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  • lock shared data using c#

    - by menacheb
    Hi, I have a program (C#) with a list of tests to do. Also, I have two thread. one to add task into the list, and one to read and remove from it the performed tasks. I'm using the 'lock' function each time one of the threads want to access to the list. Another thing I want to do is, if the list is empty, the thread who need to read from the list will sleep. and wake up when the first thread add a task to the list. Here is the code I wrote: ... List<String> myList = new List(); Thread writeThread, readThread; writeThread = new Thread(write); writeThread.Start(); readThraed = new Thread(read); readThread.Start(); ... private void write() { while(...) { ... lock(myList) { myList.Add(...); } ... if (!readThread.IsAlive) { readThraed = new Thread(read); readThread.Start(); } ... } ... } private void read() { bool noMoreTasks = false; while (!noMoreTasks) { lock (MyList)//syncronize with the ADD func. { if (dataFromClientList.Count > 0) { String task = myList.First(); myList.Remove(task); } else { noMoreTasks = true; } } ... } readThread.Abort(); } Apparently I did it wrong, and it's not performed as expected (The readTread does't read from the list). Does anyone know what is my problem, and how to make it right? Many thanks,

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  • Consecutive Tables in Latex

    - by Tim
    Hi, I wonder how to place several tables consecutively in Latex? The page with the text right before the first table has a little space but not enough for the first table, so the first table is to be placed on the top of the next page, although I use "\begin{table}[!h]" for it. The second table does not fit into the place in the rest of the page of the first table, so I think I might use longtable for it to span the rest of the page and the top of the next page. Similarly, I use longtable for the third table. The latex code is as follows: ... % some text \begin{table}[!h] \caption{Table 1. \label{tab:1}} \begin{center} \begin{tabular}{c c} ... \end{tabular} \end{center} \end{table} \begin{center} \begin{longtable}{ c c } \caption{Table 2. \label{tab:2}}\\ ... \end{longtable} \end{center} \begin{center} \begin{longtable}{ c c } \caption{Table 3. \label{tab:3}}\\ ... \end{longtable} \end{center} ... % some text In the compiled pdf file it turns out that the order of the tables is messed up. The first table is placed behind the second and third one, and the second one spans the page with text before the tables and the next page with the third one following it. I would like to know how I can make the three tables appear consecutively in order, and there are no space left blank between them and between the text and the tables? Or if what I hope is not possible, what is the best strategy then? Thanks and regards! EDIT: Removing [!h] does not make improvement, the first table is still behind the second and the third.

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  • Why my inner class DO see a NON static variable?

    - by Roman
    Earlier I had a problem when an inner anonymous class did not see a field of the "outer" class. I needed to make a final variable to make it visible to the inner class. Now I have an opposite situation. In the "outer" class "ClientListener" I use an inner class "Thread" and the "Thread" class I have the "run" method and does see the "earPort" from the "outer" class! Why? import java.io.IOException; import java.net.*; import java.io.BufferedReader; import java.io.InputStreamReader; public class ClientsListener { private int earPort; // Constructor. public ClientsListener(int earPort) { this.earPort = earPort; } public void starListening() { Thread inputStreamsGenerator = new Thread() { public void run() { System.out.println(earPort); try { System.out.println(earPort); ServerSocket listeningSocket = new ServerSocket(earPort); Socket serverSideSocket = listeningSocket.accept(); BufferedReader in = new BufferedReader(new InputStreamReader(serverSideSocket.getInputStream())); } catch (IOException e) { System.out.println(""); } } }; inputStreamsGenerator.start(); } }

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  • Creating a function in Postgresql that does not return composite values

    - by celenius
    I'm learning how to write functions in Postgresql. I've defined a function called _tmp_myfunction() which takes in an id and returns a table (I also define a table object type called _tmp_mytable) -- create object type to be returned CREATE TYPE _tmp_mytable AS ( id integer, cost double precision ); -- create function which returns query CREATE OR REPLACE FUNCTION _tmp_myfunction( id integer ) RETURNS SETOF _tmp_mytable AS $$ BEGIN RETURN QUERY SELECT id, cost FROM sales WHERE id = sales.id; END; $$ LANGUAGE plpgsql; This works fine when I use one id and call it using the following approach: SELECT * FROM _tmp_myfunction(402); What I would like to be able to do is to call it, but to use a column of values instead of just one value. However, if I use the following approach I end up with all values of the table in one column, separated by commas: -- call function using all values in a column SELECT _tmp_myfunction(t.id) FROM transactions as t; I understand that I can get the same result if I use SELECT _tmp_myfunction(402); instead of SELECT * FROM _tmp_myfunction(402); but I don't know how to construct my query in such a way that I can separate out the results.

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  • Differences between Assembly Code output of the same program

    - by ultrajohn
    I have been trying to replicate the buffer overflow example3 from this article aleph one I'm doing this as a practice for a project in a computer security course i'm taking so please, I badly need your help. I've been the following the example, performing the tasks as I go along. My problem is the assembly code dumped by gdb in my computer (i'm doing this on a debian linux image running on VM Ware) is different from that of the example in the article. There are some constructs which I find confusing. Here is the one from my computer: here is the one from the article... Dump of assembler code for function main: 0x8000490 <main>: pushl %ebp 0x8000491 <main+1>: movl %esp,%ebp 0x8000493 <main+3>: subl $0x4,%esp 0x8000496 <main+6>: movl $0x0,0xfffffffc(%ebp) 0x800049d <main+13>: pushl $0x3 0x800049f <main+15>: pushl $0x2 0x80004a1 <main+17>: pushl $0x1 0x80004a3 <main+19>: call 0x8000470 <function> 0x80004a8 <main+24>: addl $0xc,%esp 0x80004ab <main+27>: movl $0x1,0xfffffffc(%ebp) 0x80004b2 <main+34>: movl 0xfffffffc(%ebp),%eax 0x80004b5 <main+37>: pushl %eax 0x80004b6 <main+38>: pushl $0x80004f8 0x80004bb <main+43>: call 0x8000378 <printf> 0x80004c0 <main+48>: addl $0x8,%esp 0x80004c3 <main+51>: movl %ebp,%esp 0x80004c5 <main+53>: popl %ebp 0x80004c6 <main+54>: ret 0x80004c7 <main+55>: nop As you can see, there are differences between the two. I'm confuse and I can't understand totally the assembly code from my computer. I would like to know the differences between the two. How is pushl different from push, mov vs movl , and so on... what does the expression 0xhexavalue(%register) means? I am sorry If I'm asking a lot, But I badly need your help. Thanks for the help really...

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  • Project Euler problem 214, How can i make it more efficient?

    - by Once
    I am becoming more and more addicted to the Project Euler problems. However since one week I am stuck with the #214. Here is a short version of the problem: PHI() is Euler's totient function, i.e. for any given integer n, PHI(n)=numbers of k<=n for which gcd(k,n)=1. We can iterate PHI() to create a chain. For example starting from 18: PHI(18)=6 = PHI(6)=2 = PHI(2)=1. So starting from 18 we get a chain of length 4 (18,6,2,1) The problem is to calculate the sum of all primes less than 40e6 which generate a chain of length 25. I built a function that calculates the chain length of any number and I tested it for small values: it works well and fast. sum of all primes<=20 which generate a chain of length 4: 12 sum of all primes<=1000 which generate a chain of length 10: 39383 Unfortunately my algorithm doesn't scale well. When I apply it to the problem, it takes several hours to calculate... so I stop it because the Project Euler problems must be solved in less than one minute. I thought that my prime detection function might be slow so I fed the program with a list of primes <40e6 to avoid the primality test... The code runs now a little bit faster, but there is still no way to get a solution in less than a few hours (and I don't want this). So is there any "magic trick" that I am missing here ? I really don't understand how to be more efficient on this one... I am not asking for the solution, because fighting with optimization is all the fun of Project Euler. However, any small hint that could put me on the right track would be welcome. Thanks !

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  • ISO/IEC Website and Charging for C and C++ Standards

    - by Michael Aaron Safyan
    The ISO C Standard (ISO/IEC 9899) and the ISO C++ Standard (ISO/IEC 14882) are not published online; instead, one must purchase the PDF for each of those standards. I am wondering what the rationale is behind this... is it not detrimental to both the C and C++ programming languages that the authoritative specification for these languages is not made freely available and searchable online? Doesn't this encourage the use of possibly inaccurate, non-authoritative sources for information regarding these standards? While I understand that much time and effort has gone into developing the C and C++ standards, I am still somewhat puzzled by the choice to charge for the specification. The OpenGroup Base Specification, for example, is available for free online; they make money buy charging for certification. Does anyone know why the ISO standards committees don't make their revenue in certifying standards compliance, instead of charging for these documents? Also, does anyone know if the ISO standards committee's atrociously looking website is intentionally made to look that way? It's as if they don't want people visiting and buying the spec. One last thing... the C and C++ standards are generally described as "open standards"... while I realize that this means that anyone is permitted to implement the standard, should that definition of "open" be revised? Charging for the standard rather than making it openly available seems contrary to the spirit of openness. P.S. I do have a copy of the ISO/IEC 9899:1999 and ISO/IEC 14882:2003, so please no remarks about being cheap or anything... although if you are tempted to say such things, you might want to consider the high school, undergraduate, and graduate students who might not have all that much extra cash. Also, you might want to consider the fact that the ISO website is really sketchy and they don't even tell you the cost until you proceed to the checkout... doesn't really encourage one to go and get a copy, now does it?

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  • how to get access to private members of nested class?

    - by macias
    Background: I have enclosed (parent) class E with nested class N with several instances of N in E. In the enclosed (parent) class I am doing some calculations and I am setting the values for each instance of nested class. Something like this: n1.field1 = ...; n1.field2 = ...; n1.field3 = ...; n2.field1 = ...; ... It is one big eval method (in parent class). My intention is -- since all calculations are in parent class (they cannot be done per nested instance because it would make code more complicated) -- make the setters only available to parent class and getters public. And now there is a problem: when I make the setters private, parent class cannot acces them when I make them public, everybody can change the values and C# does not have friend concept I cannot pass values in constructor because lazy evaluation mechanism is used (so the instances have to be created when referencing them -- I create all objects and the calculation is triggered on demand) I am stuck -- how to do this (limit access up to parent class, no more, no less)? I suspect I'll get answer-question first -- "but why you don't split the evaluation per each field" -- so I answer this by example: how do you calculate min and max value of a collection? In a fast way? The answer is -- in one pass. This is why I have one eval function which does calculations and sets all fields at once.

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  • How to choose light version of database system

    - by adopilot
    I am starting one POS (Point of sale) project. Targeting system is going to be written in C# .NET 2 WinForms and as main database server We are going to use MS-SQL Server. As we have a lot of POS devices in chain for one store I will love to have backend local data base system on each POS device. Scenario are following: When main server goes down!! POS application should continue working "off-line" with local database, until connection to main server come up again. Now I am in dilemma which local database is going to be most adoptable for me. Here is some notes for helping me point me in right direction: To be Light "My POS devices art usually old and suffering with performances" To be Free "I have a lot of devices and I do not wont additional cost beside main SQL serer" One day Ill love to try all that port on Mono and Linux OS. Here is what I've researched so far: Simple XML "Light but I am afraid of performance, My main table of items is average of 10K records" SQL-Express "I am afraid that my POS devices is poor with hardware for SQLExpress, and also hard to install on each device and configure" Less known Advantage Database Server have free distribution of offline ADT system. DBF with extended Library,"Respect for good old DBFs but that era is behind Me with clipper and DBFs" MS Access Sqlite "Mostly like for now, but I am afraid how it is going to pair with MS SQL do they have same Data types". I know that in this SO is a lot of subjective data, but at least can someone recommended some others lite database system, or things that I shod most take attention before I choice database.

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  • Zend_Date and Zend Locale; can't get it to work ><

    - by Rick de Graaf
    Loving Zend Framework, hating Zend_Date... I'm buidling an app where one of the functions is to track the time one spends on a certain task. This works great. My previous question was my incapability to get the sum of all the timestamps (time spent on each task). Well that works as a charm, but when I echo this value, it adds one hour. Using gmdate() (just for checking) and the value turns out exactly as it's supposed to. I thought to solve this problem easeliy with Zend_Local, but I can't get the damn thing to work! This is my bootstrap code: protected function _initLocale() { $locale = new Zend_Locale('nl_NL'); $locale->setLocale($locale); Zend_Registry::set('Zend_Locale', $locale); } This is the code in my view file: $date = new Zend_Date($this->timequery, null, $locale); echo $date->toString(Zend_Date::HOUR.':'.Zend_Date::MINUTE.':'.Zend_Date::SECOND); The timestamp I'm processing is: 2632 which equals 00:43:52. The output I get is: 01:43:52 I know the extra hour comes from the time difference, but I can seem to solve this with Zend_Local and Zend_Date.

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  • Clustered index - multi-part vs single-part index and effects of inserts/deletes

    - by Anssssss
    This question is about what happens with the reorganizing of data in a clustered index when an insert is done. I assume that it should be more expensive to do inserts on a table which has a clustered index than one that does not because reorganizing the data in a clustered index involves changing the physical layout of the data on the disk. I'm not sure how to phrase my question except through an example I came across at work. Assume there is a table (Junk) and there are two queries that are done on the table, the first query searches by Name and the second query searches by Name and Something. As I'm working on the database I discovered that the table has been created with two indexes, one to support each query, like so: --drop table Junk1 CREATE TABLE Junk1 ( Name char(5), Something char(5), WhoCares int ) CREATE CLUSTERED INDEX IX_Name ON Junk1 ( Name ) CREATE NONCLUSTERED INDEX IX_Name_Something ON Junk1 ( Name, Something ) Now when I looked at the two indexes, it seems that IX_Name is redundant since IX_Name_Something can be used by any query that desires to search by Name. So I would eliminate IX_Name and make IX_Name_Something the clustered index instead: --drop table Junk2 CREATE TABLE Junk2 ( Name char(5), Something char(5), WhoCares int ) CREATE CLUSTERED INDEX IX_Name_Something ON Junk2 ( Name, Something ) Someone suggested that the first indexing scheme should be kept since it would result in more efficient inserts/deletes (assume that there is no need to worry about updates for Name and Something). Would that make sense? I think the second indexing method would be better since it means one less index needs to be maintained. I would appreciate any insight into this specific example or directing me to more info on maintenance of clustered indexes.

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  • How can I optimize retrieving lowest edit distance from a large table in SQL?

    - by Matt
    Hey, I'm having troubles optimizing this Levenshtein Distance calculation I'm doing. I need to do the following: Get the record with the minimum distance for the source string as well as a trimmed version of the source string Pick the record with the minimum distance If the min distances are equal (original vs trimmed), choose the trimmed one with the lowest distance If there are still multiple records that fall under the above two categories, pick the one with the highest frequency Here's my working version: DECLARE @Results TABLE ( ID int, [Name] nvarchar(200), Distance int, Frequency int, Trimmed bit ) INSERT INTO @Results SELECT ID, [Name], (dbo.Levenshtein(@Source, [Name])) As Distance, Frequency, 'False' As Trimmed FROM MyTable INSERT INTO @Results SELECT ID, [Name], (dbo.Levenshtein(@SourceTrimmed, [Name])) As Distance, Frequency, 'True' As Trimmed FROM MyTable SET @ResultID = (SELECT TOP 1 ID FROM @Results ORDER BY Distance, Trimmed, Frequency) SET @Result = (SELECT TOP 1 [Name] FROM @Results ORDER BY Distance, Trimmed, Frequency) SET @ResultDist = (SELECT TOP 1 Distance FROM @Results ORDER BY Distance, Trimmed, Frequency) SET @ResultTrimmed = (SELECT TOP 1 Trimmed FROM @Results ORDER BY Distance, Trimmed, Frequency) I believe what I need to do here is to.. Not dumb the results to a temporary table Do only 1 select from `MyTable` Setting the results right in the select from the initial select statement. (Since select will set variables and you can set multiple variables in one select statement) I know there has to be a good implementation to this but I can't figure it out... this is as far as I got: SELECT top 1 @ResultID = ID, @Result = [Name], (dbo.Levenshtein(@Source, [Name])) As distOrig, (dbo.Levenshtein(@SourceTrimmed, [Name])) As distTrimmed, Frequency FROM MyTable WHERE /* ... yeah I'm lost */ ORDER BY distOrig, distTrimmed, Frequency Any ideas?

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  • C# : Forcing a clean run in a long running SQL reader loop?

    - by Wardy
    I have a SQL data reader that reads 2 columns from a sql db table. once it has done its bit it then starts again selecting another 2 columns. I would pull the whole lot in one go but that presents a whole other set of challenges. My problem is that the table contains a large amount of data (some 3 million rows or so) which makes working with the entire set a bit of a problem. I'm trying to validate the field values so i'm pulling the ID column then one of the other cols and running each value in the column through a validation pipeline where the results are stored in another database. My problem is that when the reader hits the end of handlin one column I need to force it to immediately clean up every little block of ram used as this process uses about 700MB and it has about 200 columns to go through. Without a full Garbage Collect I will definately run out of ram. Anyone got any ideas how I can do this? I'm using lots of small reusable objects, my thought was that I could just call GC.Collect() on the end of each read cycle and that would flush everything out, unfortunately that isn't happening for some reason.

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  • ADO.NET Multiple simultaneous reads from an open database.

    - by Deverill
    Answer not needed - my logic was wrong and this question is invalid. Charles helped me see where I went off-tracks. Thanks I have a utility that moves data from one source to another. In the process of writing the record I check to see if it exists and do an update/insert as necessary. The difficulty I have is that as I'm writing the main record info there is a 2nd table for "custom data" that I have to check to see if it exists and do an update/insert for that as well. Example: I may be loading a pencil sharpener that may or may not exist. While I'm writing it into destination it has characteristics such as style, color, etc. and each of them may or may not exist. As written I seem to need to have 2 DataReaders open, one for the sharpener and one to check for and update color. I am new to ADO.NET, but not to programming and it's more complicated than I listed but for sanity's sake I didn't put all the details. My question is: What am I missing? You can't have 2 readers open at the same time on a connection, yet I can't close the first if I'm stepping through all products. It seems inefficient to have 2 connections, readers, etc. for this. Is there a feature of ADO.NET DBs that I'm missing? How would you do it? Thanks!

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  • XSLT - Catching parameters

    - by Brian Roisentul
    The situation is I have two xslt files: one is called from my ASP.NET code, and there, the second xslt file is imported. What I'd like to accomplish is to pass a parameter to the first one so the second xslt(the one that is imported at the first xslt) can read it. My c# code looks like this: var oArgs = new XsltArgumentList(); oArgs.AddParam("fbLikeFeatureName", "", "Facebook_Like_Button"); ltlContentBody.Text = xmlUtil.TransformXML(oXmlDoc, Server.MapPath(eSpaceId + "/styles/ExploringXSLT/ExploreContentObjects.xslt"), true); And I'm catching the param at the first xslt this way: <xsl:param name="fbLikeFeatureName" /> And then, passing it to the second xslt like this(previously, I import that file): <xsl:call-template name="Articles"> <xsl:with-param name="fbLikeFeatureName"></xsl:with-param> </xsl:call-template> Finally, I'm catching the param on the second xslt file as following: <xsl:value-of select="$fbLikeButtonName"/> What Am I doing wrong? I'm kind of new at xslt.

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  • javascript innerHTML without childNodes?

    - by John Doe
    hi all im having a firefox issue where i dont see the wood for the trees using ajax i get html source from a php script this html code contains a tag and within the tbody some more tr/td's now i want to append this tbody plaincode to an existing table. but there is one more condition: the table is part of a form and thus contains checkboxe's and drop down's. if i would use table.innerHTML += content; firefox reloads the table and reset's all elements within it which isnt very userfriendly as id like to have what i have is this // content equals transport.responseText from ajax request function appendToTable(content){ var wrapper = document.createElement('table'); wrapper.innerHTML = content; wrapper.setAttribute('id', 'wrappid'); wrapper.style.display = 'none'; document.body.appendChild(wrapper); // get the parsed element - well it should be wrapper = document.getElementById('wrappid'); // the destination table table = document.getElementById('tableid'); // firebug prints a table element - seems right console.log(wrapper); // firebug prints the content ive inserted - seems right console.log(wrapper.innerHTML); var i = 0; // childNodes is iterated 2 times, both are textnode's // the second one seems to be a simple '\n' for(i=0;i<wrapper.childNodes.length;i++){ // firebug prints 'undefined' - wth!?? console.log(wrapper.childNodes[i].innerHTML); // firebug prints a textnode element - <TextNode textContent=" "> console.log(wrapper.childNodes[i]); table.appendChild(wrapper.childNodes[i]); } // WEIRD: firebug has no problems showing the 'wrappid' table and its contents in the html view - which seems there are the elements i want and not textelements } either this is so trivial that i dont see the problem OR its a corner case and i hope someone here has that much of expirience to give an advice on this - anyone can imagine why i get textnodes and not the finally parsed dom elements i expect? btw: btw i cant give a full example cause i cant write a smaller non working piece of code its one of those bugs that occure in the wild and not in my testset thx all

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  • Installer downloads wrong version of sql server compact edition

    - by MartinStettner
    I have a Visual Studio setup project which defines SQL Server 3.5 as prerequisite. I also set it up to download the required files from the source (i.e. Microsoft). My project uses Sql Server 3.5 SP1. If I create the installer on my development machine, everything works fine. When the installer is built on the build machine, it downloads the "old" 3.5 version (without SP1) which makes my application crash. (If I install SP1 on the test system manually, the application just works find...) I installed both Visual Studio 2008 SP1 and Sql Server 3.5 SP1 on the build machine. This seems to be some issue with the prerequisite packages but they look the same on the development and the build machines. Any idea what goes wrong here? EDIT Ok, I rechecked it and the package descriptions are'nt the sames. Oddly enough, the .msi file is the right one on the build machine but the old one on the development machine, so I guess if I tried to build an installer which includes the prerequisites, I'd get the wrong result on the dev machine and the right one on the build machine. Extended question: How are the prerequesite packages (under C:\Program Files\Microsoft SDKs\Windows\v6.0A\Bootstrapper\Packages\SQL Server Compact Edition) meant to be updated to SP1? Is the SQL Server CE SP1 installer responsible for this?

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  • Validating Time & Date To Be At Least A Certain Amount Of Time In The Future

    - by MJH
    I've built a reservation form for a taxi company which works fine, but I'm having an issue with users making reservations that are due too soon in the future. Since the entire form is kind of long, I first want to make sure the user is not trying to make a reservation for less than an hour ahead of time, without them having to fill out the whole form. This is what I have come up with so far, but it's just not working: <?php //Set local time zone. date_default_timezone_set('America/New_York'); //Get current date and time. $current_time = date('Y-m-d H:i:s'); //Set reservation time variable $res_datetime = $_POST['res_datetime']; //Set event time. $event_time = strtotime($res_datetime); ?> <!doctype html> <html> <head> <meta charset="utf-8"> <title>Check Date and Time</title> </head> <?php //Check to be sure reservation time is at least one hour in the future. if (($current_time - $event_time) <= (3600)) { echo "You must make a reservation at least one hour ahead of time."; } ?> <form name="datetime" action="" method="post"> <input name="res_datetime" type="datetime-local" id="res_datetime"> <input type="submit"> </form> <body> </body> </html> How can I create a validation check to make sure the date and time of the reservation is at least one hour ahead of time?

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  • What would you write in a consitution (law book) for a programmers' country?

    - by Developer Art
    After we have got our great place to talk about professional matters and sozialize online - on SO, I believe the next logical step would be to found our own country! I invite you all to participate and bring together your available resources. We will buy an island, better even a group of island so that we could establish states like .NET territories, Java land, Linux republic etc. We will build a society of programmers (girls - we need you too). To the organizational side, we're going to need some constitution or a law book. I suggest we write it together. I make it a wiki as it should be a cooperative effort. I'll open the work. Section 1. Programmers' rights. Every citizen has a right to an Internet connection 24/7. Every citizen can freely choose the field of interest Section 2. Programmers' obligations. Every citizen must embrace the changing nature of the profession and constanly educate himself Section 3. Law enforcement. Code duplication when can be avoided is punished by limiting the bandwith speed to 64Kbit for a period of one week. Using ugly hacks instead of refactoring code is punished by cutting the Internet connection for a period of one month. Usage of technologies older than 5/10 years is punished by restricting the web access to the sites last updated 5/10 years ago for a period of one month. Please feel free to modify and extend the list. We'll need to have it ready before we proceed formally with the country foundation. A purchase fund will be established shortly. Everyone is invited to participate.

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  • Handles Comparison: empty classes vs. undefined classes vs. void*

    - by Nawaz
    Microsoft's GDI+ defines many empty classes to be treated as handles internally. For example, (source GdiPlusGpStubs.h) //Approach 1 class GpGraphics {}; class GpBrush {}; class GpTexture : public GpBrush {}; class GpSolidFill : public GpBrush {}; class GpLineGradient : public GpBrush {}; class GpPathGradient : public GpBrush {}; class GpHatch : public GpBrush {}; class GpPen {}; class GpCustomLineCap {}; There are other two ways to define handles. They're, //Approach 2 class BOOK; //no need to define it! typedef BOOK *PBOOK; typedef PBOOK HBOOK; //handle to be used internally //Approach 3 typedef void* PVOID; typedef PVOID HBOOK; //handle to be used internally I just want to know the advantages and disadvantages of each of these approaches. One advantage with Microsoft's approach is that, they can define type-safe hierarchy of handles using empty classes, which (I think) is not possible with the other two approaches. What else? EDIT: One advantage with the second approach (i.e using incomplete classes) is that we can prevent clients from dereferencing the handles (that means, this approach appears to support encapsulation strongly, I suppose). The code would not even compile if one attempts to dereference handles. What else?

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  • CompositeDataBoundControl - databound values overwritten before event is fired due to DummyDataSourc

    - by Vidar Langberget
    I have a custom servercontrol that inherits from CompositeDataBoundControl. I have three templates: one header template, one footer template and one item template. The item template can contain a checkbox that I use to decide if I should delete the item. In the footer and/or header templates I have a button with a CommandName of "DeleteItem". When that button is clicked, I handle the event in OnBubbleEvent: if (cea.CommandName == "DeleteItem") { //loop through the item list and get the selected rows List<int> itemsToDelete = new List<int>(); foreach(Control c in this.Controls){ if (c is ItemData) { ItemData oid = (ItemData)c; CheckBox chkSel = (CheckBox)oid.FindControl("chkSelected"); if (chkSel.Checked) { itemsToDelete.Add(oid.Item.Id); } } } foreach (int id in itemsToDelete) { DeleteItem(id); } } } The problem is that Item is null since the CreateChildControls method already has been run as asp.net needs to recreate the control hierarchy before the event fire. It uses the DummyDataSource and a list of null objects to recreate the control hierarchy: IEnumerator e = dataSource.GetEnumerator(); if (e != null) { while (e.MoveNext()) { ItemData container = new ItemData (e.Current as OrderItem); ITemplate itemTemplate = this.ItemTemplate; if (itemTemplate == null) { itemTemplate = new DefaultItemTemplate(); } itemTemplate.InstantiateIn(container); Controls.Add(container); if (dataBinding) { container.DataBind(); } counter++; } } The problem is this line: ItemData container = new ItemData (e.Current as OrderItem); When the control hierarchy is rebuilt before the event is fired, the e.Current is null, so when I try to find out which item was marked for deletion, I get 0 since the original value has been overwritten. Any suggestions on how to fix this?

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  • Javascript function using "this = " gives "Invalid left-hand side in assignment"

    - by Brian M. Hunt
    I am trying to get a Javascript object to use the "this" assignments of another objects' constructor, as well as assume all that objects' prototype functions. Here's an example of what I'm attempting to accomplish: /* The base - contains assignments to 'this', and prototype functions */ function ObjX(a,b) { this.$a = a, $b = b; } ObjX.prototype.getB() { return this.$b; } function ObjY(a,b,c) { // here's what I'm thinking should work: this = ObjX(a, b * 12); /* and by 'work' I mean ObjY should have the following properties: * ObjY.$a == a, ObjY.$b == b * 12, * and ObjY.getB() == ObjX.prototype.getB() * ... unfortunately I get the error: * Uncaught ReferenceError: Invalid left-hand side in assignment */ this.$c = c; // just to further distinguish ObjY from ObjX. } I'd be grateful for your thoughts on how to have ObjY subsume ObjX's assignments to 'this' (i.e. not have to repeat all the this.$* = * assignments in ObjY's constructor) and have ObjY assume ObjX.prototype. My first thought is to try the following: function ObjY(a,b,c) { this.prototype = new ObjX(a,b*12); } Ideally I'd like to learn how to do this in a prototypal way (i.e. not have to use any of those 'classic' OOP substitutes like Base2). It may be noteworthy that ObjY will be anonymous (e.g. factory['ObjX'] = function(a,b,c) { this = ObjX(a,b*12); ... }) -- if I've the terminology right. Thank you.

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  • Stored Procedure: Variable passed from PHP alters second half of query string

    - by Stephanie
    Hello everyone, Basically, we have an ASP website right now that I'm converting to PHP. We're still using the MSSQL server for the DB -- it's not moving. In the ASP, now, there's an include file with a giant sql query that's being executed. This include sits on a lot of pages and this is a simple version of what happens. Pages A, B and C all use this include file to return a listing. In ASP, Page A passes through variable A to the include file - page B passes through variable B -- page C passes through variable C, and so on. The include file builds the SQL query like this: sql = "SELECT * from table_one LEFT OUTER JOIN table_two ON table_one.id = table_two.id" then adds (remember, ASP), based on the variable passed through from the parent page, Select Case sType Case "A" sql = sql & "WHERE LOWER(column_a) <> 'no' AND LTRIM(ISNULL(column_b),'') <> '' ORDER BY column_a Case "B" sql = sql & "WHERE LOWER(column_c) <> 'no' ORDER BY lastname, firstname Case "C" sql = sql & "WHERE LOWER(column_f) <> 'no' OR LOWER(column_g) <> 'no' ORDER BY column_g As you notice, every string that's added on as the second part of the sql query is different than the previous; not just one variable can be substituted out, which is what has me stumped. How do I translate this case / switch into the stored procedure, based on the varchar input that I pass to the stored procedure via PHP? This stored procedure will actually handle a query listing for about 20 pages, so it's a hefty one and this is my first major complicated one. I'm getting there, though! I'm also just more used to MySQL, too. Not that they're that different. :P Thank you very much for your help in advance. Stephanie

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  • Scriptaculous problem in IE

    - by Django Reinhardt
    Hi there. We've got this very annoying problem with Scriptaculous and Internet Explorer 7/8. We have two Effect.toggles on the same page, but only one of them is ever working (the first one). I hope it's some simple mistake in my implementation, but I can't seem to find any decent documentation. Hopefully somebody here can help. The HTML/JS looks like this: <ul> <li id="LinkA" class="icon"> <a onclick="new Effect.toggle('divA', 'slide', { duration: 0.6 }); return false;" href="#">Show List A</a> </li> </ul> <div id="divA" style="display:none"> <div> -- Things to display -- </div> </div> <ul> <li id="LinkB" class="icon"> <a onclick="new Effect.toggle('divB', 'slide', { duration: 0.6 }); return false;" href="#">Show List B</a> </li> </ul> <div id="divB" style="display:none"> <div> -- Things to display -- </div> </div> It works perfectly in Chrome and Firefox, but the second one never works in IE 7 or 8, no matter what I do. Any help would be greatly appreciated!

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  • erlang design of a card game [closed]

    - by user601836
    I would like to discuss with you a possible implementation for a card game in erlang. The only full example I found online is OpenPoker. I would like to create one myself, so here is the implementation I have in mind: A gen_server to represent a deck: when started creates a deck of cards (shuffled). And stores it in its state. provides an handle_call (draw_card) A gen_server to represent the chat room. Stores in its state the registered name of a player process (e.g. player1, player2, luke etc etc). Exports handle_cast to join the chat (executed by default when somebody joins successfully the game) and one to broadcast a chat message to all users by calling an handle_cast on the gen_server representing a player. a gen_fsm to represent a game instance. Has two states (wait_join, and turn). Exports join/1 to join the game, play_card/2 and send_msg/2. One parameter is the pid of the player process. a gen_server to represent the player. Exports only start_link/1 where the parameter is the name to use to register the process (inside the init I call join method of gen_fsm). Has different handle_calls (e.g. get_hand, draw_card) and handle_casts (e.g. play_card, deliver_msg, and send_msg) A gen_server to represent the main process. Exports (join_game/1 which calls player:start_link/1, send_msg/2 to call player's send_msg, play_card/3 to call player's play_card). What do you think of this architecture? Thanks in advance

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