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  • Wordpress dynamic navigation function for highlighting single post tabs

    - by user269959
    I am trying to write a function that i can reuse in my wordpress themes that will allow me to build robust dynamic navigation menus. Here is what i have so far: function tab_maker($page_name, $href, $tabname) { //opens <li> tag to allow active class to be inserted if tab is on proper page echo "<li"; //checks that we are on current page and highlights tab as active if so if(is_page($page_name)){ echo " class='current_page_item'>"; } //closes <li> tab if not active else { echo ">"; } //inserts the link as $href and the name of the tab to appear as $tabname then closes <li> echo "<a href=$href>$tabname</a>"; echo "</li>"; } This code works as expected except i cant enable it to highlight for a single blog post as the page names are dynamic. I know about the wordpress function is_single() which ive used to implement this feature in previous nav menus but i cant find a way to integrate it into this function. appreciate any help!

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  • Using ThreadPool.QueueUserWorkItem in ASP.NET in a high traffic scenario

    - by Michael Hart
    I've always been under the impression that using the ThreadPool for (let's say non-critical) short-lived background tasks was considered best practice, even in ASP.NET, but then I came across this article that seems to suggest otherwise - the argument being that you should leave the ThreadPool to deal with ASP.NET related requests. So here's how I've been doing small asynchronous tasks so far: ThreadPool.QueueUserWorkItem(s => PostLog(logEvent)) And the article is suggesting instead to create a thread explicitly, similar to: new Thread(() => PostLog(logEvent)){ IsBackground = true }.Start() The first method has the advantage of being managed and bounded, but there's the potential (if the article is correct) that the background tasks are then vying for threads with ASP.NET request-handlers. The second method frees up the ThreadPool, but at the cost of being unbounded and thus potentially using up too many resources. So my question is, is the advice in the article correct? If your site was getting so much traffic that your ThreadPool was getting full, then is it better to go out-of-band, or would a full ThreadPool imply that you're getting to the limit of your resources anyway, in which case you shouldn't be trying to start your own threads? Clarification: I'm just asking in the scope of small non-critical asynchronous tasks (eg, remote logging), not expensive work items that would require a separate process (in these cases I agree you'll need a more robust solution).

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  • How can I log and retrieve error messages from a client-side desktop app?

    - by KeyboardMonkey
    Update: The service-based answers below are most likely the way to go, I am also curious to see if there are any out-the-box solutions anyone has tried in the field. Our system uses a client-server architecture, and with more clients using it I'm thinking of better ways to log client application errors, and get them sent to us. Currently we just show a simple error message, with a button that preps an email (with the default system email client) and the clients send this on to our support address. This contains extra info like the stack trace. We also tried saving errors to a network share in the company, but I'm not too keen on that archaic solution either. Now there are only two businesses that refer to clients as users, and I'm sure some of ours support both lifestyles, as they just ignore the email button, and sends a full screen-shot wrapped nicely in a word document. Some factors I'm thinking of include A solution to log errors, like the contrived one above, A robust solution; Logging to a SQL database won't work; if that fails too, then what? Is at least semi-automated, preferably to the point where the logs reach my side. It copes with load, our client base is growing and the current solution, and our inboxes, won't hold up. Minimise installing extra 3rd party components on clients, I want to keep the SPOF to a min. I'd love to hear about any experience or suggestions you have on how I can implement such a solution. System Details It's a Microsoft .Net 2 based system with a SQL backend. Some users work remotely over the net, so network shares aren't always available (unless they VPN, which is awesomely slow at any rate). We have users across different companies, their DB's are hosted on-site. We have remote access to 90% of them.

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  • An alternative to reading input from Java's System.in

    - by dvanaria
    I’m working on the UVa Online Judge problem set archive as a way to practice Java, and as a way to practice data structures and algorithms in general. They give an example input file to submit to the online judge to use as a starting point (it’s the solution to problem 100). Input from the standard input stream (java.lang.System.in) is required as part of any solution on this site, but I can’t understand the implementation of reading from System.in they give in their example solution. It’s true that the input file could consist of any variation of integers, strings, etc, but every solution program requires reading basic lines of text input from System.in, one line at a time. There has to be a better (simpler and more robust) method of gathering data from the standard input stream in Java than this: public static String readLn(int maxLg) { byte lin[] = new byte[maxLg]; int lg = 0, car = -1; String line = “”; try { while (lg < maxLg) { car = System.in.read(); if ((car < 0) || (car == ‘\n’)) { break; } lin[lg++] += car; } } catch (java.io.IOException e) { return (null); } if ((car < 0) && (lg == 0)) { return (null); // eof } return (new String(lin, 0, lg)); } I’m really surprised by this. It looks like something pulled directly from K&R’s “C Programming Language” (a great book regardless), minus the access level modifer and exception handling, etc. Even though I understand the implementation, it just seems like it was written by a C programmer and bypasses most of Java’s object oriented nature. Isn’t there a better way to do this, using the StringTokenizer class or maybe using the split method of String or the java.util.regex package instead?

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  • C++: Check istream has non-space, non-tab, non-newline characters left without extracting chars

    - by KRao
    I am reading a std::istream and I need to verify without extracting characters that: 1) The stream is not "empty", i.e. that trying to read a char will not result in an fail state (solved by using peek() member function and checking fail state, then setting back to original state) 2) That among the characters left there is at least one which is not a space, a tab or a newline char. The reason for this is, is that I am reading text files containing say one int per line, and sometimes there may be extra spaces / new-lines at the end of the file and this causes issues when I try get back the data from the file to a vector of int. A peek(int n) would probably do what I need but I am stuck with its implementation. I know I could just read istream like: while (myInt << myIstream) {...} //Will fail when I am at the end but the same check would fail for a number of different conditions (say I have something which is not an int on some line) and being able to differentiate between the two reading errors (unexpected thing, nothing left) would help me to write more robust code, as I could write: while (something_left(myIstream)) { myInt << myIstream; if (myStream.fail()) {...} //Horrible things happened } Thank you!

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  • Switching from Sourcesafe - What to look for in a product

    - by asp316
    We're looking to move off of sourcesafe and on to a more robust source control system for our .Net apps. We're also looking for scripted/automated deployments. I'm a .Net developer (web and winforms). However, most of our development staff is RPG for the IBM iSeries and the devs use Aldon's LMI for source control and deployment. Our manager would prefer to stick with Aldon so all of our products are in the same system. However, I don't have experience with Aldon's products on the .Net side. I've used TFS and Subversion with Tortoise a bit, but not enough to recommend one or the other, especially in comparison to Aldon's product. Does anybody have experience with Aldon's products? If so, thoughts please? Also, other than the obvious things source control systems do, are there things I should avoid or are there must haves? I'm open to any system. A bit of background, I'm the only .Net dev in our company but I let operations do the deployments. I do want the ability to support concurrent checkouts if we hire a new dev.

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  • Versioned RDF store

    - by Mat
    Let me try rephrasing this: I am looking for a robust RDF store or library with the following features: Named graphs, or some other form of reification. Version tracking (probably at the named graph level). Privacy between groups of users, either at named graph or triple level. Human-readable data input and output, e.g. TriG parser and serialiser. I've played with Jena, Sesame, Boca, RDFLib, Redland and one or two others some time ago but each had its problems. Have any improved in the above areas recently? Can anything else do what I want, or is RDF not yet ready for prime-time? Reading around the subject a bit more, I've found that: Jena, nothing further Sesame, nothing further Boca does not appear to be maintained any more and seems only really designed for DB2. OpenAnzo, an open-source fork, appears more promising. RDFLib, nothing further Redland, nothing further Talis Platform appears to support changesets (wiki page and reference in Kniblet Tutorial Part 5) but it's a hosted-only service. Still may look into it though. SemVersion sounded promising, but appears to be stale.

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  • Add data to Django form class using modelformset_factory

    - by dean
    I have a problem where I need to display a lot of forms for detail data for a hierarchical data set. I want to display some relational fields as labels for the forms and I'm struggling with a way to do this in a more robust way. Here is the code... class Category(models.Model): name = models.CharField(max_length=160) class Item(models.Model): category = models.ForeignKey('Category') name = models.CharField(max_length=160) weight = models.IntegerField(default=0) class Meta: ordering = ('category','weight','name') class BudgetValue(models.Model): value = models.IntegerField() plan = models.ForeignKey('Plan') item = models.ForeignKey('Item') I use the modelformset_factory to create a formset of budgetvalue forms for a particular plan. What I'd like is item name and category name for each BudgetValue. When I iterate through the forms each one will be labeled properly. class BudgetValueForm(forms.ModelForm): item = forms.ModelChoiceField(queryset=Item.objects.all(),widget=forms.HiddenInput()) plan = forms.ModelChoiceField(queryset=Plan.objects.all(),widget=forms.HiddenInput()) category = "" < assign dynamically on form creation > item = "" < assign dynamically on form creation > class Meta: model = BudgetValue fields = ('item','plan','value') What I started out with is just creating a dictionary of budgetvalue.item.category.name, budgetvalue.item.name, and the form for each budget value. This gets passed to the template and I render it as I intended. I'm assuming that the ordering of the forms in the formset and the querset used to genererate the formset keep the budgetvalues in the same order and the dictionary is created correctly. That is the budgetvalue.item.name is associated with the correct form. This scares me and I'm thinking there has to be a better way. Any help would be greatly appreciated.

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  • Detecting death of spawned process using Window CRT

    - by Michael Tiller
    Executive summary: I need a way to determine whether a Windows process I've spawned via _spawnl and am communicating with using FDs from _pipe has died. Details: I'm using the low-level CRT function in Windows (_eof, _read) to communicate with a process that was spawned via a call to _spawnl (with the P_NOWAIT) flag. I'm using _pipe to create file descriptors to communicate with this spawned process and passing those descriptors (the FD #) to it on the command line. It is worth mentioning that I don't control the spawned process. It's a black box to me. It turns out that the process we are spawning occasionally crashes. I'm trying to make my code robust to this by detecting the crash. Unfortunately, I can't see a way to do this. It seems reasonable to me to expect that a call to _eof or _read on one of those descriptors would return an error status (-1) if the process had died. Unfortunately, that isn't the case. It appears that the descriptors have a life of their own independent of the spawned process. So even though the process on the other end is dead, I get no error status on the file descriptor I'm using to communicate with it. I've got the PID for the nested process (returned from the _spanwnl call) but I don't see anything I can do with that. My code works really well except for one thing. I can't detect whether the spawned process is simply busy computing me an answer or has died. If I can use the information from _pipe and _spawnl to determine if the spawned process is dead, I'll be golden. Suggestions very welcome. Thanks in advance. UPDATE: I found a fairly simple solution and added it as the selected answer.

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  • Floating point precision in Visual C++

    - by Luigi Giaccari
    HI, I am trying to use the robust predicates for computational geometry from Jonathan Richard Shewchuk. I am not a programmer, so I am not even sure of what I am saying, I may be doing some basic mistake. The point is the predicates should allow for precise aritmthetic with adaptive floating point precision. On my computer: Asus pro31/S (Core Due Centrino Processor) they do not work. The problem may stay in the fact the my computer may use some improvements in the floating point precision taht conflicts with the one used by Shewchuk. The author says: /* On some machines, the exact arithmetic routines might be defeated by the / / use of internal extended precision floating-point registers. Sometimes / / this problem can be fixed by defining certain values to be volatile, / / thus forcing them to be stored to memory and rounded off. This isn't / / a great solution, though, as it slows the arithmetic down. */ Now what I would like to know is that there is a way, maybe some compiler option, to turn off the internal extended precision floating-point registers. I really appriaciate your help

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  • Uncompress OpenOffice files for better storage in version control

    - by Craig McQueen
    I've heard discussion about how OpenOffice (ODF) files are compressed zip files of XML and other data. So making a tiny change to the file can potentially totally change the data, so delta compression doesn't work well in version control systems. I've done basic testing on an OpenOffice file, unzipping it and then rezipping it with zero compression. I used the Linux zip utility for my testing. OpenOffice will still happily open it. So I'm wondering if it's worth developing a small utility to run on ODF files each time just before I commit to version control. Any thoughts on this idea? Possible better alternatives? Secondly, what would be a good and robust way to implement this little utility? Bash shell that calls zip (probably Linux only)? Python? Any gotchas you can think of? Obviously I don't want to accidentally mangle a file, and there are several ways that could happen. Possible gotchas I can think of: Insufficient disk space Some other permissions issue that prevents writing the file or temporary files ODF document is encrypted (probably should just leave these alone; the encryption probably also causes large file changes and thus prevents efficient delta compression)

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  • Using Excel as front end to Access database (with VBA)

    - by Alex
    I am building a small application for a friend and they'd like to be able to use Excel as the front end. (the UI will basically be userforms in Excel). They have a bunch of data in Excel that they would like to be able to query but I do not want to use excel as a database as I don't think it is fit for that purpose and am considering using Access. [BTW, I know Access has its shortcomings but there is zero budget available and Access already on friend's PC] To summarise, I am considering dumping a bunch of data into Access and then using Excel as a front end to query the database and display results in a userform style environment. Questions: How easy is it to link to Access from Excel using ADO / DAO? Is it quite limited in terms of functionality or can I get creative? Do I pay a performance penalty (vs.using forms in Access as the UI)? Assuming that the database will always be updated using ADO / DAO commands from within Excel VBA, does that mean I can have multiple Excel users using that one single Access database and not run into any concurrency issues etc.? Any other things I should be aware of? I have strong Excel VBA skills and think I can overcome Access VBA quite quickly but never really done Excel / Access link before. I could shoehorn the data into Excel and use as a quasi-database but that just seems more pain than it is worth (and not a robust long term solution) Any advice appreciated. Alex

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  • The uncatchable exception

    - by chaiguy
    Another custom MarkupExtension binding question... This time, my converter is being called before DataContext is set on the target element. This isn't a big deal because it will get updated when DataContext eventually receives a value. What is causing problems is the NullReferenceException I'm getting because of DataContext being null. Even though I'm attempting to catch the exception in my value converter: try { return ( (MethodInfo)_member ).Invoke( parameter, null ); } catch { return Binding.DoNothing; } For some reason the debugger is still halting at this point. Now I'm thinking it could be because the exception is happening in another assembly from where it is being caught (I'm trying to package this in a reusable class library, and _member above points to a method in the application assembly). If I run my little test app without the debugger it works fine, however my application is a little more robust and has general exception handling which is getting triggered because of this. I'm wondering if there is just some attribute or something (or perhaps some reflection parameter I'm missing?) I can use to make the exception be caught like it's supposed to.

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  • Crash on iOS when system purges memory and closes a UIViewController

    - by Amiramix
    My application is crashing when one of the views is purged from memory because of low-memory condition. At least this is what I understand from the crashlog. It happens on numerous screens but only when opening a Facebook dialog (using the Facebook SDK). Basically, looks like the system sometimes runs out of memory when we need to present a Facebook dialog (e.g. to let user post something on the Facebook timeline). Date/Time: 2012-03-14 19:47:33.819 +0000 OS Version: iPhone OS 5.1 (9B176) Report Version: 104 Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: KERN_INVALID_ADDRESS at 0x30000008 Crashed Thread: 0 Thread 0 name: Dispatch queue: com.apple.main-thread Thread 0 Crashed: 0 libobjc.A.dylib 0x30f2bf78 objc_msgSend + 16 1 MyApp 0x00003c0e -LTBaseViewController viewDidUnload (LTBaseViewController.m:145) 2 MyApp 0x00004ea2 -LTBaseTableViewController viewDidUnload (LTBaseTableViewController.m:90) 3 UIKit 0x33766bd8 -[UIViewController unloadViewForced:] + 244 4 UIKit 0x338ae492 -[UIViewController purgeMemoryForReason:] + 58 5 Foundation 0x3071a4f8 __57-NSNotificationCenter addObserver:selector:name:object:_block_invoke_0 + 12 6 CoreFoundation 0x30e95540 ___CFXNotificationPost_block_invoke_0 + 64 7 CoreFoundation 0x30e21090 _CFXNotificationPost + 1400 8 Foundation 0x3068e3e4 -NSNotificationCenter postNotificationName:object:userInfo: + 60 9 Foundation 0x3068fc14 -NSNotificationCenter postNotificationName:object: + 24 10 UIKit 0x3387926a -UIApplication _performMemoryWarning + 74 11 UIKit 0x33879364 -UIApplication _receivedMemoryNotification + 168 12 libdispatch.dylib 0x36a12252 _dispatch_source_invoke + 510 13 libdispatch.dylib 0x36a0fb1e _dispatch_queue_invoke$VARIANT$up + 42 14 libdispatch.dylib 0x36a0fe64 _dispatch_main_queue_callback_4CF$VARIANT$up + 152 15 CoreFoundation 0x30e9c2a6 __CFRunLoopRun + 1262 16 CoreFoundation 0x30e1f49e CFRunLoopRunSpecific + 294 17 CoreFoundation 0x30e1f366 CFRunLoopRunInMode + 98 18 GraphicsServices 0x33fb6432 GSEventRunModal + 130 19 UIKit 0x336f5e76 UIApplicationMain + 1074 20 MyApp 0x00004818 main (main.m:16) 21 MyApp 0x000023b4 0x1000 + 5044 I checked and there are almost no memory leaks, e.g. when testing the app for an hour the total memory leaked was around 2-3Kb caused by some string-copying libraries. So I don't believe this is caused by the application. I guess that when the phone is not restarted for some time there are applications running in the background and when using Facebook SDK the memory becomes a problem and the system tries to recover the memory from random applications, including my application. My question is, how can I prevent this crash from happening? How should I handle unloadViewForced on a view controller to make the app more robust in low-memory conditions? And lastly, am I right that this crashlog suggests the crash occurred because the system tried to free memory and my application didn't handle it properly? Any help greatly appreciated.

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  • Design suggestion for expression tree evaluation with time-series data

    - by Lirik
    I have a (C#) genetic program that uses financial time-series data and it's currently working but I want to re-design the architecture to be more robust. My main goals are: sequentially present the time-series data to the expression trees. allow expression trees to access previous data rows when needed. to optimize performance of the data access while evaluating the expression trees. keep a common interface so various types of data can be used. Here are the possible approaches I've thought about: I can evaluate the expression tree by passing in a data row into the root node and let each child node use the same data row. I can evaluate the expression tree by passing in the data row index and letting each node get the data row from a shared DataSet (currently I'm passing the row index and going to multiple synchronized arrays to get the data). Hybrid: an immutable data set is accessible by all of the expression trees and each expression tree is evaluated by passing in a data row. The benefit of the first approach is that the data row is being passed into the expression tree and there is no further query done on the data set (which should increase performance in a multithreaded environment). The drawback is that the expression tree does not have access to the rest of the data (in case some of the functions need to do calculations using previous data rows). The benefit of the second approach is that the expression trees can access any data up to the latest data row, but unless I specify what that row is, I'll have to iterate through the rows and figure out which one is the last one. The benefit of the hybrid is that it should generally perform better and still provide access to the earlier data. It supports two basic "views" of data: the latest row and the previous rows. Do you guys know of any design patterns or do you have any tips that can help me build this type of system? Should I use a DataSet to hold and present the data, or are there more efficient ways to present rows of data while maintaining a simple interface? FYI: All of my code is written in C#.

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  • Utilizing Windows Handles without a forum.

    - by Scott Chamberlain
    I have a program that needs to sit in the background and when a user connects to a RDP session it will do some stuff then launch a program. when the program is closed it will do some housekeeping and logoff the session. The current way I am doing it is like this I have the terminal server launch this application. I have it set as a windows forms application and my code is this public static void Main() { //Do some setup work Process proc = new Process(); //setup the process proc.Start(); proc.WaitForExit(); //Do some housecleaning NativeMethods.ExitWindowsEx(0, 0); } I really like this because there is no item in the taskbar and there is nothing showing up in alt-tab. However to do this I gave up access to functions like void WndProc(ref Message m) So Now I can't listen to windows messages (Like WTS_REMOTE_DISCONNECT or WTS_SESSION_LOGOFF) and do not have a handle to use for for bool WTSRegisterSessionNotification(IntPtr hWnd, int dwFlags); I would like my code to be more robust so it will do the housecleaning if the user logs off or disconnects from the session before he closes the program. Any reccomendations on how I can have my cake and eat it too?

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  • Finding usage of jQuery UI in a big ugly codebase

    - by Daniel Magliola
    I've recently inherited the maintenance of a big, ugly codebase for a production website. Poke your eyes out ugly. And though it's big, it's mostly PHP code, it doesn't have much JS, besides a few "ajaxy" things in the UI. Our main current problem is that the site is just too heavy. Homepage weighs in at 1.6 Mb currently, so I'm trying to clean some stuff out. One of the main wasters is that every single page includes the jQuery UI library, but I don't think it's used at all. It's definitely not being used in the homepage and in most pages, so I want to only include the where necessary. I'm not really experienced with jQuery, i'm more of a Prototype guy, so I'm wondering. Is there anything I could search for that'd let me know where jQuery UI is being used? What i'm looking for is "common strings", component names, etc For example, if this was scriptaculous, i'd look for things like "Draggable", "Effect", etc. Any suggestions for jQuery UI? (Of course, if you can think of a more robust way of removing the tag from pages that don't use it without breaking everything, I'd love to hear about it) Thanks!! Daniel

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  • Automatically grow document view of NSScrollView using auto layout?

    - by Monolo
    Is there a simple way to get an NSScrollView to adapt to its document view changing size when using autolayout (the Lion feature)? I have tried to call both setNeedsUpdateConstraints: and setNeedsLayout: on the document view, the clip view and the scroll view, without any results. fittingSize of the document view reports the correct size. An NSPopover in conjunction with an NSViewController handles this nicely, with the popover growing and shrinking as needed, and I was hoping to get a similar simple and robust behaviour with the scroll view. I have checked the documentation for scroll views, but they don't seem to be updated to use autolayout. Edited to clarify: The problem I experience is that the document view, which holds subviews, is not re-sized when the subviews change their size, even if they call invalidateIntrinsicContentSize. The contents of the document view are hence clipped to the original size of the document view as they grow. The document view is created in a nib and set as the scroll view's document view in an awakeFromBib method. What I hoped to obtain was that the document view frame would automatically be adjusted to when its fittingSize changes, and the scrollbars updated accordingly. NSPopover does something similar - provided that the subviews of the content controller's view have the constraints set right and various content hugging values are high enough (higher than the hidden popover window's hight constraint priority, for one).

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  • Using the Microsoft Ajax Minifier with Web Setup project & Source Control

    - by Rob
    I've just started investigating the Microsoft Ajax Minifer 4.0 for use with a Visual Studio 2008 Web Application I work on. It's proven easy enough to hook it into the .csproj file so it produced .min.js files for all scripts, however I'm stumped as to how to integrate this with the Web Setup project & Source Control. Essentially what I want to do is have the resultant .min.js files included in the Web Setup project without having them included in Source Control because: Having to check them out prior to the build being executing is a pain (the minifier cannot modify them if they're not checked out). As they're created as a "build artifact" it just seems wrong to have them stored under source control. The only option I've managed to come across so far is to explicitly include the .min.js files as part of the Setup project by right clicking on the Web Setup project and choosing "Add File", and then having the relevant folder hierarchy duplicated in "File System on Target Machine" so that I can force the file to the correct location. This is neither elegant or simple/robust as: It requires me to manually add every minified js file to the Web Setup project by hand Maintain a copy of the relevant directory structure in both the Web Application project and the Web Setup project Remember to add any new js files minified versions to the Web Setup project Is there a better way of doing this?

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  • Old desktop programmer wants to create S+S project

    - by Craig
    I have an idea for a product that I want to be web-based. But because I live in Brasil, the internet is not always available so there needs to be a desktop component that is available for when the internet is down. Also, I have been a SQL programmer, a desktop application programmer using dBase, VB and Pascal, and I have created simple websites using HTML and website creation tools, such as Frontpage. So from my research, I think I have the following options; PHP, Ruby on Rails, Python or .NET for the programming side. MySQL for the DB. And Apache, or possibly IIS, for the webserver. I will probably start with a local ISP provider for the cloud servce. But then maybe move to something more "robust" and universal in the future, ie. Amazon, or Azure, or something along that line. My question then is this. What would you recommend for something like this? I'm sure that I have not listed all of the possibilities, but the ones I have researched and thought of. Thanks everyone, Craig

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  • Generating lognormally distributed random number from mean, coeff of variation

    - by Richie Cotton
    Most functions for generating lognormally distributed random numbers take the mean and standard deviation of the associated normal distribution as parameters. My problem is that I only know the mean and the coefficient of variation of the lognormal distribution. It is reasonably straight forward to derive the parameters I need for the standard functions from what I have: If mu and sigma are the mean and standard deviation of the associated normal distribution, we know that coeffOfVar^2 = variance / mean^2 = (exp(sigma^2) - 1) * exp(2*mu + sigma^2) / exp(mu + sigma^2/2)^2 = exp(sigma^2) - 1 We can rearrange this to sigma = sqrt(log(coeffOfVar^2 + 1)) We also know that mean = exp(mu + sigma^2/2) This rearranges to mu = log(mean) - sigma^2/2 Here's my R implementation rlnorm0 <- function(mean, coeffOfVar, n = 1e6) { sigma <- sqrt(log(coeffOfVar^2 + 1)) mu <- log(mean) - sigma^2 / 2 rlnorm(n, mu, sigma) } It works okay for small coefficients of variation r1 <- rlnorm0(2, 0.5) mean(r1) # 2.000095 sd(r1) / mean(r1) # 0.4998437 But not for larger values r2 <- rlnorm0(2, 50) mean(r2) # 2.048509 sd(r2) / mean(r2) # 68.55871 To check that it wasn't an R-specific issue, I reimplemented it in MATLAB. (Uses stats toolbox.) function y = lognrnd0(mean, coeffOfVar, sizeOut) if nargin < 3 || isempty(sizeOut) sizeOut = [1e6 1]; end sigma = sqrt(log(coeffOfVar.^2 + 1)); mu = log(mean) - sigma.^2 ./ 2; y = lognrnd(mu, sigma, sizeOut); end r1 = lognrnd0(2, 0.5); mean(r1) % 2.0013 std(r1) ./ mean(r1) % 0.5008 r2 = lognrnd0(2, 50); mean(r2) % 1.9611 std(r2) ./ mean(r2) % 22.61 Same problem. The question is, why is this happening? Is it just that the standard deviation is not robust when the variation is that wide? Or have a screwed up somewhere?

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  • error detection/correction/recovery in serial protocols

    - by Jason S
    I have some designing to do for a serial protocol and am running into some questions that I figure must have been considered elsewhere. So I'm wondering if there are some recommendations for best practices in designing serial protocols. (Please either state a fact that is easily verifiable, or cite a reputable source if you make a claim.) General recommendations for websites/books are also welcome. In particular I have to deal with issues like parsing a stream of bytes into packets verifying a packet is correct (easy with a CRC, for instance) identifying reasonable types of errors that can occur (e.g. in a point-to-point serial stream, sporadic single bit errors, and dropped series of bytes, are both likely, but extra phantom bytes are unlikely; whereas with a record stored in flash memory or on a disk drive the types of errors that predominate are different) error correction or recovery (if I detect an error in a packet, can I correct it? If not, can I resync to the boundary of the next packet?) how to make variable-length packets robust to error correction / recovery. Any suggestions?

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  • Dynamic columns/rows

    - by Fuego DeBassi
    Wondering--does anyone know of any good articles explaining the CSS technique allowing multiple instances of a class to flow down the page relative to the items above it. Not explaining it that well. Veerle' Pierter's does it on this page: http://veerle.duoh.com/belgiangraphicdesign Although I'm not sure I want to use a technique like her's that requires entering of the height per element via her EE installation. I made a little graphic of what I am trying to acheive; http://cl.ly/71163510ce9d294f9f33 The key is I need a robust technique for doing it. Something where the markup could be as simple as; <div class="box"> Number 1 </div> <div class="box"> Number 2 </div> <div class="box"> Number 3 </div> <div class="box"> Number 4 </div> <div class="box"> Number 5 </div> ... Would love any pointers in the right direction.

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  • Modify request querystring paramaters to build a new link without resorting to string manipulation

    - by Andrew M
    Hi All, I want to dynamically populate a link with the URI of the current request, but set one specific query string parameter. All other querystring paramaters (if there are any) should be left untouched. And I don't know in advance what they might be. Eg, imagine I want to build a link back to the current page, but with the querystring parameter "valueOfInterest" always set to be "wibble" (I'm doing this from the code-behind of an aspx page, .Net 3.5 in C# FWIW). Eg, a request for either of these two: /somepage.aspx /somepage.aspx?valueOfInterest=sausages would become: /somepage.aspx?valueOfInterest=wibble And most importantly (perhaps) a request for: /somepage.aspx?boring=something /somepage.aspx?boring=something&valueOfInterest=sausages would preserve the boring params to become: /somepage.aspx?boring=something&valueOfInterest=wibble Caveats: I'd like to avoid string manipulation if there's something more elegant in asp.net that is more robust. However if there isn't something more elegant, so be it. I've done (a little) homework: I found a blog post which suggested copying the request into a local HttpRequest object, but that still has a read-only collection for the querystring params. I've also had a look at using a URI object, but that doesn't seem to have a querystring

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  • Reading data from an open HTTP stream

    - by allenjones
    Hi, I am trying to use the .NET WebRequest/WebResponse classes to access the Twitter streaming API here "http://stream.twitter.com/spritzer.json". I need to be able to open the connection and read data incrementally from the open connection. Currently, when I call WebRequest.GetResponse method, it blocks until the entire response is downloaded. I know there is a BeginGetResponse method, but this will just do the same thing on a background thread. I need to get access to the response stream while the download is still happening. This just does not seem possible to me with these classes. There is a specific comment about this in the Twitter documentation: "Please note that some HTTP client libraries only return the response body after the connection has been closed by the server. These clients will not work for accessing the Streaming API. You must use an HTTP client that will return response data incrementally. Most robust HTTP client libraries will provide this functionality. The Apache HttpClient will handle this use case, for example." They point to the Appache HttpClient, but that doesn't help much because I need to use .NET. Any ideas whether this is possible with WebRequest/WebResponse, or do I have to go for lower level networking classes? Maybe there are other libraries that will allow me to do this? Thx Allen

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