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• How to tell what name RIA Services/EF Model uses for Associations?

  - by Nick Gotch

  Hi, I'm working on a C#.NET 3.5 WCF RIA Services app and having an issue with my Entity Framework model. My entity Foo is mapped to a DB table and has a primary key called FooId. My Bar is mapped to a DB view. I've selectively designed this view to generate a composite key in the EF using two of the columns (by making sure they were non-nullable and the others are all nullable. This was done using NULLIF and ISNULL in the view design.) I'm able to add this view to the model with no problem but I keep running into an issue when I try to map an association between the two. Foo should contain many Bars but I keep getting the following error when I add the association: Unable to retrieve AssociationType for association 'FK_Bar_Foo' According to this page, it looks like this might work if I can properly name the association (since RIA Services looks for specific names.) I've tried several variants of names that match the pattern of other associations with no success. Does anyone know if there's a place I can look to find out what name it's looking for? Thanks,

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• Input validation in WPF

  - by irfanali-wpfexpert

  i am developing an application in wpf using MVVM design pattern. i have a listbox when an item is slected then a dialog is open having the same record in editable mode. this dialog is binded with the selected item of the list. i have apply the validation rule for textbox using IDataErrorInfo. when the user update a record on dialogbox then at every key press, the selected record in listbox is also changed. if the user press save button then i submit changes to database. but if user click cancel button then i do not submit changes to database but the list box is updated with the current updation in GUI. when i refresh the list then old value appears again. My requirement is to update the listbox only when the user hit the save button but not on every key press on dialog box. I first fill the generic list with the linq to sql classes then bind the listbox with it. Please let me know what i have to do. Thanks in advance

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• How to get a handle on all this middleware?

  - by jkohlhepp

  My organization has recently been wrestling the question of whether we should be incorporating different middleware products / concepts into our applications. Products we are looking at are things like Pegasystems, Oracle BPM / BPEL, BizTalk, Fair Isaac Blaze, etc., etc., etc. But I'm having a hard time getting a handle on all this. Before I go forward with evaluating the usefulness (positive or negative) of these different products I'm trying to get an understanding of all the different concepts in this space. I'm overwhelmed with an alphabet soup of BPM, ESB, SOA, CEP, WF, BRE, ERP, etc. Some products seem to cover one or more of those aspects, others focus on doing one. The terms all seem very ambiguous and conflated with each other. Is there a good resource out there to get a handle on all these different middleware concepts / patterns? A book? A website? An article that sums it up well? Bonus points if there is a resource that maps the various popular products into which pattern(s) they address. Thanks, ~ Justin

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• Create inherited class from base class

  - by Raj

  public class Car { private string make; private string model; public Car(string make, string model) { this.make = make; this.model = model; } public virtual void Display() { Console.WriteLine("Make: {0}", make); Console.WriteLine("Model: {0}", model); } public string Make { get{return make;} set{make = value;} } public string Model { get{return model;} set{model = value;} } } public class SuperCar:Car { private Car car; private int horsePower; public SuperCar(Car car) { this.car = car; } public int HorsePower { get{return horsePower;} set{horsepower = value;} } public override void Display() { base.Display(); Console.WriteLine("I am a super car"); } When I do something like Car myCar = new Car("Porsche", "911"); SuperCar mySupcar = new SuperCar(myCar); mySupcar.Display(); I only get "I am a supercar" but not the properties of my base class. Should I explicitly assign the properties of my base class in the SuperCar constructor? In fact I'm trying Decorator pattern where I want a class to add behaviour to a base class.

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• Should a Perl constructor return an undef or a "invalid" object?

  - by DVK

  Question: What is considered to be "Best practice" - and why - of handling errors in a constructor?. "Best Practice" can be a quote from Schwartz, or 50% of CPAN modules use it, etc...; but I'm happy with well reasoned opinion from anyone even if it explains why the common best practice is not really the best approach. As far as my own view of the topic (informed by software development in Perl for many years), I have seen three main approaches to error handling in a perl module (listed from best to worst in my opinion): Construct an object, set an invalid flag (usually "is_valid" method). Often coupled with setting error message via your class's error handling. Pros: Allows for standard (compared to other method calls) error handling as it allows to use $obj->errors() type calls after a bad constructor just like after any other method call. Allows for additional info to be passed (e.g. 1 error, warnings, etc...) Allows for lightweight "redo"/"fixme" functionality, In other words, if the object that is constructed is very heavy, with many complex attributes that are 100% always OK, and the only reason it is not valid is because someone entered an incorrect date, you can simply do "$obj->setDate()" instead of the overhead of re-executing entire constructor again. This pattern is not always needed, but can be enormously useful in the right design. Cons: None that I'm aware of. Return "undef". Cons: Can not achieve any of the Pros of the first solution (per-object error messages outside of global variables and lightweight "fixme" capability for heavy objects). Die inside the constructor. Outside of some very narrow edge cases, I personally consider this an awful choice for too many reasons to list on the margins of this question. UPDATE: Just to be clear, I consider the (otherwise very worthy and a great design) solution of having very simple constructor that can't fail at all and a heavy initializer method where all the error checking occurs to be merely a subset of either case #1 (if initializer sets error flags) or case #3 (if initializer dies) for the purposes of this question. Obviously, choosing such a design, you automatically reject option #2.

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• "Illegal characters in path." Visual Studio WinForm Design View

  - by jacksonakj

  I am putting together a lightweight MVP pattern for a WinForms project. Everything compiles and runs fine. However when I attempt to open the WinForm in design mode in Visual Studio I get a "Illegal characters in path" error. My WinForm is using generics and inheriting from a base Form class. Is there a problem with using generics in a WinForm? Here is the WinForm and base Form class. public partial class TapsForm : MvpForm<TapsPresenter, TapsFormModel>, ITapsView { public TapsForm() { InitializeComponent(); } public TapsForm(TapsPresenter presenter) :base(presenter) { InitializeComponent(); UpdateModel(); } public IList<Taps> Taps { set { gridTaps.DataSource = value; } } private void UpdateModel() { Model.RideId = Int32.Parse(cboRide.Text); Model.Latitude = Double.Parse(txtLatitude.Text); Model.Longitude = Double.Parse(txtLongitude.Text); } } Base form MvpForm: public class MvpForm<TPresenter, TModel> : Form, IView where TPresenter : class, IPresenter where TModel : class, new() { private readonly TPresenter presenter; private TModel model; public MvpForm() { } public MvpForm(TPresenter presenter) { this.presenter = presenter; this.presenter.RegisterView(this); } protected override void OnLoad(EventArgs e) { base.OnLoad(e); if (presenter != null) presenter.IntializeView(); } public TModel Model { get { if (model == null) throw new InvalidOperationException("The Model property is currently null, however it should have been automatically initialized by the presenter. This most likely indicates that no presenter was bound to the control. Check your presenter bindings."); return model; } set { model = value;} } }

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• ASP.NET: aggregating validators in a user control

  - by orsogufo

  I am developing a web application where I would like to perform a set of validations on a certain field (an account name in the specific case). I need to check that the value is not empty, matches a certain pattern and is not already used. I tried to create a UserControl that aggregates a RequiredFieldValidator, a RegexValidator and a CustomValidator, then I created a ControlToValidate property like this: public partial class AccountNameValidator : System.Web.UI.UserControl { public string ControlToValidate { get { return ViewState["ControlToValidate"] as string; } set { ViewState["ControlToValidate"] = value; AccountNameRequiredFieldValidator.ControlToValidate = value; AccountNameRegexValidator.ControlToValidate = value; AccountNameUniqueValidator.ControlToValidate = value; } } } However, if I insert the control on a page and set ControlToValidate to some control ID, when the page loads I get an error that says Unable to find control id 'AccountName' referenced by the 'ControlToValidate' property of 'AccountNameRequiredFieldValidator', which makes me think that the controls inside my UserControl cannot resolve correctly the controls in the parent page. So, I have two questions: 1) Is it possible to have validator controls inside a UserControl validate a control in the parent page? 2) Is it correct and good practice to "aggregate" multiple validator controls in a UserControl? If not, what is the standard way to proceed?

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• Detecting Xml namespace fast

  - by Anna Tjsoken

  Hello there, This may be a very trivial problem I'm trying to solve, but I'm sure there's a better way of doing it. So please go easy on me. I have a bunch of XSD files that are internal to our application, we have about 20-30 Xml files that implement datasets based off those XSDs. Some Xml files are small (<100Kb), others are about 3-4Mb with a few being over 10Mb. I need to find a way of working out what namespace these Xml files are in order to provide (something like) intellisense based off the XSD. The implementation of this is not an issue - another developer has written the code for this. But I'm not sure the best (and fastest!) way of detecting the namespace is without the use of XmlDocument (which does a full parse). I'm using C# 3.5 and the documents come through as a Stream (some are remote files). All the files are *.xml (I can detect if it was extension based) but unfortunately the Xml namespace is the only way. Right now I've tried XmlDocument but I've found it to be innefficient and slow as the larger documents are awaiting to be parsed (even the 100Kb docs). public string GetNamespaceForDocument(Stream document); Something like the above is my method signature - overloads include string for "content". Would a RegEx (compiled) pattern be good? How does Visual Studio manage this so efficiently? Another college has told me to find a fast Xml parser in C/C++, parse the content and have a stub that gives back the namespace as its slower in .NET, is this a good idea?

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• Automatically generating Regex from set of strings residing in DB C#

  - by Muhammad Adeel Zahid

  Hello Everyone i have about 100,000 strings in database and i want to if there is a way to automatically generate regex pattern from these strings. all of them are alphabetic strings and use set of alphabets from English letters. (X,W,V) is not used for example. is there any function or library that can help me achieve this target in C#. Example Strings are KHTK RAZ given these two strings my target is to generate a regex that allows patterns like (k, kh, kht,khtk, r, ra, raz ) case insensitive of course. i have downloaded and used some C# applications that help in generating regex but that is not useful in my scenario because i want a process in which i sequentially read strings from db and add rules to regex so this regex could be reused later in the application or saved on the disk. i m new to regex patterns and don't know if the thing i m asking is even possible or not. if it is not possible please suggest me some alternate approach. Any help and suggestions are highly appreciated. regards Adeel Zahid

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• Drawing lines between views in a TableLayout

  - by RiThBo

  Firstly - sorry if you saw my other question which I deleted. My question was flawed. Here is a better version If I have two views, how do I draw a (straight) line between them when one of them is touched? The line needs to be dynamic so it can follow the finger until it reaches the second view where it "locks on". So, when view1 is touched a straight line is drawn which then follows the finger until it reaches view2. I created a LineView class that extends view, but I don't how to proceed. I read some tutorials but none show how to do this. I think I need to get the coordinates of both view, and then create a path which "updates" on MotionEvent. I can get the coordinates and the ids of the views I want to draw a line between, but the line that I try to draw between them either goes above it, or the line does not reach past the width and height of the view. Any advice/code/clarity would be much appreciated! Here is some code: My layout. I want to draw a line between two views contained in theTableLayout.# <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/activity_game_relative_layout" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" > <TableLayout android:layout_marginTop="35dp" android:layout_marginBottom="35dp" android:id="@+id/tableLayout1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerInParent="true" > <TableRow android:id="@+id/table_row_1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:padding="5dip" > <com.example.view.DotView android:id="@+id/game_dot_1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginBottom="10dp" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:layout_marginTop="10dp" /> <com.example.view.DotView android:id="@+id/game_dot_2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginBottom="10dp" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:layout_marginTop="10dp" /> <com.example.view.DotView android:id="@+id/game_dot_3" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginBottom="10dp" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:layout_marginTop="10dp" /> </TableRow> <TableRow android:id="@+id/table_row_2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:padding="5dip" > <com.example.view.DotView android:id="@+id/game_dot_7" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginBottom="10dp" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:layout_marginTop="10dp" /> <com.example.view.DotView android:id="@+id/game_dot_8" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginBottom="10dp" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:layout_marginTop="10dp" /> <com.example.dotte.DotView android:id="@+id/game_dot_9" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginBottom="10dp" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:layout_marginTop="10dp" /> </TableRow> </TableLayout> </RelativeLayout> This is my LineView class. I use this to try and draw the actual line between the points. public class LineView extends View { Paint paint = new Paint(); float startingX, startingY, endingX, endingY; public LineView(Context context) { super(context); // TODO Auto-generated constructor stub paint.setColor(Color.BLACK); paint.setStrokeWidth(10); } public void setPoints(float startX, float startY, float endX, float endY) { startingX = startX; startingY = startY; endingX = endX; endingY = endY; invalidate(); } @Override public void onDraw(Canvas canvas) { canvas.drawLine(startingX, startingY, endingX, endingY, paint); } } And this is my Activity. public class Game extends Activity { DotView dv1, dv2, dv3, dv4, dv5, dv6, dv7; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_game); getWindow().getDecorView().setSystemUiVisibility( View.SYSTEM_UI_FLAG_LOW_PROFILE); findDotIds(); RelativeLayout rl = (RelativeLayout) findViewById(R.id.activity_game_relative_layout); LineView lv = new LineView(this); lv.setPoints(dv1.getLeft(), dv1.getTop(), dv7.getLeft(), dv7.getTop()); rl.addView(lv); // TODO: Get the coordinates of all the dots in the TableLayout. Use view tree observer. } private void findDotIds() { // TODO Auto-generated method stub dv1 = (DotView) findViewById(R.id.game_dot_1); dv2 = (DotView) findViewById(R.id.game_dot_2); dv3 = (DotView) findViewById(R.id.game_dot_3); dv4 = (DotView) findViewById(R.id.game_dot_4); dv5 = (DotView) findViewById(R.id.game_dot_5); dv6 = (DotView) findViewById(R.id.game_dot_6); dv7 = (DotView) findViewById(R.id.game_dot_7); } } The views I want to draw lines between are in the TableLayout.

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• .NET: How do I know if I have an unmanaged resource?

  - by Shiftbit

  I've read that unmanaged resource are considered file handles, streams, anything low level. Does MSDN or any other source explain how to recognize an unmanaged resource? I can't seem to find any examples on the net that show unmanaged code, all the examples just have comments that say unmanaged code here. Can someone perhaps provide a realworld example where I would handle an unmanaged resources in an IDispose interface? I provided the IDisposable interface for your convience. How do I identify an unmanaged resource? Thanks in advance! IDisposable Reference Public Class Sample : Implements IDisposable Private disposedValue As Boolean = False 'To detect redundant calls ' IDisposable Protected Overridable Sub Dispose(ByVal disposing As Boolean) If Not Me.disposedValue Then If disposing Then ' TODO: free other state (managed objects). End If ' TODO: free your own state (unmanaged objects). ' TODO: set large fields to null. End If Me.disposedValue = True End Sub ' This code added by Visual Basic to correctly implement the disposable pattern. Public Sub Dispose() Implements IDisposable.Dispose ' Do not change this code. Put cleanup code in Dispose(ByVal disposing As Boolean) above. Dispose(True) GC.SuppressFinalize(Me) End Sub End Class

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• jquery newbie: combine validate with hidding submit button.

  - by Jeffb

  I'm new a jQuery. I have gotten validate to work with my form (MVC 1.0 / C#) with this: <script type="text/javascript"> if (document.forms.length > 0) { document.forms[0].id = "PageForm"; document.forms[0].name = "PageForm"; } $(document).ready(function() { $("#PageForm").validate({ rules: { SigP: { required: true } }, messages: { SigP: "<font color='red'><b>A Sig Value is required. </b></font>" } }); }); </script> I also want to hide the Submit button to prevent twitchy mouse syndrome from causing duplicate entry before the controller completes and redirects (I'm using an GPR pattern). The following works for this purpose: <script type="text/javascript"> // // prevent double-click on submit // jQuery('input[type=submit]').click(function() { if (jQuery.data(this, 'clicked')) { return false; } else { jQuery.data(this, 'clicked', true); return true; } }); </script> However, I can't get the two to work together. Specifically, if validate fails after the Submit button is clicked (which happens given how the form works), then I can't get the form submitted again unless I do a browser refresh that resets the 'clicked' property. How can I rewrite the second method above to not set the clicked property unless the form validates? Thx.

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• Optimized Publish/Subcribe JMS Broker Cluster and Conflicting Posts on StackOverFlow for the Answer

  - by Gene

  Hi, I am looking to build a publish/subscribe distributed messaging framework that can manage huge volumes of message traffic with some intelligence at the broker level. I don't know if there's a topology that describes this, but this is the model I'm going after: EXAMPLE MODEL A A) There are two running message brokers (ideally all on localhost if possible, for easier demo-ing) : Broker-A Broker-B B) Each broker will have 2 listeners and 1 publisher. Example Figure [subscriber A1, subscriber A2, publisher A1] <-- BrokerA <-- BrokerB <-- [publisher B1, subscriber B1, subscriber B2] IF a message-X is published to broker A and there no subscribers for it among the listeners on Broker-B (via criteria in Message Selectors or Broker routing rules), then that message-X will never be published to Broker-B. ELSE, broker A will publish the message to broker B, where one of the broker B listeners/subscribers/services is expecting that message based on the subscription criteria. Is Clustering the Correct Approach? At first, I concluded that the "Broker Clustering" concept is what I needed to support this. However, as I have come to understand it, the typical use of clustering entails either: message redundancy across all brokers ... or Competing Consumers pattern ... and neither of these satisfy the requirement in the EXAMPLE MODEL A. What is the Correct Approach? My question is, does anyone know of a JMS implementation that supports the model I described? I scanned through all the stackoverflow post titles for the search: JMS and Cluster. I found these two informative, but seemingly conflicting posts: Says the EXAMPLE MODEL A is/should-be implicitly supported: http://stackoverflow.com/questions/2255816/jms-consumer-with-activemq-network-of-brokers " this means you pick a broker, connect to it, and let the broker network sort it out amongst themselves. In theory." Says the EXAMPLE MODEL A IS NOT suported: http://stackoverflow.com/questions/2017520/how-does-a-jms-topic-subscriber-in-a-clustered-application-server-recieve-message "All the instances of PropertiesSubscriber running on different app servers WILL get that message." Any suggestions would be greatly appreciated. Thanks very much for reading my post, Gene

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• NSKeyedArchiver on NSArray has large size overhead

  - by redguy

  I'm using NSKeyedArchiver in Mac OS X program which generates data for iPhone application. I found out that by default, resulting archives are much bigger than I expected. Example: NSMutableArray * ar = [NSMutableArray arrayWithCapacity:10]; for (int i = 0; i < 100000; i++) { NSString * s = [NSString stringWithFormat:@"item%06d", i]; [ar addObject:s]; } [NSKeyedArchiver archiveRootObject:ar toFile: @"NSKeyedArchiver.test"]; This stores 10 * 100000 = 1M bytes of useful data, yet the size of the resulting file is almost three megabytes. The overhead seems to be growing with number of items in the array. In this case, for 1000 items, the file was about 22k. "file" reports that it is a "Apple binary property list" (not the XML format). Is there an simple way to prevent this huge overhead? I wanted to use the NSKeyedArchiver for the simplicity it provides. I can write data to my own, non-generic, binary format, but that's not very elegant. Also, aggregating the data into large chunks and feeding these to the NSKeyedArchiver should work, but again, that kinda beats the point of using simple&easy&ready to use archiver. Am I missing some method call or usage pattern that would reduce this overhead?

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• VMWare steals IP addresses [closed]

  - by Ishan Amin

  I'm having a peculiar problem, that I think I have narrowed down to VMware. For the past one year, every once in a while we lose internet connection and not all users (about 10 users) go down at the same time, its usually one-by-one. First someone will call me and say "Internet is down" and then we would go reset the router and modem and switch and it would be working again for a while, then go down again without any pattern or replicatable sequence. We'd go repeat the steps again to get everyone in the office running again. We called our Internet Service Provider and they constantly say, We see your modem and we see your router and from thier end everything is OK. we replaced our router and switch and modem, twice! Last friday, it dawned upon me, that everytime we turn on a VMware machine, this sequence of taking everyone down starts, which also explains the message that my users get for "IP Conflict Found" So we do alot of VMware testing and lo and behold, it takes my Internet down. My Yahoo and Gtalk would continue working but www is down when the VMware machines are started. I do use bridged networking to all the VMware machines, but I dont know what else to set it at. now, sorry for this long rambling but anyone have any clue on how to stop this? thanks IA

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• Which of these is pythonic? and Pythonic vs. Speed

  - by Kashyap Nadig

  Hi! I'm new to python and just wrote this module level function: def _interval(patt): """ Converts a string pattern of the form '1y 42d 14h56m' to a timedelta object. y - years (365 days), M - months (30 days), w - weeks, d - days, h - hours, m - minutes, s - seconds""" m = _re.findall(r'([+-]?\d*(?:\.\d+)?)([yMwdhms])', patt) args = {'weeks': 0.0, 'days': 0.0, 'hours': 0.0, 'minutes': 0.0, 'seconds': 0.0} for (n,q) in m: if q=='y': args['days'] += float(n)*365 elif q=='M': args['days'] += float(n)*30 elif q=='w': args['weeks'] += float(n) elif q=='d': args['days'] += float(n) elif q=='h': args['hours'] += float(n) elif q=='m': args['minutes'] += float(n) elif q=='s': args['seconds'] += float(n) return _dt.timedelta(**args) My issue is with the for loop here i.e the long if elif block, and was wondering if there is a more pythonic way of doing it. So I re-wrote the function as: def _interval2(patt): m = _re.findall(r'([+-]?\d*(?:\.\d+)?)([yMwdhms])', patt) args = {'weeks': 0.0, 'days': 0.0, 'hours': 0.0, 'minutes': 0.0, 'seconds': 0.0} argsmap = {'y': ('days', lambda x: float(x)*365), 'M': ('days', lambda x: float(x)*30), 'w': ('weeks', lambda x: float(x)), 'd': ('days', lambda x: float(x)), 'h': ('hours', lambda x: float(x)), 'm': ('minutes', lambda x: float(x)), 's': ('seconds', lambda x: float(x))} for (n,q) in m: args[argsmap[q][0]] += argsmap[q][1](n) return _dt.timedelta(**args) I tested the execution times of both the codes using timeit module and found that the second one took about 5-6 seconds longer (for the default number of repeats). So my question is: 1. Which code is considered more pythonic? 2. Is there still a more pythonic was of writing this function? 3. What about the trade-offs between pythonicity and other aspects (like speed in this case) of programming? p.s. I kinda have an OCD for elegant code. EDITED _interval2 after seeing this answer: argsmap = {'y': ('days', 365), 'M': ('days', 30), 'w': ('weeks', 1), 'd': ('days', 1), 'h': ('hours', 1), 'm': ('minutes', 1), 's': ('seconds', 1)} for (n,q) in m: args[argsmap[q][0]] += float(n)*argsmap[q][1]

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• Core Data NSPredicate to filter results

  - by Bryan

  I have a NSManagedObject that contains a bID and a pID. Within the set of NSManagedObjects, I only want a subset returned and I'm struggling to find the correct NSPredicate or way to get what I need out of Core Data. Here's my full list: bid pid 41 0 42 41 43 0 44 0 47 41 48 0 49 0 50 43 There is a parent-child relationship above. Rules: If a record's PID = 0, it means that that record IS a parent record. If a record's PID != 0, then that record's PID refers to it's parent record's BID. Example: 1) BID = 41 is a parent record. Why? Because records BID=42 and record BID=47 have PID's of 41, meaning those are children of its PID record. 2) BID = 42 has a parent record with a BID = 41. 3) BID = 43 is a parent record. 4) BID = 44 is a parent record. 5) BID = 47 has a parent record with a BID = 41 because its PID = 41. See #1 above. 6) BID = 48 is a parent record. 7) BID = 49 is a parent record. 8) BID = 50 is a child record, and its parent record has a BID = 43. See the pattern? Now, basically from that, I want only the following rows fetched: bid pid 44 0 47 41 48 0 49 0 50 43 BID = 41, BID = 48, BID = 49 should all be returned because there are no records with a PID equal to their BID. BID = 47 should be returned because it is the most recent child of PID = 41. BID = 50 should be returned because it is the most recent child of PID = 43. Hope this helps explain it more.

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• Autodetect Presence of CSV Headers in a File

  - by banzaimonkey

  Short question: How do I automatically detect whether a CSV file has headers in the first row? Details: I've written a small CSV parsing engine that places the data into an object that I can access as (approximately) an in-memory database. The original code was written to parse third-party CSV with a predictable format, but I'd like to be able to use this code more generally. I'm trying to figure out a reliable way to automatically detect the presence of CSV headers, so the script can decide whether to use the first row of the CSV file as keys / column names or start parsing data immediately. Since all I need is a boolean test, I could easily specify an argument after inspecting the CSV file myself, but I'd rather not have to (go go automation). I imagine I'd have to parse the first 3 to ? rows of the CSV file and look for a pattern of some sort to compare against the headers. I'm having nightmares of three particularly bad cases in which: The headers include numeric data for some reason The first few rows (or large portions of the CSV) are null There headers and data look too similar to tell them apart If I can get a "best guess" and have the parser fail with an error or spit out a warning if it can't decide, that's OK. If this is something that's going to be tremendously expensive in terms of time or computation (and take more time than it's supposed to save me) I'll happily scrap the idea and go back to working on "important things". I'm working with PHP, but this strikes me as more of an algorithmic / computational question than something that's implementation-specific. If there's a simple algorithm I can use, great. If you can point me to some relevant theory / discussion, that'd be great, too. If there's a giant library that does natural language processing or 300 different kinds of parsing, I'm not interested.

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• Asynchronous background processes in Python?

  - by Geuis

  I have been using this as a reference, but not able to accomplish exactly what I need: http://stackoverflow.com/questions/89228/how-to-call-external-command-in-python/92395#92395 I also was reading this: http://www.python.org/dev/peps/pep-3145/ For our project, we have 5 svn checkouts that need to update before we can deploy our application. In my dev environment, where speedy deployments are a bit more important for productivity than a production deployment, I have been working on speeding up the process. I have a bash script that has been working decently but has some limitations. I fire up multiple 'svn updates' with the following bash command: (svn update /repo1) & (svn update /repo2) & (svn update /repo3) & These all run in parallel and it works pretty well. I also use this pattern in the rest of the build script for firing off each ant build, then moving the wars to Tomcat. However, I have no control over stopping deployment if one of the updates or a build fails. I'm re-writing my bash script with Python so I have more control over branches and the deployment process. I am using subprocess.call() to fire off the 'svn update /repo' commands, but each one is acting sequentially. I try '(svn update /repo) &' and those all fire off, but the result code returns immediately. So I have no way to determine if a particular command fails or not in the asynchronous mode. import subprocess subprocess.call( 'svn update /repo1', shell=True ) subprocess.call( 'svn update /repo2', shell=True ) subprocess.call( 'svn update /repo3', shell=True ) I'd love to find a way to have Python fire off each Unix command, and if any of the calls fails at any time the entire script stops.

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• Connecting repeatable and non-repeatble backgrounds without a seam

  - by Stiggler

  I have a 700x300 background repeating seamlessly inside of the main content-div. Now I'd like to attach a div at the bottom of the content-div, containing a different background image that isn't repeatable, connecting seamlessly with the repeatable background above it. Essentially, the non-repeatable image will look like the end piece of the repeatable image. Due to the nature of the pattern, unless the full 300px height of the background image is visible in the last repeat of the content-div's backround, the background in the div below won't seamlessly connect. Basically, I need the content div's height to be a multiple of 300px under all circumstances. What's a good approach to this sort of problem? I've tried resizing the content-div on loading the page, but this only works as long as the content div doesn't contain any resizing, dynamic content, which is not my case: function adjustContentHeight() { // Setting content div's height to nearest upper multiple of column backgrounds height, // forcing it not to be cut-off when repeated. var contentBgHeight = 300; var contentHeight = $("#content").height(); var adjustedHeight = Math.ceil(contentHeight / contentBgHeight); $("#content").height(adjustedHeight * contentBgHeight); } $(document).ready(adjustContentHeight); What I'm looking for there is a way to respond to a div resizing event, but there doesn't seem to be such a thing. Also, please assume I have no access to the JS controlling the resizing of content in the content-div, though this is potentially a way of solving the problem. Another potential solution I was thinking off was to offset the background image in the bottom div by a certain amount depending on the height of the content-div. Again, the missing piece seems to be the ability to respond to a resize event.

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• Using singleton instead of a global static instance

  - by Farstucker

  I ran into a problem today and a friend recommended I use a global static instance or more elegantly a singleton pattern. I spent a few hours reading about singletons but a few things still escape me. Background: What Im trying to accomplish is creating an instance of an API and use this one instance in all my classes (as opposed to making a new connection, etc). There seems to be about 100 ways of creating a singleton but with some help from yoda I found some thread safe examples. ..so given the following code: public sealed class Singleton { public static Singleton Instance { get; private set; } private Singleton() { APIClass api = new APIClass(); //Can this be done? } static Singleton() { Instance = new Singleton(); } } How/Where would you instantiate the this new class and how should it be called from a separate class? EDIT: I realize the Singleton class can be called with something like Singleton obj1 = Singleton.Instance(); but would I be able to access the methods within the APIs Class (ie. obj1.Start)? (not that I need to, just asking) EDIT #2: I might have been a bit premature in checking the answer but I do have one small thing that is still causing me problems. The API is launching just fine, unfortunately Im able to launch two instances? New Code public sealed class SingletonAPI { public static SingletonAPI Instance { get; private set; } private SingletonAPI() {} static SingletonAPI() { Instance = new SingletonAPI(); } // API method: public void Start() { API myAPI = new API();} } but if I try to do something like this... SingletonAPI api = SingletonAPI.Instance; api.Start(); SingletonAPI api2 = SingletonAPI.Instance; // This was just for testing. api2.Start(); I get an error saying that I cannot start more than one instance.

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• How can I effectively test against the Windows API?

  - by Billy ONeal

  I'm still having issues justifying TDD to myself. As I have mentioned in other questions, 90% of the code I write does absolutely nothing but Call some Windows API functions and Print out the data returned from said functions. The time spent coming up with the fake data that the code needs to process under TDD is incredible -- I literally spend 5 times as much time coming up with the example data as I would spend just writing application code. Part of this problem is that often I'm programming against APIs with which I have little experience, which forces me to write small applications that show me how the real API behaves so that I can write effective fakes/mocks on top of that API. Writing implementation first is the opposite of TDD, but in this case it is unavoidable: I do not know how the real API behaves, so how on earth am I going to be able to create a fake implementation of the API without playing with it? I have read several books on the subject, including Kent Beck's Test Driven Development, By Example, and Michael Feathers' Working Effectively with Legacy Code, which seem to be gospel for TDD fanatics. Feathers' book comes close in the way it describes breaking out dependencies, but even then, the examples provided have one thing in common: The program under test obtains input from other parts of the program under test. My programs do not follow that pattern. Instead, the only input to the program itself is the system upon which it runs. How can one effectively employ TDD on such a project?

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• How can I stop an auto-generated Linq to SQL class from loading ALL data?

  - by Gary McGill

  DUPLICATE of http://stackoverflow.com/questions/2433422/how-can-i-stop-an-auto-generated-linq-to-sql-class-from-loading-all-data post answers there! I have an ASP.NET MVC project, much like the NerdDinner tutorial example. (I'm using MVC 2, but followed the NerdDinner tutorial in order to create it). As per the instructions in part 3 of the tutorial, I've created a Linq-to-SQL model of my database by creating a "Linq to SQL Classes" (.dbml) surface, and dropping my database tables onto it. The designer has automatically added relationships between the generated classes based on my database tables. Let's say that my classes are as per the NerdDinner example, so I have Dinner and RSVP tables, where each Dinner record is associated with many RSVP records - hence in the generated classes, the Dinner object has a RSVPs property which is a list of RSVP objects. My problem is this: it appears (and I'd be gladly proved wrong on this) that as soon as I access a Dinner object, it's loading all of the corresponding RSVP objects, even if I don't use the RSVPs member. First question: is this really the default behavior for the generated classes? In my particular situation, the object graph contains many more tables (which have an order of magnitude more records), and so this is disastrous behaviour - I'd be loading tons of data when all I want to do is show the details of a single parent record. Second question: are there any properties exposed through the designer UI that would let me modify this behavior? (I can't find any). Third question: I've seen a description of how to control the loading of related records in a DataContext by using a DataShape object associated with the DataContext. Is that what I'm meant to do, and if so are there any tutorials like the NerdDinner one that would show not only how to do it, but also suggest a 'pattern' for normal use?

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• How can I stop an auto-generated Linq to SQL class from loading ALL data?

  - by Gary McGill

  I have an ASP.NET MVC project, much like the NerdDinner tutorial example. (I'm using MVC 2, but followed the NerdDinner tutorial in order to create it). As per the instructions in part 3 of the tutorial, I've created a Linq-to-SQL model of my database by creating a "Linq to SQL Classes" (.dbml) surface, and dropping my database tables onto it. The designer has automatically added relationships between the generated classes based on my database tables. Let's say that my classes are as per the NerdDinner example, so I have Dinner and RSVP tables, where each Dinner record is associated with many RSVP records - hence in the generated classes, the Dinner object has a RSVPs property which is a list of RSVP objects. My problem is this: it appears (and I'd be gladly proved wrong on this) that as soon as I access a Dinner object, it's loading all of the corresponding RSVP objects, even if I don't use the RSVPs member. First question: is this really the default behavior for the generated classes? In my particular situation, the object graph contains many more tables (which have an order of magnitude more records), and so this is disastrous behaviour - I'd be loading tons of data when all I want to do is show the details of a single parent record. Second question: are there any properties exposed through the designer UI that would let me modify this behavior? (I can't find any). Third question: I've seen a description of how to control the loading of related records in a DataContext by using a DataShape object associated with the DataContext. Is that what I'm meant to do, and if so are there any tutorials like the NerdDinner one that would show not only how to do it, but also suggest a 'pattern' for normal use?

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• Validation in n-tier asp.net mvc applications

  - by sTodorov

  Dear Stack Overflow gurus, I am looking for some practical/theoretical information regarding best practices for validation in asp.net mvc n-tier applications. I am working on a .Net application divided into the following layers: UI - Mvc3 BLL layer - all business rules. Decoupled from data access and UI layers through interfaces DAL layer - Data access with the repository pattern, EF4 and pocos Now, I am looking for a nice, clean and transparent way to specify my validation rules. Here are some thoughts on the matter so far: UI validation should only be responsible for user input and its validity. BLL validation should be handling the validity of the data regarding the application business rules. My main concern is how to bind the BLL and UI validation in the most efficient way. One think I am would like to avoid is having the UI check in a collection of validation and adding manually errors to the ModelState. Furthermore, I do not want to pass the ModelState to the BLL to be populated in there. I will appreciate any thoughts on the matter. P.S. Should this question be marked as a discussion ?

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