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  • about the post_save signal and created argument

    - by panchicore
    the docs says: post_save django.db.models.signals.post_save created A boolean; True if a -new- record was create. and I have this: from django.db.models.signals import post_save def handle_new_user(sender, instance, created, **kwargs): print "--------> save() "+str(created) post_save.connect(handle_new_user, sender=User) when I do in shell: u = User(username="cat") u.save() >>> --------> save() True u.username = "dog" u.save() >>> --------> save() True I expect a -------- save() False when I save() the second time because is an update? not?

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  • How can I listen for the deletion of a ProjectItem via DTE?

    - by Will
    I've got a designer that relies on the existence of other solution items. If one of those items is deleted the designer crashes and you have to edit as XML to fix. Not exactly user friendly. I do, however, have the DTE object representing the instance of Visual Studio, as well as the ProjectItems I am dependent on. Is it possible to, somewhere in the depths of the DTE, register a listener for the deletion of that ProjectItem? And, if so, How would I do it?

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  • Should I create protected constructor for my singleton classes?

    - by Vijay Shanker
    By design, in Singleton pattern the constructor should be marked private and provide a creational method retuning the private static member of the same type instance. I have created my singleton classes like this only. public class SingletonPattern {// singleton class private static SingletonPattern pattern = new SingletonPattern(); private SingletonPattern() { } public static SingletonPattern getInstance() { return pattern; } } Now, I have got to extend a singleton class to add new behaviors. But the private constructor is not letting be define the child class. I was thinking to change the default constructor to protected constructor for the singleton base class. What can be problems, if I define my constructors to be protected? Looking for expert views....

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  • Extra characters Extracted with XPath and Python (html)

    - by Nacari
    I have been using XPath with scrapy to extract text from html tags online, but when I do I get extra characters attached. An example is trying to extract a number, like "204" from a <td> tag and getting [u'204']. In some cases its much worse. For instance trying to extract "1 - Mathoverflow" and instead getting [u'\r\n\t\t 1 \u2013 MathOverflow\r\n\t\t ']. Is there a way to prevent this, or trim the strings so that the extra characters arent a part of the string? (using items to store the data). It looks like it has something to do with formatting, so how do I get xpath to not pick up that stuff?

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  • Django models & Python class attributes

    - by Geo
    The tutorial on the django website shows this code for the models: from django.db import models class Poll(models.Model): question = models.CharField(max_length=200) pub_date = models.DateTimeField('date published') class Choice(models.Model): poll = models.ForeignKey(Poll) choice = models.CharField(max_length=200) votes = models.IntegerField() Now, each of those attribute, is a class attribute, right? So, the same attribute should be shared by all instances of the class. A bit later, they present this code: class Poll(models.Model): # ... def __unicode__(self): return self.question class Choice(models.Model): # ... def __unicode__(self): return self.choice How did they turn from class attributes into instance attributes? Did I get class attributes wrong?

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  • zsh for loop exclusion

    - by ABach
    This is somewhat of a simple question, but for the life of me, I cannot figure out how to exclude something from a zsh for loop. For instance, let's say we have this: for $package in /home/user/settings/* do # do stuff done Let's say that in /home/user/settings/, there is a particular directory ("os") that I want to ignore. Logically, I tried the following variations: for $package in /home/user/settings/^os (works w/ "ls", but not with a foor loop) for $package in /home/user/settings/*^os for $package in /home/user/settings/^os* ...but none of those seem to work. Could someone steer my syntax in the right direction?

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  • Display relative time in hour, day, month and year

    - by JohnJohnGa
    I wrote a function toBeautyString(epoch) : String which given a epoch, return a string which will display the relative time from now in hour and minute For instance: // epoch: 1346140800 -> Tue, 28 Aug 2012 05:00:00 GMT // and now: 1346313600 -> Thu, 30 Aug 2012 08:00:00 GMT toBeautyString(1346140800) -> "2 days and 3 hours ago" I want now to extend this function to month and year, so it will be able to print: 2 years, 1 month, 3 days and 1 hour ago Only with epoch without any external libraries. The purpose of this function is to give to the user a better way to visualize the time in the past. I found this: Calculating relative time but the granularity is not enough.

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  • linux's fork and system resources

    - by Dmitry Bespalov
    Suppose I have following code in linux: int main() { FILE* f = fopen("file.txt", "w"); fork(); fwrite("A", 1, 1, f); fclose(f); return 0; } What I know about fork from documentation, is that it makes the copy of current process. It copies state of the memory as well, so *f should be equal in both instances. But what happens with system resources, such as a file handle? In this example I open the file with write intentions, so only one instance can write into file, right? Which of the instances will actually write into file? Who should care further about the file handle, and call fclose() ?

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  • InnoDB not supported by webhost. What now?

    - by Peter Perhác
    I was developing a small WAMP web application on my laptop, where I have an instance of mySQL running and I chose InnoDB for my DB engine. After several weeks' development I wanted to make it available to the public and found out the database server provided by my web host does not support InnoDB, only MyISAM. The create-and-populate script generated from the innoDB schema on my laptop, when executed against the live database, can manage to create individual TABLES but then runs into problems creating the VIEWs. Are views not supported in MyISAM? I know FOREIGN KEYs are not. That's very much why I made the choice of InnoDB... What are my chances of making my innoDB schema design work with myISAM? Is there any straightforward way of converting the whole schema from one storage engine to the other? Should I look for another web host that does provide a mysql db that supports innoDB?

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  • Deserialize array values to .NET properties using DataContractJsonSerializer

    - by James Cadd
    I'm working with the DataContractJsonSerializer in Silverlight 4 and would like to deserialize the following JSON: { "collectionname":"Books", "collectionitems": [ ["12345-67890",201, "Book One"], ["09876-54321",45, "Book Two"] ] } Into classes like the following: class BookCollection { public string collectionname { get; set; } public List<Book> collectionitems { get; set; } } class Book { public string Id { get; set; } public int NumberOfPages { get; set; } public string Title { get; set; } } What's the proper place to extend DataContractJsonSerializer to map the unnamed first array element in "collectionitems" to the Id property of the Book class, the second element to the NumberOfPages property and the final element to Title? I don't have control over the JSON generation in this instance and would like the solution to work with the Silverlight subset of .NET. It would be great if the solution could perform the reverse for serialization as well.

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  • change the return of to_param by action? or, terribly broken edit action if perma-url is returned in

    - by Stacia
    I did some stuff to have to_param return a perma-url so I'd have seo friendly links. Upon creation and update it will generate and return the perma-url in a to_param method that I put in the model. However this causing me some grief in other areas. I have a form that looks like this: <% @apps.each do |app| %> <% fields_for "[id][]", app do |fields| %> .... this fails terribly since it tries to insert the perma-url in place of the id. If I could just restrict to_param by action, that could solve things. If I change app to app.id, that fails since I have stuff like this: fields.check_box :is_featured . I suppose I could get the app instance, but that feels hacky. Again please excuse my lack of rails-foo ;)

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  • Binning into timeslots - Is there a better way than using list comp?

    - by flyingcrab
    I have a dataset of events (tweets to be specific) that I am trying to bin / discretize. The following code seems to work fine so far (assuming 100 bins): HOUR = timedelta(hours=1) start = datetime.datetime(2009,01,01) z = [dt + x*HOUR for x in xrange(1, 100)] But then, I came across this fateful line at python docs 'This makes possible an idiom for clustering a data series into n-length groups using zip(*[iter(s)]*n)'. The zip idiom does indeed work - but I can't understand how (what is the * operator for instance?). How could I use to make my code prettier? I'm guessing this means I should make a generator / iterable for time that yields the time in graduations of an HOUR?

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  • AsyncTask Threading Rule - Can it really only be used once?

    - by stormin986
    In the documentation on AsyncTask it gives the following as a rule related to threading: The task can be executed only once (an exception will be thrown if a second execution is attempted.) All this means is that you have to create a new instance of the class every time you want to use it, right? In other words, it must be done like this: new DownloadFilesTask().execute(url1, url2, url3); new DownloadFilesTask().execute(url4, url5, url6); Or conversely, you can NOT do the following: DownloadFilesTask dfTask = new DownloadFilesTask(); dfTask().execute(url1, url2, url3); dfTask().execute(url4, url5, url6); Can someone verify this is an accurate interpretation? I realize I pretty much just answered this for myself as I was typing this out... But it wasn't immediately obvious to me so I think this would be useful to have posted nonetheless.

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  • iPhone Application: force landscape mode, strange behaviour...?

    - by David Lawson
    This is a method I use to switch display views, based on a string passed (for example you could pass MainMenuViewController to switch views to a new instance of that class): - (void)displayView:(NSString *)newView { NSLog(@"%@", newView); [[currentView view] removeFromSuperview]; [currentView release]; UIViewController *newView = [[NSClassFromString(newView) alloc] init]; [[newView view] setFrame:CGRectMake(0, 0, 320, 460)]; [self setCurrentView:newView]; [[self view] addSubview:[currentView view]]; } I have my application forced into landscape view (.plist and -shouldRotate), but if you look in the code: [[newView view] setFrame:CGRectMake(0, 0, 320, 460)]; I have to set the frame of the newView to a portrait frame for the view to be displayed correctly - otherwise, for example, a button on the new view can only be pressed in certain parts of the screen (rectangle up the top), unresponsive anywhere else. Even though in all my NIB files they are set to landscape.

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  • What issues carry the highest risk in a software project?

    - by Mehrdad Afshari
    Clearly, software projects are different from other industries in terms of many things like for instance, quality assurance, project progress measurement, and many other things. Unique characteristics of software projects also makes the risk management process unique. Lots of issues in a project might lead it to unacceptable delay or failure to deliver business value. They might even make a complete disaster in the project. What are the deadliest risk factors in a software project? How to analyze, prevent and handle them? Particularly, I'm interested in the issues that you can detect from the beginning and you should keep an eye on (for example, you might be told about a third-party API that the current application uses and lacks documentation). Please share your experiences if they are relevant.

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  • Interpolating height for a point inside a grid based on a discrete height function.

    - by fastrack20
    Hi, I have been wracking my brain to come up with a solution to this problem. I have a lookup table that returns height values for various points (x,z) on the grid. For instance I can calculate the height at A, B, C and D in Figure 1. However, I am looking for a way to interpolate the height at P (which has a known (x,z)). The lookup table only has values at the grid intervals, and P lies between these intervals. I am trying to calculate values s and t such that: A'(s) = A + s(C-A) B'(t) = B + t(P-B) I would then use the these two equations to find the intersection point of B'(t) with A'(s) to find a point X on the line A-C. With this I can calculate the height at this point X and with that the height at point P. My issue lies in calculating the values for s and t. Any help would be greatly appreciated.

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  • Define the base class or base functionality of a dynamic proxy (e.g. Castle, LinFu)

    - by Graham
    Hi, I've asked this in the NHibernate forumns but I think this is more of a general question. NHibernate uses proxy generators (e.g. Castle) to create its proxy. What I'd like to do is to extend the proxy generated so that it implements some of my own custom behaviour (i.e. a comparer). I need this because the following standard .NET behaviour fails to produce the correct results: //object AC is a concrete class collection.Contains(AC) = true //object AP is a proxy with the SAME id and therefore represents the same instance as concrete AC collection.Contains(AP) = false If my comparer was implemented by AP (i.e. do id's match) then collection.Contains(AP) would return true, as I'd expect if proxies were implicit. (NB: For those who say NH inherits from your base class, then yes it does, but NH can also inherit from an interface - which is what we're doing) I'm not at all sure this is possible or where to start. Is this something that can be done in any of the common proxy generators that NH uses?

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  • my .jar file won't do anything.

    - by David
    I created a program that more or less holds an array of strings as an object and randomly prints one. so basicaly class Happy { string[] namestrings = new string[#] constructor() { fill with some strings} public static void main (String[]arg) { create instance of class do some junk with it method that prints it } method that prints it {} another method } when i compile and run it on the command line it works fine but when on the comand line i type in jar -cf Happy.jar Fun.class i get a .jar file called Happy and when i click on it i get an error message that reads "the java Jar file happy could not be launched read the consol for possible error messages" I have a mac i'm running lepord if that makes a diference. Whats going on?

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  • What Use are Threads Outside of Parallel Problems on MultiCore Systesm?

    - by Robert S. Barnes
    Threads make the design, implementation and debugging of a program significantly more difficult. Yet many people seem to think that every task in a program that can be threaded should be threaded, even on a single core system. I can understand threading something like an MPEG2 decoder that's going to run on a multicore cpu ( which I've done ), but what can justify the significant development costs threading entails when you're talking about a single core system or even a multicore system if your task doesn't gain significant performance from a parallel implementation? Or more succinctly, what kinds of non-performance related problems justify threading? Edit Well I just ran across one instance that's not CPU limited but threads make a big difference: TCP, HTTP and the Multi-Threading Sweet Spot Multiple threads are pretty useful when trying to max out your bandwidth to another peer over a high latency network connection. Non-blocking I/O would use significantly less local CPU resources, but would be much more difficult to design and implement.

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  • How can I tell Visual Studio to NOT BREAK on a particular exception?

    - by Noel Kennedy
    I have a particular type of exception that I would like Visual Studio to not catch with the Exception Assistant. Essentially I would like it just to let my normal exception handling infrastructure deal with it. The exception is an inheritor of System.Exception which I wrote and have the source code for. Any where this is thrown I want VS to not catch it, ie it is not useful to just supress a single throw new BlahException(); in code. This is because the exception is thrown a lot, and I don't want to have to supress every single instance individually. In case it makes a difference I am on Visual Studio 2010 Ultimate, Framework 3.5 SP1.

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  • @media queries - one rule overrides another?

    - by John
    I have multiple @media queries all working fine but as soon as i put in a higher max screen-width than 1024px the rules for the higher width gets applied to everything. @media screen and (max-width: 1400px) { #wrap { width: 72%; } } @media screen and (max-width: 1024px) { #slider h2 { width: 100%; } #slider img { margin: 60px 0.83333333333333% 0 2.08333333333333%; } .recent { width: 45.82%; margin: 10px 2.08333333333334% 0 1.875%; } } as you can see 1024px (and also the 800px max-width query) do not change the #wrap width and work fine. As soon as i add the 1400px max-width query it changes them to 72% for ALL sizes and does the same for any element - for instance if i set #slider img to have a margin of 40px it will show at ALL sizes even though it is only in the max-width of 1400px. Am i missing something really obvious? Been trying to work this out for the past 2 days! Thanks, John

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  • Matching an IP address with an IP range?

    - by Legend
    I have a MySQL table setup as follows: +---------------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+-------------+------+-----+---------+----------------+ | ipaddress_s | varchar(15) | YES | MUL | NULL | | | ipaddress_e | varchar(16) | YES | | NULL | | +---------------+-------------+------+-----+---------+----------------+ where, ipaddress_s and ipaddress_e look something like: 4.100.159.0-4.100.159.255 Now is there a way I can actually get the row that contains a given IP address? For instance, given the IP address: "4.100.159.5", I want the above row to be returned. So I am trying for a query that looks something like this (but of course this is wrong because in the following I am considering IPs as strings): SELECT * FROM ranges WHERE ipaddress_s<"4.100.159.5" AND ipaddress_e>"4.100.159.5" Any suggestions?

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  • Back Button gets Disabled on IE 7,8 for an ASP.NET site

    - by timeitquery
    In an ASP.NET 3.5 website we are noticing that the back button is not working properly. If the user does several postbacks (say 10 times), and than starts pressing back button - the back button gets disabled before the user gets through all the pages. The site does not use AJAX.net. I can reproduce the issue on IE 7 and 8 almost always. The problem seems to be with some sort of limit IE has on History Cache for a given tab/instance. In the tests I did the post request to the server are large - around 83k, and the responses are are round 300k. It seems that with these request sizes the history does not hold more than 4 items. The moment I get to the 5 post, the first item i had selected is dropped.

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  • How can I tell Visual Studio to not catch a particular exception?

    - by Noel Kennedy
    I have a particular type of exception that I would like Visual Studio to not catch with the Exception Assistant. Essentially I would like it just to let my normal exception handling infrastructure deal with it. The exception is an inheritor of System.Exception which I wrote and have the source code for. Any where this is thrown I want VS to not catch it, ie it is not useful to just supress a single throw new BlahException(); in code. This is because the exception is thrown a lot, and I don't want to have to supress every single instance individually. In case it makes a difference I am on Visual Studio 2010 Ultimate, Framework 3.5 SP1.

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