item :link text) (xml-> feed :channel :item :title text))) ...or a variation of thereof, involving mapping multiple sequences to a function that incrementally builds a map with, say, assoc. Not only I have to traverse the sequence multiple times, the sequences also have separate states, so elements must be "aligned", so to speak. That is, in a more complex case than RSS, a sub-element may be missing in particular element, making one of sequences shorter by one (there are no gaps). So the result may actually be incorrect. Is there a better way or is it, in fact, the way you do it in Clojure?

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  • Using java.util.regex in Android apps - are there issues with this?

    - by johnrock
    In an Android app I have a utility class that I use to parse strings for 2 regEx's. I compile the 2 patterns in a static initializer so they only get compiled once, then activities can use the parsing methods statically. This works fine except that the first time the class is accessed and loaded, and the static initializer compiles the pattern, the UI hangs for close to a MINUTE while it compiles the pattern! After the first time, it flies on all subsequent calls to parseString(). My regEx that I am using is rather large - 847 characters, but in a normal java webapp this is lightning fast. I am testing this so far only in the emulator with a 1.5 AVD. Could this just be an emulator issue or is there some other reason that this pattern is taking so long to compile? private static final String exp1 = "(insertratherlong---847character--regexhere)"; private static Pattern regex1 = null; private static final String newLineAndTagsExp = "[<>\\s]"; private static Pattern regexNewLineAndTags = null; static { regex1 = Pattern.compile(exp1, Pattern.CASE_INSENSITIVE); regexNewLineAndTags = Pattern.compile(newLineAndTagsExp); } public static String parseString(CharSequence inputStr) { String replacementStr = "replaceMentText"; String resultString = "none"; try { Matcher regexMatcher = regex1.matcher(inputStr); try { resultString = regexMatcher.replaceAll(replacementStr); } catch (IllegalArgumentException ex) { } catch (IndexOutOfBoundsException ex) { } } catch (PatternSyntaxException ex) { } return resultString; }

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  • How would the 'Model' in a Rails-type webapp be implemented in a functional programming langauge?

    - by ceptorial
    In MVC web development frameworks such as Ruby on Rails, Django, and CakePHP, HTTP requests are routed to controllers, which fetch objects which are usually persisted to a backend database store. These objects represent things like users, blog posts, etc., and often contain logic within their methods for permissions, fetching and/or mutating other objects, validation, etc. These frameworks are all very much object oriented. I've been reading up recently on functional programming and it seems to tout tremendous benefits such as testability, conciseness, modularity, etc. However most of the examples I've seen for functional programming implement trivial functionality like quicksort or the fibonnacci sequence, not complex webapps. I've looked at a few 'functional' web frameworks, and they all seem to implement the view and controller just fine, but largely skip over the whole 'model' and 'persistence' part. (I'm talking more about frameworks like Compojure which are supposed to be purely functional, versus something Lift which conveniently seems to use the OO part of Scala for the model -- but correct me if I'm wrong here.) I haven't seen a good explanation of how functional programming can be used to provide the metaphor that OO programming provides, i.e. tables map to objects, and objects can have methods which provide powerful, encapsulated logic such as permissioning and validation. Also the whole concept of using SQL queries to persist data seems to violate the whole 'side effects' concept. Could someone provide an explanation of how the 'model' layer would be implemented in a functionally programmed web framework?

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  • How to make a WPF ComboBox editable with custom values

    - by Liam
    I would like to have a combobox that allows selection from a list of values and also allow a custom value from the typed in text. For display reasons the items are a complex type (lets say the combobox item template displays a patch of color and a flag indicating if it is a custom color). public class ColorLevel { public decimal Intensity { get; set; } public bool IsCustom { get; set; } public Color BaseColor { get; set; } public override ToString() { return string.Format("{0}", Intensity*100); } } Example items var items = new [] { new ColorLevel { Intensity = 0.9m, IsCustom = false, BaseColor = Color.Red }, new ColorLevel { Intensity = 0.7m, IsCustom = false, BaseColor = Color.Red } } XAML <ComboBox SelectedItem="{Binding Path=SelectedColorLevel}" IsEditable="true" IsTextSearchEnabled="true"> </ComboBox> So the above markup works when an item is selected from the item list. And as you type with the text search the matching items are selected. If the typed text doesn't match an item then the SelectedColorLevel is set to null. The question is at what point (and how) is it best to create a new custom item that can be set to the SelectedColorLevel when the typed text doesn't match an item. For example I would want to assign a new item to the selected value such as new ColorLevel { Intensity = decimal.Parse(textvalue), IsCustom = true } or using an appropriate converter and databinding to the Text property.

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  • how to find the last instance of a setting in a config file

    - by Glenn Kelley
    I am trying to figure out how to find the last entry of a string in multiple config files across a server. Each of the strings will be in the /home/***usernamewouldbehere/public_html/typo3conf/localconf.php file In short - the last entry in the config files will point to the database server the application is utilizing - and we need to know which accounts point to which db server. While I can run something like this - grep "$_db_host" /home/*/public_html/conf/localconf.php It does not really help much because it gives us way to much information ... and not what we really need. What i really need to know is the last entry of this string $_db_host = 'xx'; and to sort them out in an export file Since the config files may have multiple entries (example below) $_db_host = 'localhost'; $_db_host = '10.0.1.234'; It would be great to list in a file all of those that have the entry for 'localhost' and then list all of those that have the entry for '10.0.1.234' (or whichever server there may be there) but even if I need to do that manually that would be great. I am not sure how to get to it using Awk - ... and really stuck What I am hoping for is something that would be piped as follows db_host = localhost /home/username1/www/conf/localconf.php db_host = localhost / home/username2/public_html/conf/localconf.php db_host= '10.1.2.23' /home/username55/public_html/conf/localconf.php hoping that helps you help me :-)

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  • Testing Finite State Machines

    - by Pondidum
    I have inherited a large and firaly complex state machine at work. It has 31 possbile states to be in. It has the following inputs: Enum: Current State (so 0 - 30) Enum: source (currently only 2 entries) Boolean: Request Boolean: type Enum: Status (3 states) Enum: Handling (3 states) Boolean: Completed The 31 States are really needed (big business process). Breaking into seperate state machines doesnt seem feasable - each state is distinct. I have written tests for one set of inputs (the most common set), with one test per input (all inputs constant, except for the State input): [Subject("Application Process States")] public class When_state_is_meeting2Requested : AppProcessBase { Establish context = () => { //Setup.... }; Because of = () => process.Load(jas, vac); It Current_node_should_be_meeting2Requested = () => process.CurrentNode.ShouldBeOfType<meetingRequestedNode>(); It Can_move_to_clientDeclined = () => Check(process, process.clientDeclined); It Can_move_to_meeting1Arranged = () => Check(process, process.meeting1Arranged); It Can_move_to_meeting2Arranged = () => Check(process, process.meeting2Arranged); It Can_move_to_Reject = () => Check(process, process.Reject); It Cannot_move_to_any_other_state = () => AllOthersFalse(process); } As no one is entirely sure on what the output should be for each state and set of inputs i have been starting to write tests for it, however on calculation i will need to write 4320 ( 30*2*2*2*3*3*2 ) tests for it. Does anyone have any suggestions on how i should go about testing this?

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  • How to provide js-ctypes in a spidermonkey embedding?

    - by Triston J. Taylor
    Summary I have looked over the code the SpiderMonkey 'shell' application uses to create the ctypes JavaScript object, but I'm a less-than novice C programmer. Due to the varying levels of insanity emitted by modern build systems, I can't seem to track down the code or command that actually links a program with the desired functionality. method.madness This js-ctypes implementation by The Mozilla Devs is an awesome addition. Since its conception, scripting has been primarily used to exert control over more rigorous and robust applications. The advent of js-ctypes to the SpiderMonkey project, enables JavaScript to stand up and be counted as a full fledged object oriented rapid application development language flying high above 'the bar' set by various venerable application development languages such as Microsoft's VB6. Shall we begin? I built SpiderMonkey with this config: ./configure --enable-ctypes --with-system-nspr followed by successful execution of: make && make install The js shell works fine and a global ctypes javascript object was verified operational in that shell. Working with code taken from the first source listing at How to embed the JavaScript Engine -MDN, I made an attempt to instantiate the JavaScript ctypes object by inserting the following code at line 66: /* Populate the global object with the ctypes object. */ if (!JS_InitCTypesClass(cx, global)) return NULL; /* I compiled with: g++ $(./js-config --cflags --libs) hello.cpp -o hello It compiles with a few warnings: hello.cpp: In function ‘int main(int, const char**)’: hello.cpp:69:16: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] hello.cpp:80:20: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings] hello.cpp:89:17: warning: NULL used in arithmetic [-Wpointer-arith] But when you run the application: ./hello: symbol lookup error: ./hello: undefined symbol: JS_InitCTypesClass Moreover JS_InitCTypesClass is declared extern in 'dist/include/jsapi.h', but the function resides in 'ctypes/CTypes.cpp' which includes its own header 'CTypes.h' and is compiled at some point by some command during 'make' to yeild './CTypes.o'. As I stated earlier, I am less than a novice with the C code, and I really have no idea what to do here. Please give or give direction to a generic example of making the js-ctypes object functional in an embedding.

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  • Oracle output: cursor, file, or very long string?

    - by Klay
    First, the setup: I have a table in an Oracle10g database with spatial columns. I need to be able to pass in a spatial reference so that I can reproject the geometry into an arbitrary coordinate system. Ultimately, I need to compress the results of this projection to a zip file and make it available for download through a Silverlight project. I would really appreciate ideas as to the best way to accomplish this. In the examples below, the SRID is the Spatial reference ID integer used to convert the geometric points into a new coordinate system. In particular, I can see a couple of possibilities. There are many more, but this is an idea of how I'm thinking: a) Pass SRID to a dynamic view -- perform projection, output a cursor -- send cursor to UTL_COMPRESS -- write output to a file (somehow) -- send URL to Silverlight app b) Use SRID to call Oracle function from Silverlight app -- perform projection, output a string -- build strings into a file -- compress file using SharpZipLib library in .NET -- send bytestream back to Silverlight app I've done the first two steps of b), and the conversion of 100 points took about 7 seconds, which is unacceptably slow. I'm hoping it would be faster doing the processing totally in Oracle. If anyone can see potential problems with either way of doing this, or can suggest a better way, it would be very helpful. Thanks!

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  • Java: Implement own message queue (threadsafe)

    - by derMax
    The task is to implement my own messagequeue that is thread safe. My approach: public class MessageQueue { /** * Number of strings (messages) that can be stored in the queue. */ private int capacity; /** * The queue itself, all incoming messages are stored in here. */ private Vector<String> queue = new Vector<String>(capacity); /** * Constructor, initializes the queue. * * @param capacity The number of messages allowed in the queue. */ public MessageQueue(int capacity) { this.capacity = capacity; } /** * Adds a new message to the queue. If the queue is full, it waits until a message is released. * * @param message */ public synchronized void send(String message) { //TODO check } /** * Receives a new message and removes it from the queue. * * @return */ public synchronized String receive() { //TODO check return "0"; } } If the queue is empty and I call remove(), I want to call wait() so that another thread can use the send() method. Respectively, I have to call notifyAll() after every iteration. Question: Is that possible? I mean does it work that when I say wait() in one method of an object, that I can then execute another method of the same object? And another question: Does that seem to be clever?

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  • Java assignment issues - Is this atomic?

    - by Bob
    Hi, I've got some questions about Java's assigment. Strings I've got a class: public class Test { private String s; public synchronized void setS(String str){ s = s + " - " + str; } public String getS(){ return s; } } I'm using "synchronized" in my setter, and avoiding it in my getter, because in my app, there are a tons of data gettings, and very few settings. Settings must be synchronized to avoid inconsistency. My question is: is getting and setting a variable atomic? I mean, in a multithreaded environment, Thread1 is about to set variable s, while Thread2 is about to get "s". Is there any way the getter method could get something different than the s's old value or the s's new value (suppose we've got only two threads)? In my app it is not a problem to get the new value, and it is not a problem to get the old one. But could I get something else? What about HashMap's getting and putting? considering this: public class Test { private Map<Integer, String> map = Collections.synchronizedMap(new HashMap<Integer, String>()); public synchronized void setMapElement(Integer key, String value){ map.put(key, value); } public String getValue(Integer key){ return map.get(key); } } Is putting and getting atomic? How does HashMap handle putting an element into it? Does it first remove the old value and put the now one? Could I get other than the old value or the new value? Thanks in advance!

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  • How to represent and insert into an ordered list in SQL?

    - by Travis
    I want to represent the list "hi", "hello", "goodbye", "good day", "howdy" (with that order), in a SQL table: pk | i | val ------------ 1 | 0 | hi 0 | 2 | hello 2 | 3 | goodbye 3 | 4 | good day 5 | 6 | howdy 'pk' is the primary key column. Disregard its values. 'i' is the "index" that defines that order of the values in the 'val' column. It is only used to establish the order and the values are otherwise unimportant. The problem I'm having is with inserting values into the list while maintaining the order. For example, if I want to insert "hey" and I want it to appear between "hello" and "goodbye", then I have to shift the 'i' values of "goodbye" and "good day" (but preferably not "howdy") to make room for the new entry. So, is there a standard SQL pattern to do the shift operation, but only shift the elements that are necessary? (Note that a simple "UPDATE table SET i=i+1 WHERE i=3" doesn't work, because it violates the uniqueness constraint on 'i', and also it updates the "howdy" row unnecessarily.) Or, is there a better way to represent the ordered list? I suppose you could make 'i' a floating point value and choose values between, but then you have to have a separate rebalancing operation when no such value exists. Or, is there some standard algorithm for generating string values between arbitrary other strings, if I were to make 'i' a varchar? Or should I just represent it as a linked list? I was avoiding that because I'd like to also be able to do a SELECT .. ORDER BY to get all the elements in order.

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  • Starting a process in one HTTP call and getting results in another

    - by KillianDS
    Hi, I'm writing a very simple testing framework for my application, the design isn't perfect, but I don't have time to write something more complex. Essentially, I have a client and server-application, on my server I want a small python web server to start the server application with given test sequences on a GET or POST call. Also, the application prints some testdata to stderr which I'd like to catch and return in another HTTP call. At the moment I have this: from subprocess import Popen, PIPE from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer p = None class MyHandler(BaseHTTPRequestHandler): def do_GET(self): global p if self.path.endswith("start/"): p = Popen(["./bin/Release/simplex264","BBB-360","127.0.0.1"], stderr=PIPE) print 'started' return elif self.path.endswith("getResults/"): self.wfile.write(p.stderr.read()) return self.send_error(404,'File Not Found: %s' % self.path) def main(): try: server = HTTPServer(('localhost', 9876), MyHandler) print 'Started server...' server.serve_forever() except KeyboardInterrupt: print 'Shutting down...' server.socket.close() if __name__ == '__main__': main() Which 'works', except for one part, when I try to open http://localhost:9876/start/, it does not return before the process ended. However, the 'started' appears in my shell immediately (I added this because I thought the Popen call would only return after execution). I do not know the perfect inner workings of Popen and BaseHTTPRequestHandler however and do not really know where it goes wrong. Is there any way to make this work asynchronously?

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  • Is the Unicode prefix N still needed in SQL Compact Edition?

    - by Dave
    At least in previous versions of SQL Server, you had to prefix Unicode string constants with an "N" to make them be treated as Unicode. Thus, select foo from bar where fizz = N'buzz' (See "Server-Side Programming with Unicode" for SQL Server 2005 "from the horse's mouth" documentation.) We have an application that is using SQL Compact Edition and I am wondering if that is still necessary. From the testing I am doing, it appears to be unneeded. That is, the following SQL statements both behave identically in SQL CE, but the second one fails in SQL Server 2005: select foo from bar where foo=N'???' select foo from bar where foo='???' (I hope I'm not swearing in some language I don't know about...) I'm wondering if that is because all strings are treated as Unicode in SQL CE, or if perhaps the default code page is now Unicode-aware. If anyone has seen any official documentation, either yea or nay, I'd appreciate it. I know I could go the safe route and just add the "N"'s, but there's a lot of code that will need changed, and if I don't need to, I don't want to! Thanks for your help!

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  • User preferences using SQL and JavaScript

    - by Shyam
    Hi, I am using Server Side JavaScript - yes, I am actually using Server Side JavaScript. To complexify things even more, I use Oracle as a backend database (10g). With some crazy XSLT and mutant-like HTML generation, I can build really fancy web forms - yes, I am aware of Rails and other likewise frameworks and I choose the path of horror instead. I have no JQuery or other fancy framework at my disposal, just plain ol' JavaScript that should be supported by the underlying engine called Mozilla Rhino. Yes, it is insane and I love it. So, I have a bunch of tables at my disposal and some of them are filled with associative keys that link to values. As I am a people pleaser, I want to add some nifty user-preference driven solutions. My users have all an unique user_id and this user_id is available during the entire session. My initial idea is to have a user preference table, where I have "three" columns: user_id, feature and pref_string. Using a delimiter, such as : or - (haven't thought about a suitable one yet), I could like store a bunch of preferences as a list and store its elements inside an array using the .split-method (similar like the PHP-explode function). The feature column could be like the table name or some identifier for the "feature" i want to link preferences too. I hate hardcoding objects, especially as I want to be able to back these up and reuse this functionality application-wide. Of course I would love better ideas, just keep in mind I cannot just add a library that easily. These preferences could be like "joined" to the table, so I can query it and use its values. I hope it doesn't sounds too complex, because well.. its basically something really simple I need. Thanks!

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  • Do you like Twisted?

    - by Luca
    I use Python Twisted for web development, and I don't like it? I know async programming is a great idea, I know there are may async web servers now, I know it's the only way to solve some problems you'd have with threads but I don't like. The problem is that, you're forced to program in a twisted way. So, the architecture you have in mind, very often have to be modified to fit the way twisted works. The architecture have to follow the technology, I don't think this is good. When we use callback in javascript, we don't have too many difficulties: things are usually simpler, we use a callback in response to an Ajax call. But in a server web app things are, very often, a bit more complex. Writing chain of callbacks don't seem to me a wonderful way of programming. The code is not simple, and so it is difficult to understand and to maintain. Writing twisted code we very often lost the linear intuitive idea of the algorithm we wanted to implement, especially when things grow in complexity. What's your point of view?

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  • How can we change views in a UISplitViewController other than using the popover and selecting?

    - by wolverine
    I have done a sample app with UISplitViewController studying the example they have provided. I have created three detailviews and have configured them to change by the default means. Either using the left/master view in landscape AND using the popover in the portrait orientation. Now I am trying to move to another view(previous/next) from the currentView by using left/right swipe in each view. For that, what I did was just created a function in the RootViewController. I copy-pasted the same code as that of the tablerow selection used by the popover from the RootViewController. I am calling this function from my current view's controller and is passing the respective index of the view(to be displayed next) from the current view. Function is being called but nothing is happening. Plz help me OR is anyother way to do it other than this complex step? I am giving the function that I used to change the view. - (void) rearrangeViews:(int)viewRow { UIViewController <SubstitutableDetailViewController> *detailViewController = nil; if (viewRow == 0) { DetailViewController *newDetailViewController = [[DetailViewController alloc] initWithNibName:@"DetailView" bundle:nil]; detailViewController = newDetailViewController; } if (viewRow == 1) { SecondDetailViewController *newDetailViewController = [[SecondDetailViewController alloc] initWithNibName:@"SecondDetailView" bundle:nil]; detailViewController = newDetailViewController; } if (viewRow == 2) { ThirdDetailViewController *newDetailViewController = [[ThirdDetailViewController alloc] initWithNibName:@"ThirdDetailView" bundle:nil]; detailViewController = newDetailViewController; } // Update the split view controller's view controllers array. NSArray *viewControllers = [[NSArray alloc] initWithObjects:self.navigationController, detailViewController, nil]; splitViewController.viewControllers = viewControllers; [viewControllers release]; if (rootPopoverButtonItem != nil) { [detailViewController showRootPopoverButtonItem:self.rootPopoverButtonItem]; } [detailViewController release]; }

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  • Making Javascript and HTML5 games

    - by Jeff Meatball Yang
    A long time ago (Netscape 4-era), I wrote Javascript-based games: Pong, Minesweeper, and John Conway's Life among them. I'm getting back into it, and want to get my hands even dirtier. I have a few games in mind: Axis & Allies clone, with rugged maps and complex rules. Tetris clone, possibly with real-time player-vs-player or player-vs-computer mode Breakout clone, with a couple weapons and particle velocities In all of these, I have only a few objectives: Use JavaScript and HTML 5 - it should run on Chrome, Safari, or maybe an iPad. Start small and simple, then build-up features. Learn something new about game design and implementation. So my questions are: How would you implement these games? Do you have any technology recommendations? If you've written these games, what was the hardest part? N.B. I also want to start from first-principles - if you recommend a framework/library, I would appreciate some theory or implementation details behind it. These games are different enough that I should learn something new from each one.

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  • Why is there no autorelease pool when I do performSelectorInBackground: ?

    - by Thanks
    I am calling a method that goes in a background thread: [self performSelectorInBackground:@selector(loadViewControllerWithIndex:) withObject:[NSNumber numberWithInt:viewControllerIndex]]; then, I have this method implementation that gets called by the selector: - (void) loadViewControllerWithIndex:(NSNumber *)indexNumberObj { NSAutoreleasePool *arPool = [[NSAutoreleasePool alloc] init]; NSInteger vcIndex = [indexNumberObj intValue]; Class c; UIViewController *controller = [viewControllers objectAtIndex:vcIndex]; switch (vcIndex) { case 0: c = [MyFirstViewController class]; break; case 1: c = [MySecondViewController class]; break; default: NSLog(@"unknown index for loading view controller: %d", vcIndex); // error break; } if ((NSNull *)controller == [NSNull null]) { controller = [[c alloc] initWithNib]; [viewControllers replaceObjectAtIndex:vcIndex withObject:controller]; [controller release]; } if (controller.view.superview == nil) { UIView *placeholderView = [viewControllerPlaceholderViews objectAtIndex:vcIndex]; [placeholderView addSubview:controller.view]; } [arPool release]; } Althoug I do create an autorelease pool there for that thread, I always get this error: 2009-05-30 12:03:09.910 Demo[1827:3f03] *** _NSAutoreleaseNoPool(): Object 0x523e50 of class NSCFNumber autoreleased with no pool in place - just leaking Stack: (0x95c83f0f 0x95b90442 0x28d3 0x2d42 0x95b96e0d 0x95b969b4 0x93a00155 0x93a00012) If I take away the autorelease pool, I get a whole bunch of messages like these. I also tried to create an autorelease pool around the call of the performSelectorInBackground:, but that doesn't help. I suspect the parameter, but I don't know why the compiler complains about an NSCFNumber. Am I missing something? My Instance variables are all "nonatomic". Can that be a problem? UPDATE: I may also suspect that some variable has been added to an autorelease pool of the main thread (maybe an ivar), and now it trys to release that one inside the wrong autorelease pool? If so, how could I fix that? (damn, this threading stuff is complex ;) )

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  • F# List SelectMany

    - by Tuomas Hietanen
    This is quite simple question but I didn't find an answer: Is there any Seq/List operation in F# to match the LINQ SelectMany? I know I can use System.Linq in F# if I want to. I know I can make a recursive method and use F# Computation Expressions (and make even more powerful things). But if I try to prove that F# List operations are more powerful than LINQ... .Where = List.filter .Select = List.map .Aggregate = List.fold ... In C# SelectMany usage syntax is pretty simple: var flattenedList = from i in items1 from j in items2 select ... Is there any easy direct match, List.flatten, List.bind or something like that? SelectMany has a couple of signatures, but the most complex one seems to be: IEnumerable<TResult> SelectMany<TSource, TCollection, TResult>( this IEnumerable<TSource> source, Func<TSource, IEnumerable<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> resultSelector ); In F# terms this would be: ('a -> 'b list) -> ('a -> 'b -> 'c) -> 'a list -> 'c list

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  • Is it possible to execute a function in Mongo that accepts any parameters?

    - by joshua.clayton
    I'm looking to write a function to do a custom query on a collection in Mongo. Problem is, I want to reuse that function. My thought was this (obviously contrived): var awesome = function(count) { return function() { return this.size == parseInt(count); }; } So then I could do something along the lines of: db.collection.find(awesome(5)); However, I get this error: error: { "$err" : "error on invocation of $where function: JS Error: ReferenceError: count is not defined nofile_b:1" } So, it looks like Mongo isn't honoring scope, but I'm really not sure why. Any insight would be appreciated. To go into more depth of what I'd like to do: A collection of documents has lat/lng values, and I want to find all documents within a concave or convex polygon. I have the function written but would ideally be able to reuse the function, so I want to pass in an array of points composing my polygon to the function I execute on Mongo's end. I've looked at Mongo's geospatial querying and it currently on supports circle and box queries - I need something more complex.

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