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  • How to solve generic algebra using solver/library programmatically? Matlab, Mathematica, Wolfram etc?

    - by DevDevDev
    I'm trying to build an algebra trainer for students. I want to construct a representative problem, define constraints and relationships on the parameters, and then generate a bunch of Latex formatted problems from the representation. As an example: A specific question might be: If y < 0 and (x+3)(y-5) = 0, what is x? Answer (x = -3) I would like to encode this as a Latex formatted problem like. If $y<0$ and $(x+constant_1)(y+constant_2)=0$ what is the value of x? Answer = -constant_1 And plug into my problem solver constant_1 > 0, constant_1 < 60, constant_1 = INTEGER constant_2 < 0, constant_2 > -60, constant_2 = INTEGER Then it will randomly construct me pairs of (constant_1, constant_2) that I can feed into my Latex generator. Obviously this is an extremely simple example with no real "solving" but hopefully it gets the point across. Things I'm looking for ideally in priority order * Solve algebra problems * Definition of relationships relatively straight forward * Rich support for latex formatting (not just writing encoded strings) Thanks!

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  • Run-time error 459 when using WithEvents with a class that implements another

    - by Ken Keenan
    I am developing a VBA project in Word and have encountered a problem with handling events when using a class that implements another. I define an empty class, IMyInterface: Public Sub Xyz() End Sub Public Event SomeEvent() And a class, MyClass that implements the above: Implements IMyInterface Public Event SomeEvent() Public Sub Xyz() ' ... code ... RaiseEvent SomeEvent End Sub Private Sub IMyInterface_Xyz() Xyz End Sub If I create a third class, OtherClass, that declares a member variable with the type of the interface class: Private WithEvents mMy As IMyInterface and try to initialize this variable with an instance of the implementing class: Set mMy = New MyClass I get a run-time error '459': This component doesn't support this set of events. The MSDN page for this error message states: "You tried to use a WithEvents variable with a component that can't work as an event source for the specified set of events. For example, you may be sinking events of an object, then create another object that Implements the first object. Although you might think you could sink the events from the implemented object, that isn't automatically the case. Implements only implements an interface for methods and properties." The above pretty much sums up what I'm trying to do. The wording, "that isn't automatically the case", rather than "this is flat-out impossible", seems to suggest that there is some bit of manual work I need to do to get it to work, but it doesn't tell me what! Does anybody know if this is possible in VBA?

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  • What good open source programs exist for fuzzing popular image file types?

    - by JohnnySoftware
    I am looking for a free, open source, portable fuzzing tool for popular image file types that is written in either Java, Python, or Jython. Ideally, it would accept specifications for the fuzzable fields using some kind of declarative constraints. Non-procedural grammar for specifying constraints are greatly preferred. Otherwise, might as well write them all in Python or whatever. Just specifying ranges of valid values or expressions for them. Ideally, it would support some kind of generative programming to export the fuzzer into various programming languages to suit cases where more customization was required. If it supported a direct-manipulation GUI for controlling parameter values and ranges, that would be nice too. The file formats that should be supported are: GIF JPEG PNG So basically, it should be sort of a toolkit consisting of ready-to-run utility, a framework or library, and be capable of generating the fuzzed files directly as well as from programs it generates. It needs to be simple so that test images can be created quickly. It should have a batch capability for creating a series of images. Creating just one at a time would be too painful. I do not want a hacking tool, just a QA tool. Basically, I just want to address concerns that it is taking too long to get commonplace image rendering/parsing libraries stable and trustworthy.

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  • Are bad data issues that common?

    - by Water Cooler v2
    I've worked for clients that had a large number of distinct, small to mid-sized projects, each interacting with each other via properly defined interfaces to share data, but not reading and writing to the same database. Each had their own separate database, their own cache, their own file servers/system that they had dedicated access to, and so they never caused any problems. One of these clients is a mobile content vendor, so they're lucky in a way that they do not have to face the same problems that everyday business applications do. They can create all those separate compartments where their components happily live in isolation of the others. However, for many business applications, this is not possible. I've worked with a few clients, one of whose applications I am doing the production support for, where there are "bad data issues" on an hourly basis. Yeah, it's that crazy. Some data records from one of the instances (lower than production, of course) would have been run a couple of weeks ago, and caused some other user's data to get corrupted. And then, a data script will have to be written to fix this issue. And I've seen this happening so much with this client that I have to ask. I've seen this happening at a moderate rate with other clients, but this one just seems to be out of order. If you're working with business applications that share a large amount of data by reading and writing to/from the same database, are "bad data issues" that common in your environment?

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  • Need an Overview of Possibilities for multicolumn programming

    - by Sam
    Hi folks, From source1 and source2 i gather that IE9 will NOT support multi-column css3!! Since it is still the most popular browser (another thing i cannot understand), i am left but no other choice than to use Programming Power to make multi-columns work. Now, I use three divs that float to left, and which are manually filled with text. Please don't laugh i know its stupid! But I would wish to not to have to worry about the columns and just have a one piece of (un-interrupted) text which all goes into only 1 div, and then have a program smart enough to split it up into X equally wide columns. Question: before i start reinvent the wheel, what methods of programming power have you known that tackle this elegantly? Please suggest your best working multi-column layout sources so I can evaluate which option is the best (I will update the below table). Exploring all possibilities 2011 and further, to enable multi column text user experience: Language Author SourceCodeUsage WorksOnAllMajorBrowser? ================================================================================= html manual labour put text manually in separate left-floating divs "Y" // Upside: control! Downside: few changes necessitates to reflow 3 divs manually! CSS3 w3c css3.info/preview/multi-column-layout/ "N" // {-moz-column-count: 3; -webkit-column-count: 3; } Thats all! javascript a list apart will add url soon ? // php ? ? ? //

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  • Array indexOf implementation for Internet Explorer

    - by Daemon
    There are plenty of solutions on how to get the indexOf implementation into the Array prototype so that it works under Internet Explorer, however I've stumbled upon an issue that doesn't seem to be addressed anywhere I've looked so far. Using the pretty well agreed upon implementation at MDC, I have the following code that's being problematic now: // indexOf support for IE (from MDC) if (!Array.prototype.indexOf) { Array.prototype.indexOf = function(elt /*, from*/) { var len = this.length >>> 0; var from = Number(arguments[1]) || 0; from = (from < 0) ? Math.ceil(from) : Math.floor(from); if (from < 0) from += len; for (; from < len; from++) { if (from in this && this[from] === elt) return from; } return -1; }; } var i = [1,2,3,4]; for (j in i) { alert(i[j]); } I am expecting to receive 4 alerts, each one containing one of the elements of the array. In Firefox and Chrome, that's exactly what I see, however in IE8 I get an additional alert containing the indexOf function code. What can be done to avoid this?

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  • psqlODBC won't load after installing MS SQL ODBC driver on RHEL 6

    - by Kapil Vyas
    I had the PostgreSQL drivers working on my RHEL 6. But after I installed Microsoft® SQL Server® ODBC Driver 1.0 for Linux I can no longer connect to PosgreSQL data sources. I can connect to SQL Server data sources fine. When I had this same issue a week ago I uninstalled MS SQL Server ODBC driver from Linux and it fixed the issue. I had to copy the psqlodbcw.so files from another machine to replenish the files. I don't want to do the same this time. I want both drivers to work on Linux. This time around the setup files got deleted: /usr/lib64/libodbcpsqlS.so. Replenishing it did not fix the issue. I kept getting the following error in spite of the file being present with rwx permisions: [root@localhost lib64]# isql -v STUDENT dsname pwd12345 [01000][unixODBC][Driver Manager]Can't open lib '/usr/lib64/psqlodbc.so' : file not found [ISQL]ERROR: Could not SQLConnect [root@localhost lib64]# Here is a printout of the file permissions: [root@localhost lib64]# ls -al p*.so lrwxrwxrwx. 1 root root 12 Dec 7 09:15 psqlodbc.so -> psqlodbcw.so -rwxr-xr-x. 1 root root 519496 Dec 7 09:35 psqlodbcw.so and my odbcinst.ini file looks as follows: [PostgreSQL] Description=ODBC for PostgreSQL Driver=/usr/lib/psqlodbc.so Driver64=/usr/lib64/psqlodbc.so Setup=/usr/lib/libodbcpsqlS.so Setup64=/usr/lib64/libodbcpsqlS.so FileUsage=1 UsageCount=4 I also referred to this link: http://mailman.unixodbc.org/pipermail/unixodbc-support/2010-September.txt

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  • Programming an IPTV application- Client/Server

    - by Sumit Ghosh
    I am part of a team which has been given a task to deploy an IPTV solution for a company. The system has been architect-ed like this. There is Video capture card , which receives satellite signals from a satellite receiver. This video capture card is part of a windows 7 machine. The signals need to be trans coded here and passed to a streaming server which will be received by end users. The end users will be desktop users having a C#.NET application installed to view the channels. I am confused at the choice of server software as I have multiple choices - Windows Media Server, VideoLan (VLC project), or Flash Media Server, it also supports MPEG-2 HD. My main aim to be able to stream MPEG-2 channels with HD quality and encrypt the channels at the server end so that the streams can be protected. I know reversing is possible but it wont be easy as for every naive user with wireshark snooping my streams. If any of you here has ever done such an implementation please do suggest me the best technologies I should go for. Iam open to C#,C++ and other similar languages. Any help shall be deeply appreciated. edit: End Users shall be part of Internet and not necessarily a lan, reason for this question is internet doesn't support multicast like Lan, so I need some suggestions.

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  • What's a good way to make a Flex component with placeholders in it?

    - by Daniel Brockman
    I want to create a component that has a couple of "holes" that are to be filled in differently on each use. Currently, I'm doing it like this (using the Flex 4 framework in this example --- it would look almost the same for Flex 3): public var fooComponent : IVisualElement; public var barComponent : IVisualElement; override protected function createChildren() : void { super.createChildren(); fooContainer.addElement(fooComponent); barContainer.addElement(barComponent); } <Group id="fooContainer"/> <!-- ... other components ... --> <Group id="barContainer"/> This works well, but it's kind of a lot of code to write for something so simple. What I'd like is something like this: [Bindable] public var fooComponent : IVisualElement; [Bindable] public var barComponent : IVisualElement; <Placeholder content="{fooComponent}"/> <!-- ... other components ... --> <Placeholder content="{barComponent}"/> Now, I could implement the Placeholder component myself, but I can't help wondering if there isn't a better way to do this using the existing tools in the Flex framework. Theoretically, with the proper compiler support, it could even be boiled down to something like this: <Placeholder id="fooComponent"/> <!-- ... other components ... --> <Placeholder id="barComponent"/>

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  • Using SMO to call Database.ExecuteNonQuery() concurrently?

    - by JimDaniel
    I have been banging my head against the wall trying to figure out how I can run update scripts concurrently against multiple databases in a single SQL Server instance using SMO. Our environments have an ever-increasing number of databases which need updating, and iterating through one at a time is becoming a problem (too slow). From what I understand SMO does not support concurrent operations, and my tests have bore that out. There seems to be shared memory at the Server object level, for things like DataReader context, keeps throwing exceptions such as "reader is already open." I apologize for not having the exact exceptions I am getting. I will try to get them and update this post. I am no expert on SMO and just feeling my way through to be honest. Not really sure I am approaching it the right way, but it's something that has to be done, or our productivity will slow to a crawl. So how would you guys do something like this? Am I using the wrong technology with SMO? All I am wanting to do is execute sql scripts against databases in a single sql server instance in parallel. Thanks for any help you can give, Daniel

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  • Outgoing Emails (Git Patches) Blocked by Windows Live

    - by SteveStifler
    Just recently I dove into the VideoLAN open source project. This was my first time using git, and when sending in my first patch (using git send-email --to [email protected] patches), I was sent the following message from my computer's local mail in the terminal (I'm on OSX 10.6 by the way): Mail rejected by Windows Live Hotmail for policy reasons. We generally do not accept email from dynamic IP's as they are not typically used to deliver unauthenticated SMTP e-mail to an Internet mail server. http:/www.spamhaus.org maintains lists of dynamic and residential IP addresses. If you are not an email/network admin please contact your E-mail/Internet Service Provider for help. Email/network admins, please visit http://postmaster.live.com for email delivery information and support They must think I'm a spammer. I have a dynamic IP and my ISP (Charter) won't let me get a static one, so I tried editing git preferences: git config --global user.email "[email protected]" to my gmail account. However I got the exact same message again. My guess is that it has something to do with the native mail's preferences, but I have no idea how to access them or modify them. Anybody have any ideas for solving this? Thanks!

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  • Reporting Services "cannot connect to the report server database"

    - by Dano
    We have Reporting Services running, and twice in the past 6 months it has been down for 1-3 days, and suddenly it will start working again. The errors range from not being able to view the tree root in a browser, down to being able to insert parameters on a report, but crashing before the report can generate. Looking at the logs, there is 1 error and 1 warning which seem to correspond somewhat. ERROR:Event Type: Error Event Source: Report Server (SQL2K5) Event Category: Management Event ID: 107 Date: 2/13/2009 Time: 11:17:19 AM User: N/A Computer: ******** Description: Report Server (SQL2K5) cannot connect to the report server database. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp. WARNING: always comes before the previous error Event code: 3005 Event message: An unhandled exception has occurred. Event time: 2/13/2009 11:06:48 AM Event time (UTC): 2/13/2009 5:06:48 PM Event ID: 2efdff9e05b14f4fb8dda5ebf16d6772 Event sequence: 550 Event occurrence: 5 Event detail code: 0 Process information: Process ID: 5368 Process name: w3wp.exe Account name: NT AUTHORITY\NETWORK SERVICE Exception information: Exception type: ReportServerException Exception message: For more information about this error navigate to the report server on the local server machine, or enable remote errors. During the downtime we tried restarting everything from the server RS runs on, to the database it calls to fill reports with no success. When I came in monday morning it was working again. Anyone out there have any ideas on what could be causing these issues? Edit Tried both suggestions below several months ago to no avail. This issue hasn't arisen since, maybe something out of my control has changed....

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  • Advanced search engine or server for relational database [closed]

    - by Pawel
    In my current project we are storing big volume of data in relational database. One of the recent key requirements is to enrich application by adding some advanced search capabilities. In the Project, performance is one of the important factors due to very large tables (10+ milions of records) with parent-children relations (for example: multi-level parent-child relationship, where I am looking for all parents with specific children). The search engine should also be able to check these references for hits. I have found some potential engines on stack overflow, however it looks like that all of them are dedicated rather for text search than relational db and hosted on linux os: lucene Solr Sphinx As I understand some of them use documents as a source of searching, but is it possible or efficient to create programmaticaly documents based on my relational data? As I am not familiar with all of their features/capabilities can anyone please make some recommendations or propose some different solution? To summarize my requirements: framework/engine to search relational database including decendants. support for Microsoft SQL Server can be used in .NET applications preferably hosted on Windows systems Does any of mentioned above are able to solve my problem? do you know any better solution?

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  • Could I do this blind relative to absolute path conversion (for perforce depot paths) better?

    - by wonderfulthunk
    I need to "blindly" (i.e. without access to the filesystem, in this case the source control server) convert some relative paths to absolute paths. So I'm playing with dotdots and indices. For those that are curious I have a log file produced by someone else's tool that sometimes outputs relative paths, and for performance reasons I don't want to access the source control server where the paths are located to check if they're valid and more easily convert them to their absolute path equivalents. I've gone through a number of (probably foolish) iterations trying to get it to work - mostly a few variations of iterating over the array of folders and trying delete_at(index) and delete_at(index-1) but my index kept incrementing while I was deleting elements of the array out from under myself, which didn't work for cases with multiple dotdots. Any tips on improving it in general or specifically the lack of non-consecutive dotdot support would be welcome. Currently this is working with my limited examples, but I think it could be improved. It can't handle non-consecutive '..' directories, and I am probably doing a lot of wasteful (and error-prone) things that I probably don't need to do because I'm a bit of a hack. I've found a lot of examples of converting other types of relative paths using other languages, but none of them seemed to fit my situation. These are my example paths that I need to convert, from: //depot/foo/../bar/single.c //depot/foo/docs/../../other/double.c //depot/foo/usr/bin/../../../else/more/triple.c to: //depot/bar/single.c //depot/other/double.c //depot/else/more/triple.c And my script: begin paths = File.open(ARGV[0]).readlines puts(paths) new_paths = Array.new paths.each { |path| folders = path.split('/') if ( folders.include?('..') ) num_dotdots = 0 first_dotdot = folders.index('..') last_dotdot = folders.rindex('..') folders.each { |item| if ( item == '..' ) num_dotdots += 1 end } if ( first_dotdot and ( num_dotdots > 0 ) ) # this might be redundant? folders.slice!(first_dotdot - num_dotdots..last_dotdot) # dependent on consecutive dotdots only end end folders.map! { |elem| if ( elem !~ /\n/ ) elem = elem + '/' else elem = elem end } new_paths << folders.to_s } puts(new_paths) end

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  • Pass scalar/list context to called subroutine

    - by Will
    I'm trying to write a sub that takes a coderef parameter. My sub does some initialization, calls the coderef, then does some cleanup. I need to call the coderef using the same context (scalar, list, void context) that my sub was called in. The only way I can think of is something like this: sub perform { my ($self, $code) = @_; # do some initialization... my @ret; my $ret; if (not defined wantarray) { $code->(); } elsif (wantarray) { @ret = $code->(); } else { $ret = $code->(); } # do some cleanup... if (not defined wantarray) { return; } elsif (wantarray) { return @ret; } else { return $ret; } } Obviously there's a good deal of redundancy in this code. Is there any way to reduce or eliminate any of this redundancy? EDIT   I later realized that I need to run $code->() in an eval block so that the cleanup runs even if the code dies. Adding eval support, and combining the suggestions of user502515 and cjm, here's what I've come up with. sub perform { my ($self, $code) = @_; # do some initialization... my $w = wantarray; return sub { my $error = $@; # do some cleanup... die $error if $error; # propagate exception return $w ? @_ : $_[0]; }->(eval { $w ? $code->() : scalar($code->()) }); } This gets rid of the redundancy, though unfortunately now the control flow is a little harder to follow.

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  • How to bring the parent element with floated child elements to the center of the document?

    - by Starx
    I have organized a menu. Its HTML is as follows: <ul class="topmenu"> <li><a href="sample.html">Text 1</a></li> <li><a href="sample.html">Text 2</a></li> <li><a href="sample.html">Text 3</a></li> <li><a href="sample.html">Text 4</a></li> <ul> This is a horizontal menu, so I have floated the list items to left to appear them in a horizontal line. I could have used display:inline to appear them in a single line, but since IE does not support it and I don't know any other way to do so, I used float:left;. It's css is: .topmenu { list-style:none; margin:0; padding:0; } .topmenu li { float:left; } This brings the menu in a perfect horizontal line, but the entire list is floated to the left. I want to bring the .topmenu to appear in the center of the document and keep the listitem inside it floated towards the left. I found that this is achievable by defining width property of the .topmenu, but I dont want to fix its width as the list-items are dynamically generated and thus could increase and decrease. Any one know of any solution?

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  • Need help regarding lwuit

    - by rajiv
    Hi, I have project, already developed using canvas and lib used is LCDUI. It's for nokia keyboard supported devices. Now I want to incorporate same application for touch devices. I have used touch methods like pointerpressed, etc. For normal functionality that worked pretty well. But it creates problem in commands. My application is in fullscreen mode. Commands I have created using user defined menu list. Probles is that I can not directly identify that which command has been clicked. Setting coordinates for every command is not thr feasible solution for me. I come across the new lib LWUIT, but i found out that it supports only forms(Can't we use on canvas?). and integrating LCDUI and LWUIT is also not possible(please give suggestion that can we use both in same application?). Is it possible to create form under canvas itself? Any other lib support available? thank you.

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  • What's a good way to provide additional decoration/metadata for Python function parameters?

    - by Will Dean
    We're considering using Python (IronPython, but I don't think that's relevant) to provide a sort of 'macro' support for another application, which controls a piece of equipment. We'd like to write fairly simple functions in Python, which take a few arguments - these would be things like times and temperatures and positions. Different functions would take different arguments, and the main application would contain user interface (something like a property grid) which allows the users to provide values for the Python function arguments. So, for example function1 might take a time and a temperature, and function2 might take a position and a couple of times. We'd like to be able to dynamically build the user interface from the Python code. Things which are easy to do are to find a list of functions in a module, and (using inspect.getargspec) to get a list of arguments to each function. However, just a list of argument names is not really enough - ideally we'd like to be able to include some more information about each argument - for instance, it's 'type' (high-level type - time, temperature, etc, not language-level type), and perhaps a 'friendly name' or description. So, the question is, what are good 'pythonic' ways of adding this sort of information to a function. The two possibilities I have thought of are: Use a strict naming convention for arguments, and then infer stuff about them from their names (fetched using getargspec) Invent our own docstring meta-language (could be little more than CSV) and use the docstring for our metadata. Because Python seems pretty popular for building scripting into large apps, I imagine this is a solved problem with some common conventions, but I haven't been able to find them.

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  • Can a WebServiceHost be changed to avoid the use of HttpListener?

    - by sbyse
    I am looking for a way to use a WCF WebServiceHost without having to rely on the HttpListener class and it's associated permission problems (see this question for details). I'm working on a application which communicates locally with another (third-party) application via their REST API. At the moment we are using WCF as an embedded HTTP server. We create a WebServiceHost as follows: String hostPath = "http://localhost:" + portNo; WebServiceHost host = new WebServiceHost(typeof(IntegrationService), new Uri(hostPath)); // create a webhttpbinding for rest/pox and enable cookie support for session management WebHttpBinding webHttpBinding = new WebHttpBinding(); webHttpBinding.AllowCookies = true; ServiceEndpoint ep = host.AddServiceEndpoint(typeof(IIntegrationService), webHttpBinding, ""); host.Open() ChannelFactory<IIntegrationService> cf = new ChannelFactory<IIntegrationService>(webHttpBinding, hostPath); IIntegrationService channel = cf.CreateChannel(); Everything works nicely as long as our application is run as administrator. If we run our application on a machine without administrative privileges the host.Open() will throw an HttpListenerException with ErrorCode == 5 (ERROR_ACCESS_DENIED). We can get around the problem by running httpcfg.exe from the command line but this is a one-click desktop application and that's not really as long term solution for us. We could ditch WCF and write our own HTTP server but I'd like to avoid that if possible. What's the easiest way to replace HttpListener with a standard TCP socket while still using all of the remaining HTTP scaffolding that WCF provides?

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  • Titanium TableViewRow classname with custom rows

    - by pancake
    I would like to know in what way the 'className' property of a Ti.UI.TableViewRow helps when creating custom rows. For example, I populate a tableview with custom rows in the following way: function populateTableView(tableView, data) { var rows = []; var row; var title, image; var i; for (i = 0; i < data.length; i++) { title = Ti.UI.createLabel({ text : data[i].title, width : 100, height: 30, top: 5, left: 25 }); image = Ti.UI.createImage({ image : 'some_image.png', width: 30, height: 30, top: 5, left: 5 }); /* and, like, 5+ more views or whatever */ row = Ti.UI.createTableViewRow(); row.add(titleLabel); row.add(image); rows.push(row); } tableView.setData(rows); } Of course, this example of a "custom" row is easily created using the standard title and image properties of the TableViewRow, but that isn't the point. How is the allocation of new labels, image views and other child views of a table view prevented in favour of their reuse? I know in iOS this is achieved by using the method -[UITableView dequeueReusableCellWithIdentifier:] to fetch a row object from a 'reservoir' (so 'className' is 'identifier' here) that isn't currently being used for displaying data, but already has the needed child views laid out correctly in it, thus only requiring to update the data contained within (text, image data, etc). As this system is so unbelievably simple, I have a lot of trouble believing the method employed by the Titanium API does not support this. After reading through the API and searching the web, I do however suspect this is the case. The 'className' property is recommended as an easy way to make table views more efficient in Titanium, but its relation to custom table view rows is not explained in any way. If anyone could clarify this matter for me, I would be very grateful.

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  • Database schema for Product Properties

    - by Chemosh
    As so many people I'm looking for a Products /Product Properties database schema. I'm using Ruby on Rails and (Thinking) Sphinx for faceted searches. Requirements: Adding new product types and their options should not require a change to the database schema Support faceted searches using Sphinx. Solutions I've come across: (See Bill Karwin's answer) Option 1: Single Table Inheritance Not an option really. The table would contain way to many columns. Option 2: Class Table Inheritance Ruby on Rails caches the database schema on start-up which means a restart whenever a new type of product is introduced. If you have a size able product catalog this could mean hundreds of tables. Option 3: Serialized LOB Kills being able to do faceted searches without heavy application logic. Option 4: Entity-Attribute-Value For testing purposes, EAV worked fine. However it could quickly become a mess and a maintenance hell as you add more and more options (e.g. when an option increase the prices or delivery time). What option should I go with? What other solutions are out there? Is there a silver bullet (ha) I overlooked?

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  • Groovy as a substitute for Java when using BigDecimal?

    - by geejay
    I have just completed an evaluation of Java, Groovy and Scala. The factors I considered were: readability, precision The factors I would like to know: performance, ease of integration I needed a BigDecimal level of precision. Here are my results: Java void someOp() { BigDecimal del_theta_1 = toDec(6); BigDecimal del_theta_2 = toDec(2); BigDecimal del_theta_m = toDec(0); del_theta_m = abs(del_theta_1.subtract(del_theta_2)) .divide(log(del_theta_1.divide(del_theta_2))); } Groovy void someOp() { def del_theta_1 = 6.0 def del_theta_2 = 2.0 def del_theta_m = 0.0 del_theta_m = Math.abs(del_theta_1 - del_theta_2) / Math.log(del_theta_1 / del_theta_2); } Scala def other(){ var del_theta_1 = toDec(6); var del_theta_2 = toDec(2); var del_theta_m = toDec(0); del_theta_m = ( abs(del_theta_1 - del_theta_2) / log(del_theta_1 / del_theta_2) ) } Note that in Java and Scala I used static imports. Java: Pros: it is Java Cons: no operator overloading (lots o methods), barely readable/codeable Groovy: Pros: default BigDecimal means no visible typing, least surprising BigDecimal support for all operations (division included) Cons: another language to learn Scala: Pros: has operator overloading for BigDecimal Cons: some surprising behaviour with division (fixed with Decimal128), another language to learn

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  • How do I handle the messages for a simple web-based live chat, on the server side?

    - by Carson Myers
    I'm building a simple live chat into a web application running on Django, but one thing I'm confused about is how I should store the messages between users. The chat will support multiple users, and a chat "session" is composed of users connected to one user that is the "host." The application is a sort of online document collaboration thing, so user X has a document, and users Y and Z would connect to user X to talk about the document, and that would be one chat session. If user Y disconnected for five minutes, and then signed back in and reconnected to user X, he should not get any of the messages shared between users X and Z while he was away. if users X, Y, and Z can have a chat session about user X's document, then users X and Y can connect to a simultaneous, but separate discussion about user Z's document. How should I handle this? Should I keep each message in the database? Each message would have an owner user and a target user (the host), and a separate table would be used to connect users with messages (which messages are visible to what users). Or should I store each session as an HTML file on the server, which messages get appended to? The problem is, I can't just send messages directly between clients. They have to be sent to the server in a POST request, and then each client has to periodically check for the messages in a GET request. Except I can't just have each message cleared after a client fetches it, because there could be multiple clients. How should I set this up? Any suggestions?

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  • AddEvenLister fires off immediately after being attached

    - by Diego
    I want to know how to correctly add an Event Listener like onClick to a dynamic div. Here’s my snippet: var $menu = new Array(2); createDiv('yes'); function createDiv(title) { var $class = 'menuLink'; var $title = 'title'; for(var i=0; i<$menu.length;i++) { $title = 'title'; var newdiv = document.createElement('div'); newdiv.setAttribute('class', $class); newdiv.setAttribute('id', 'item'+i); newdiv.addEventListener('onclick', clickHandle(newdiv.id),false); if (title) { newdiv.innerHTML = $title; } else { newdiv.innerHTML = "No Title"; } document.getElementById('menu').appendChild(newdiv); showMenu(); } } function clickHandle(e) { if(e == 'item0') { alert('Link is' + ' ' + e); }else{ alert('Another Link'); } } Here's my problem, the snippet works fine, It creates my divs, adds id's values and all, but the event fires off as soon as the event is attached, so while the for loop is creating the divs the alert window says: Link is item0, and immediately after this it says: Another Link. Am I misunderstanding this? (I used this method zillions of times in AS3 with the expected result, just attached a function waiting for a click). What I want is that my Divs wait for the user to click on them, not to fire off immediately after of being attached. Thanks for any hint on this one. Greetings. Ps. IE doesn't support addEventListener, but I want to resolve this before cross to the IE sea of madness, but I will appreciate the IE approach as well. - I tried "onclick" and just 'click' into the addEventListener line, both with the same result described above.

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  • import csv file/excel into sql database asp.net

    - by kiev
    Hi everyone! I am starting a project with asp.net visual studio 2008 / SQL 2000 (2005 in future) using c#. The tricky part for me is that the existing DB schema changes often and the import files columns will all have to me matched up with the existing db schema since they may not be one to one match on column names. (There is a lookup table that provides the tables schema with column names I will use) I am exploring different ways to approach this, and need some expert advice. Is there any existing controls or frameworks that I can leverage to do any of this? So far I explored FileUpload .NET control, as well as some 3rd party upload controls to accomplish the upload such as SlickUpload but the files uploaded should be < 500mb Next part is reading of my csv /excel and parsing it for display to the user so they can match it with our db schema. I saw CSVReader and others but for excel its more difficult since I will need to support different versions. Essentially The user performing this import will insert and/or update several tables from this import file. There are other more advance requirements like record matching but and preview of the import records, but I wish to get through understanding how to do this first. Update: I ended up using csvReader with LumenWorks.Framework for uploading the csv files.

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