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• Data sharing amongst JPA Entities

  - by Nick

  Setup: I have a simple web app that has a handfull of forms, each on a separate page. These forms represent patient data. There is a one-to-one relationship between patient and all these forms/entities. Each form maps directly to a db table and a JPA entity, maybe not the best architecture but it works and is simple. Question: If form/entity A and form/entity B share a common chunk of data (one of more fields), what is the best way to handle that in JPA. I.E. - If the data gets inserted via form A, I need it to show up in form B as existing data and vice versa. In other words its logical for both entities to contain that data. I believe I will have to move the common data into its own entity and define the relationships that way, but I have tried many different ways and none gets me all the way, at least with basic JPA. Can this be done through pure JPA relationships or will I have to write a bunch of code to make this happen manually. Not looking for code specifically, just the correct way to model this data. Thanks.

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• VB.NET invalid cast exception

  - by user127147

  Hi there, I have a simple application to store address details and edit them. I have been away from VB for a few years now and need to refreash my knowledge while working to a tight deadline. I have a general Sub responsible for displaying a form where user can add contact details (by pressing button add) and edit them (by pressing button edit). This sub is stored in a class Contact. The way it is supposed to work is that there is a list with all the contacts and when new contact is added a new entry is displayed. If user wants to edit given entry he or she selects it and presses edit button Public Sub Display() Dim C As New Contact C.Cont = InputBox("Enter a title for this contact.") C.Fname = frmAddCont.txtFName.Text C.Surname = frmAddCont.txtSName.Text C.Address = frmAddCont.txtAddress.Text frmStart.lstContact.Items.Add(C.Cont.ToString) End Sub I call it from the form responsible for adding new contacts by Dim C As New Contact C.Display() and it works just fine. However when I try to do something similar using the edit button I get errors - "Unable to cast object of type 'System.String' to type 'AddressBook.Contact'." Dim C As Contact If lstContact.SelectedItem IsNot Nothing Then C = lstContact.SelectedItem() C.Display() End If I think it may be something simple however I wasn't able to fix it and given short time I have I decided to ask for help here. Thank you

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• Entity Framework lazy loading doesn't work from other thread

  - by Thomas Levesque

  Hi, I just found out that lazy loading in Entity Framework only works from the thread that created the ObjectContext. To illustrate the problem, I did a simple test, with a simple model containing just 2 entities : Person and Address. Here's the code : private static void TestSingleThread() { using (var context = new TestDBContext()) { foreach (var p in context.Person) { Console.WriteLine("{0} lives in {1}.", p.Name, p.Address.City); } } } private static void TestMultiThread() { using (var context = new TestDBContext()) { foreach (var p in context.Person) { Person p2 = p; // to avoid capturing the loop variable ThreadPool.QueueUserWorkItem( arg => { Console.WriteLine("{0} lives in {1}.", p2.Name, p2.Address.City); }); } } } The TestSingleThread method works fine, the Address property is lazily loaded. But in TestMultiThread, I get a NullReferenceException on p2.Address.City, because p2.Address is null. It that a bug ? Is this the way it's supposed to work ? If so, is there any documentation mentioning it ? I couldn't find anything on the subject on MSDN or Google... And more importantly, is there a workaround ? (other than explicitly calling LoadProperty from the worker thread...) Any help would be very appreciated PS: I'm using VS2010, so it's EF 4.0. I don't know if it was the same in the previous version of EF...

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• F# Class with Generics : 'constructor deprecated' error

  - by akaphenom

  I am trying to create a a class that will store a time series of data - organized by groups, but I had some compile errors so I stripped down to the basics (just a simple instantiation) and still can't overcome the compile error. I was hoping some one may have seen this issue before. Clas is defined as: type TimeSeriesQueue<'V, 'K when 'K: comparison> = class val private m_daysInCache: int val private m_cache: Map<'K, 'V list ref > ref; val private m_getKey: ('V -> 'K) ; private new(getKey) = { m_cache = ref Map.empty m_daysInCache = 7 ; m_getKey = getKey ; } end So that looks OK to me (it may not be, but doesnt have any errors or warnings) - the instantiation gets the error: type tempRec = { someKey: string ; someVal1: int ; someVal2: int ; } let keyFunc r:tempRec = r.someKey // error occurs on the following line let q = new TimeSeriesQueue<tempRec, string> keyFunc This construct is deprecated: The use of the type syntax 'int C' and 'C ' is not permitted here. Consider adjusting this type to be written in the form 'C' NOTE This may be simple stupidity - I am just getting back from holiday and my brain is still on time zone lag...

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• Looped jQuery slideshow with smooth cross-fades

  - by artlung

  I'm trying to do a simple rotating image on the home page. Under the hood I'm reading a directory and then populating urls for the images into an array. What I want to do is cross-fade the images. If it was just a matter of showing the next one, it's easy, but since I need to cross-fade, it's a bit harder. I think what I want to do is do the fades by calling animate() on the opacity value of the <img> tag, and in between swapping out the css background-image property of the enclosing <div>. But the results are not that great. I've used tools for more full featured slideshows, but I don't want the overhead of adding a plugin if I can avoid it, and a simple crossfade seems like it should be easier. Here's my JavaScript (I'm using jQuery 1.3.2): var slideshow_images = ["http:\/\/example.com\/wordpress\/wp-content\/themes\/testtheme\/sidebar-home-bg\/bg1.jpg","http:\/\/example.com\/wordpress\/wp-content\/themes\/testtheme\/sidebar-home-bg\/bg2.jpg","http:\/\/example.com\/wordpress\/wp-content\/themes\/testtheme\/sidebar-home-bg\/bg3.jpg"]; var slideshow_index = 0; var delay = 4000; var swapSlides = function() { var slideshow_count = slideshow_images.length; // initialize the background to be the current image $('#home-slideshow').css({ 'background-image': 'url(' + slideshow_images[slideshow_index] + ')', 'background-repeat:': 'no-repeat', 'width': 200, 'overflow': 'hidden' }); slideshow_index = ((slideshow_index + 1) == slideshow_count) ? 0 : slideshow_index + 1; // fade out the img $('#home-slideshow img').animate({opacity: 0}, delay); // now, the background is visible // next change the url on the img $('#home-slideshow img').attr('src', slideshow_images[slideshow_index]); // and fade it up $('#home-slideshow img').animate({opacity: 1.0}, delay); // do it again setTimeout('swapSlides()', 4000); } jQuery(document).ready(function(){ if (swapSlides) { swapSlides(); } }); And here's the markup I'm using: <div id="home-slideshow"><img src="http://example.com/wordpress/wp-content/themes/testtheme/sidebar-home-bg/bg1.jpg" alt="" /></div>

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• Why so much stack space used for each recursion?

  - by Harvey

  I have a simple recursive function RCompare() that calls a more complex function Compare() which returns before the recursive call. Each recursion level uses 248 bytes of stack space which seems like way more than it should. Here is the recursive function: void CMList::RCompare(MP n1) // RECURSIVE and Looping compare function { auto MP ne=n1->mf; while(StkAvl() && Compare(n1=ne->mb)) RCompare(n1); // Recursive call ! } StkAvl() is a simple stack space check function that compares the address of an auto variable to the value of an address near the end of the stack stored in a static variable. It seems to me that the only things added to the stack in each recursion are two pointer variables (MP is a pointer to a structure) and the stuff that one function call stores, a few saved registers, base pointer, return address, etc., all 32-bit (4 byte) values. There's no way that is 248 bytes is it? I don't no how to actually look at the stack in a meaningful way in Visual Studio 2008. Thanks

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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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• django shopping cart as a beginner

  - by Jacques Knie

  Hi, i'm quite new to django and trying to add a shopping cart to a simple webshop. What I need is a simple cart that can be filled and presents its content, which is then sent to the vendor via email. So Satchmo might be too big for this task. Therefore i chose django-cart (http://code.google.com/p/django-cart/) which causes some problems now. 1. Is django-cart the right thing? Or are there any better approaches to this task? 2. As I am a beginner even django-cart makes me struggle. I used the view and the template of the django-cart-website, but writing a form that can be used to add products to the cart took me hours. I probably need help in understanding the general layout of a shopping cart and its integration into a website. 3. Two more specific questions: Is it possible to dynamically populate a formfield in a template (e.g. with {{ object.id }})? Is django-cart able to change (update) the contents of a cart? I hope it's not too many questions at once. Thanks in advance Jacques

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• Non RBAC User Roles and Permissions System: checking the user's City

  - by micha12

  We are currently designing a User Roles and Permissions System in our web application (ASP.NET), and it seems that we have several cases that do no fit within the classical Role-Based Access Control (RBAC). I will post several questions, each devoted to a particular case, this being the first post. We have the following case: not to allow a user view a certain page if the user lives in a particular city. This is a simple case that is coded in the following way: if (User.City == “Moscow”) // Allow the user to view the page. else // Do not allow the user to view this page. Though this case is very simple and straightforward, it has nothing to do with the RBAC. On StackOverflow, someone called this an Attribute-based Access Control. Under the classical RBAC, it seems that this case should be designed like this: introduce a permission “City where the person lives”, this permission will have a property City. Then create a role, add a permission of type “City = Moscow” to it and the assign the role to the user. Looks extremely cumbersome. The question is whether it is acceptable to introduce such non-RBAC approaches to our permissions system – does that break the design or not? This might seem a primitive question, but we found that most applications use pure RBAC, and we started to think that we might be doing something wrong. Thank you.

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• Django Models / SQLAlchemy are bloated! Any truly Pythonic DB models out there?

  - by Luke Stanley

  "Make things as simple as possible, but no simpler." Can we find the solution/s that fix the Python database world? from someAmazingDB import * class Task (model): title = '' isDone = False db.taskList = [] #or db.taskList = expandableTypeCollection(Task) #not sure what this syntax would be db['taskList'].append(Task(title='Beat old sql interfaces',done=False)) db.taskList.append(Task('Illustrate different syntax modes',True)) #at this point it should autosave #we should be able to reload the console and access like: >> from someAmazingDB import * >> print 'Done tasks:' >> for task in db.taskList: >> if task.done: >> print task 'Illustrate different syntax modes' I'm a fan of Python, webPy and Cherry Py, and KISS in general. We're talking automatic Python to SQL type translation or NoSQL. We don't have to totally be SQL compatible! Just a scalable subset or ignore it! Re:model changes, it's ok to ask the developer when they try to change it or have a set of sensible defaults. Here is the challenge: The above code should work with very little modification or thinking required. Why must we put up with compromise when we know better? It's 2010, we should be able to code scalable, simple databases in our sleep. If you think this is important, please upvote!

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• Beginner question about CSS and layout and height

  - by vtortola

  Hi, I'm trying to create a very simple page that contains a container, a header, a left column and a footer: [containter] [header /] [content /] [leftBar /] [footer /] [/containter] (Sorry, I cannot paste the code properly, only appears the tag "body" and the rest disapears :S ... ) As you can see, very simple stuff. I want to use the 100% of the height, as I can do with the width, but I simply don`t get it work :S At his moment I'm using min-height, but how could I use the height:100% ? What I like is that the footer is always visible, and you scroll the content. This is what I have till the moment: body { font-family: Verdana; font-size: 0.8em; background-color:#f1f1f1; } container { border:solid 2px Black; position:absolute; left:10%; width:80%; margin:auto; } header { height:20px; background: #DDDDDD; } leftBar { width: 20%; background: #669966; min-height:600px; postion:absolute; top:20px; bottom:20px; } content { float:right; background-color: #cdcde6; position:absolute; left:20%; right:0px; bottom:20px; top:20px; padding:5px; } footer { position:absolute; height:20px; } I'm reading a book about CSS, but I still don't get the part about the height :S Thanks in advance.

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• WPF - How to properly reference a class from XAML

  - by Andy T

  OK, this is a super super noob question, one that I'm almost embarrassed to ask... I want to reference a class in my XAML file. It's a DataTemplateSelector for selecting the right edit template for a DataGrid column. Anyway, I've written the class into my code behind, added the local namespace to the top of top of the XAML, but when I try to reference the class from the XAML, it tells me the class does not exist in the local namespace. I must be missing something really really simple but I just can't understand it... Here's my code. XAML: <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:tk="http://schemas.microsoft.com/wpf/2008/toolkit" xmlns:local="clr-namespace:CustomFields" xmlns:col="clr-namespace:System.Collections;assembly=mscorlib" xmlns:sys="clr-namespace:System;assembly=mscorlib" x:Class="CustomFields.MainWindow" x:Name="Window" Title="Define Custom Fields" Width="425" Height="400" MinWidth="425" MinHeight="400"> <Window.Resources> <ResourceDictionary> <local:RangeValuesEditTemplateSelector> blah blah blah... </local:RangeValuesEditTemplateSelector> </ResourceDictionary> </Window.Resources> C#: namespace CustomFields { /// /// Interaction logic for MainWindow.xaml /// public partial class MainWindow : Window { public MainWindow() { this.InitializeComponent(); // Insert code required on object creation below this point. } } public class RangeValuesEditTemplateSelector : DataTemplateSelector { public RangeValuesEditTemplateSelector(){ MessageBox.Show("hello"); } } } Any ideas what I'm doing wrong? I thought this should be simple as 1-2-3... Thanks! AT

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• ajax delay load UserControl asp.net

  - by user196202

  regarding ajax delay load of usercontrols (or any controls) on Post at Encosia.com : http://encosia.com/2008/02/05/boost-aspnet-performance-with-deferred-content-loading/ I tried to implement it , but I noticed that it can be done only for simple controls or UserControls that Have simple asp.net controls (or html tags) . But when it involved with advanced dynamic ajax control (like ajaxControlToolkit or Telerik controls) that have javascripts inside them This method of injecting the html code to the .InnerHtml property of div tag (for example) IS NOT WORKING , and I red about it that The browser need to load the script on load and after that it won't iterperate the scripts injectd via .InnerHtml. So I attached here example of delay load project (from encosia.com by dave ward) with my modification (look at DefaultPopup.aspx and beforePopup.aspx and AfterPopup.aspx) Which I modified the RssReader to show listview with popup items (which is implemented via ACT HoverMenuExtender ) So in the regular way the popup items are shown right , but on the delay load which is done by creating virtual page for rendering the html and injecting it to .InnerHtml property – This ISN'T WORKING. So my question is : is there a way to do delay loading for controls which include scripts lik ACT and Telerik and others? And for the ajax templates – if I need to inject advanced control to the page – how I do it with your approach? Thanks very much (I can't attach here files so everyone please ask me by mail ([email protected]) and i'll send it to him. ) Zahi Kramer

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• Stock management of assemblies and its sub parts

  - by The Disintegrator

  I have to track the stock of individual parts and kits (assemblies) and can't find a satisfactory way of doing this. Sample bogus and hyper simplified database: Table prod: prodID 1 prodName Flux capacitor prodCost 900 prodPrice 1350 (900*1.5) prodStock 3 - prodID 2 prodName Mr Fusion prodCost 300 prodPrice 600 (300*2) prodStock 2 - prodID 3 prodName Time travel kit prodCost 1650 (1350+300) prodPrice 2145 (1650*1.3) prodStock 2 Table rels relID 1 relSrc 1 (Flux capacitor) relType 4 (is a subpart of) relDst 3 (Time travel kit) - relID 2 relSrc 2 (Mr Fusion) relType 4 (is a subpart of) relDst 3 (Time travel kit) prodPrice: it's calculated based on the cost but not in a linear way. In this example for costs of 500 or less, the markup is a 200%. For costs of 500-1000 the markup is 150%. For costs of 1000+ the markup is 130% That's why the time travel kit is much cheaper than the individual parts prodStock: here is my problem. I can sell kits or the individual parts, So the stock of the kits is virtual. The problem when I buy: Some providers sell me the Time Travel kit as a whole (with one barcode) and some sells me the individual parts (with a different barcode) So when I load the stock I don't know how to impute it. The problem when I sell: If I only sell kits, calculate the stock would be easy: "I have 3 Flux capacitors and 2 Mr Fusions, so I have 2 Time travel kits and a Flux Capacitor" But I can sell Kits or individual parts. So, I have to track the stock of the individual parts and the possible kits at the same time (and I have to compensate for the sell price) Probably this is really simple, but I can't see a simple solution. Resuming: I have to find a way of tracking the stock and the database/program is the one who has to do it (I cant ask the clerk to correct the stock) I'm using php+MySql. But this is more a logical problem than a programing one

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• How do I pass an array of structs (containing std:string or BSTR) from ATL to C#. SafeArray? Varian

  - by Andrew

  Hi, I have an ATL COM object that I am using from C#. The interface currently looks like: interface ICHASCom : IDispatch{ [id(1), helpstring("method Start")] HRESULT Start([in] BSTR name, [out,retval] VARIANT_BOOL* result); ... [id(4), helpstring("method GetCount")] HRESULT GetCount([out,retval] LONG* numPorts); ... [id(7), helpstring("method EnableLogging")] HRESULT EnableLogging([in] VARIANT_BOOL enableLogging); }; That is, it's a very simple interface. I also have some events that I send back too. Now, I would like to add something to the interface. In the ATL I have some results, which are currently structs and look like struct REPORT_LINE { string creationDate; string Id; string summary; }; All the members of the struct are std::string. I have an array of these that I need to get back to the C#. What's the best way to do this? I suspect someone is going to say, "hey, you can't just send std::string over COM like that. If so, fine, but what's the best way to modidfy the struct? Change the std::string to BSTR? And then how do I, 1) Set up the IDL to pass an array of structs (structs with BSTR or std::string) 2) If I must use SAFEARRAYS, how do I fill the SAFEARRAYS with the structs. I'm not familiar with COM except for use with simple types. Thanks, Dave

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• How to serialize a Bundle?

  - by hermo

  I'd like to serialize a Bundle object, but can't seem to find a simple way of doing it. Using Parcel doesn't seem like an option, since I want to store the serialized data to file. Any ideas on ways to do this? The reason I want this is to save and restore the state of my activity, also when it's killed by the user. I already create a Bundle with the state I want to save in onSaveInstanceState. But android only keeps this Bundle when the activity is killed by the SYSTEM. When the user kills the activity, I need to store it myself. Hence i'd like to serialize and store it to file. Of course, if you have any other way of accomplishing the same thing, i'd be thankful for that too. Edit: I decided to encode my state as a JSONObject instead of a Bundle. The JSON object can then be put in a Bundle as a Serializable, or stored to file. Probably not the most efficient way, but it's simple, and it seems to work ok.

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• Access and modify attributes/objects which are not part of the form backing bean

  - by spa

  I use Spring MVC (via Spring Roo) to build a small web application for administering persons. In the page for creating a person the bean Person is used as form backing object (key "person" in the model map). <form:form action="${form_url}" method="POST" modelAttribute="person"> I would like to add some attributes to the model map which can be altered by the user in the creation form. Basically, I try to add a Boolean, so that I can control which page is displayed next after the user presses the submit button. I try to modify the Boolean (key "myBoolean" in the model map) using a simple checkbox: <form:checkbox id="_myboolean_id" path="myBoolean"/> However, as I am new to Spring MVC I have some difficulties here. The Boolean object is not an attribute of the form backing object. So if I try to access it the following exception is thrown (of course): Invalid property 'myBoolean' of bean class [de.cm.model.Person]: Bean property 'myBoolean' is not readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter? Is there are way to access a value of the model map directly? The only solution I can imagine right now is a kind of wrapper object around the class Person and my additional attributes which is used as a new form backing object. However, this is more work for a IMHO simple task. Do you have a better solution?

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• Slow MySQL Query Breaking my back!

  - by Chris n

  so, I have tried everything I can think of, and can't get this query to happen in less than 3 seconds on my local server. I know the problem has to do with the OR referencing both the owner_id and the person_id. if I run one or the other it happens instantly, but together with an or I can't seem to make it work - I looked into rewriting the code, but the way the app was designed it won't be easy. is there a way I can call an equivalent or that won't take so long? here is the sql: SELECT event_types.name as event_type_name,event_types.id as id, count(events.id) as count,sum(events.estimated_duration) as time_sum FROM events,event_types WHERE event_types.id = events.event_type_id AND events.event_type_id != '4' AND ( events.status!='cancelled') AND events.event_type_id != 64 AND ( events.owner_id = 161 OR events.person_id = 161 ) GROUP BY event_types.name ORDER BY event_types.name DESC; Here's the Explain soup, although I'm guessing it's unnecessary cause there is probably a better way to structure that or that is obvious: thanks so much! chris. +----+-------------+-------------+-------+---------------------------------------------------------------------------------------------------------+-------------------------------+---------+-------------------------------------+------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------------+-------+---------------------------------------------------------------------------------------------------------+-------------------------------+-- | 1 | SIMPLE | event_types | range | PRIMARY | PRIMARY | 4 | NULL | 78 | Using where; Using temporary; Using filesort | | 1 | SIMPLE | events | ref | index_events_on_status,index_events_on_event_type_id,index_events_on_person_id,index_events_on_owner_id | index_events_on_event_type_id | 5 | thenumber_production.event_types.id | 907 | Using where | +----+-------------+-------------+-------+---------------------------------------------------------------------------------------------------------+-------------------------------+---------+-------------------------------------+------+----------------------------------------------+

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• Figuring out the Nyquist performance limitation of an ADC on an example PIC microcontroller

  - by AKE

  I'm spec-ing the suitability of a dsPIC microcontroller for an analog-to-digital application. This would be preferable to using dedicated A/D chips and a separate dedicated DSP chip. To do that, I've had to run through some computations, pulling the relevant parameters from the datasheets. I'm not sure I've got it right -- would appreciate a check! (EDITED NOTE: The PIC10F220 in the example below was selected ONLY to walk through a simple example to check that I'm interpreting Tacq, Fosc, TAD, and divisor correctly in working through this sort of Nyquist analysis. The actual chips I'm considering for the design are the dsPIC33FJ128MC804 (with 16b A/D) or dsPIC30F3014 (with 12b A/D).) A simple example: PIC10F220 is the simplest possible PIC with an ADC Runs at clock speed of 8MHz. Has an instruction cycle of 0.5us (4 clock steps per instruction) So: Taking Tacq = 6.06 us (acquisition time for ADC, assume chip temp. = 50*C) [datasheet p34] Taking Fosc = 8MHz (? clock speed) Taking divisor = 4 (4 clock steps per CPU instruction) This gives TAD = 0.5us (TAD = 1/(Fosc/divisor) ) Conversion time is 13*TAD [datasheet p31] This gives conversion time 6.5us ADC duration is then 12.56 us [? Tacq + 13*TAD] Assuming at least 2 instructions for load/store: This is another 1 us [0.5 us per instruction] Which would give max sampling rate of 73.7 ksps (1/13.56) Supposing 8 more instructions for real-time processing: This is another 4 us Thus, total ADC/handling time = 17.56us (12.56us + 1us + 4us) So expected upper sampling rate is 56.9 ksps. Nyquist frequency for this sampling rate is therefore 28 kHz. If this is right, it suggests the (theoretical) performance suitability of this chip's A/D is for signals that are bandlimited to 28 kHz. Is this a correct interpretation of the information given in the data sheet in obtaining the Nyquist performance limit? Any opinions on the noise susceptibility of ADCs in PIC / dsPIC chips would be much appreciated! AKE

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• Distutils - Where Am I going wrong?

  - by RJBrady

  I wanted to learn how to create python packages, so I visited http://docs.python.org/distutils/index.html. For this exercise I'm using Python 2.6.2 on Windows XP. I followed along with the simple example and created a small test project: person/ setup.py person/ __init__.py person.py My person.py file is simple: class Person(object): def __init__(self, name="", age=0): self.name = name self.age = age def sound_off(self): print "%s %d" % (self.name, self.age) And my setup.py file is: from distutils.core import setup setup(name='person', version='0.1', packages=['person'], ) I ran python setup.py sdist and it created MANIFEST, dist/ and build/. Next I ran python setup.py install and it installed it to my site packages directory. I run the python console and can import the person module, but I cannot import the Person class. >>>import person >>>from person import Person Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: cannot import name Person I checked the files added to site-packages and checked the sys.path in the console, they seem ok. Why can't I import the Person class. Where did I go wrong?

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• best way to pick a random subset from a collection?

  - by Tom

  I have a set of objects in a Vector from which I'd like to select a random subset (e.g. 100 items coming back; pick 5 randomly). In my first (very hasty) pass I did an extremely simple and perhaps overly clever solution: Vector itemsVector = getItems(); Collections.shuffle(itemsVector); itemsVector.setSize(5); While this has the advantage of being nice and simple, I suspect it's not going to scale very well, i.e. Collections.shuffle() must be O(n) at least. My less clever alternative is Vector itemsVector = getItems(); Random rand = new Random(System.currentTimeMillis()); // would make this static to the class List subsetList = new ArrayList(5); for (int i = 0; i < 5; i++) { // be sure to use Vector.remove() or you may get the same item twice subsetList.add(itemsVector.remove(rand.nextInt(itemsVector.size()))); } Any suggestions on better ways to draw out a random subset from a Collection?

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• Duplicate entries on mysql on insert using doctrine

  - by Nikos Galis

  Hi all! I am facing a very weird problem with mysql and doctrine [with help of codeIgniter]. I am trying to make a simple migration script taking all records from one table and after a little process, saving them to another. However, on my laptop [running windows and wamp] I get double numbers of the original table records to have been copied to the destination table. In my colleagues' laptops, everything works fine! We are all using mysql 5.0.86 [plus windows plus wamp]. Here is the code : function buggy_function(){ $this->db(); //get db connection $q = Doctrine_Query::create()->from('Oldtable r'); $oldrecords = $q->fetchArray(); $count = 0; foreach ($oldrecords as $oldrecord){ $newrecord = new NewTableClass(); $newrecord->password = md5($oldrecord['password']); $newrecord->save(); echo $newrecord->id. ' Id -> saved.' } } Simple as that! I have 39 records on the Old table and I am getting 78 records in the new table, which are exactly the same records, except from the unique primary key. It seems as if the script runs twice. But the output of the script is the following : 1 Id -> saved. 2 Id -> saved. ... ... 39 Id -> saved. Do you have any idea why this is happening? Any known bug for mysql? Thank you in advanced!'

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• What AOP tools exist for doing aspect-oriented programming at the assembly language level against x8

  - by JohnnySoftware

  Looking for a tool I can use to do aspect-oriented programming at the assembly language level. For experimentation purposes, I would like the code weaver to operate native application level executable and dynamic link libraries. I have already done object-oriented AOP. I know assembly language for x86 and so forth. I would like to be able to do logging and other sorts of things using the familiar before/after/around constructs. I would like to be able to specify certain instructions or sequences/patterns of consecutive instructions as what to do a pointcut on since assembly/machine language is not exactly the most semantically rich computer language on the planet. If debugger and linker symbols are available, naturally, I would like to be able to use them to identify subroutines' entry points , branch/call/jump target addresses, symbolic data addresses, etc. I would like the ability to send notifications out to other diagnostic tools. Thus, support for sending data through connection-oriented sockets and datagrams is highly desirable. So is normal logging to files, UI, etc. This can be done using the action part of an aspect to make a function call, but then there are portability issues so the tool needs to support a flexible, well-abstracted logging/notifying mechanism with a clean, simple yet flexible. The goal is rapid-QA. The idea is to be able to share aspect source code braodly within communties as well as publicly. So, there needs to be a declarative security policy file that users can share. This insures that nothing untoward that is hidden directly or indirectly in an aspect source file slips by the execution manager. The policy file format needs to be simple to read, write, modify, understand, type-in, edit, and generate. Sort of like Java .policy files. Think the exact opposite of anything resembling XML Schema files and you get the idea. Is there such a tool in existence already?

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• WPF TextBlock Binding to DependencyProperty

  - by Bill Campbell

  Hi, I have what I believe to be about one of the most simple cases of attempting to bind a view to a dependencyproperty in the view model. It seems that the initial changes are reflected in the view but other changes to the DP do not update the view's TextBlock. I'm probably just missing something simple but I just can't see what it is. Please take a look... My XAML has a status bar on the bottom of the window. I want to bind to the DP "VRAStatus". <StatusBar x:Name="sbar" Grid.Column="0" Grid.Row="2" Grid.ColumnSpan="2" VerticalAlignment="Bottom" Background="LightBlue" Opacity="0.4" DockPanel.Dock="Bottom" > <StatusBarItem> <TextBlock x:Name="statusBar" Text="{Binding VRAStatus}" /> </StatusBarItem> <StatusBarItem> <Separator Style="{StaticResource StatusBarSeparatorStyle}"/> </StatusBarItem> </StatusBar> My viewmodel has the DP defined: public string VRAStatus { get { return (string)GetValue(VRAStatusProperty); } set { SetValue(VRAStatusProperty, value); } } // Using a DependencyProperty as the backing store for VRAStatus. public static readonly DependencyProperty VRAStatusProperty = DependencyProperty.Register("VRAStatus", typeof(string), typeof(PenskeRouteAssistViewModel),new PropertyMetadata(string.Empty)); Then, in my code I set the DP: VRAStatus = "Test Message..."; Is there something obvious here that I am missing? In my constructor for the viewmodel I set the DP like this: VRAStatus = "Ready"; I never get the Test Message to display. Please Help. thanks in advance! Bill

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• What is the best practice for using lock within inherited classes

  - by JDMX

  I want to know if one class is inheriting from another, is it better to have the classes share a lock object that is defined at the base class or to have a lock object defined at each inheritance level. A very simple example of a lock object on each level of the class public class Foo { private object thisLock = new object(); private int ivalue; public int Value { get { lock( thisLock ) { return ivalue; } } set { lock( thisLock ) { ivalue= value; } } } } public class Foo2: Foo { private object thisLock2 = new object(); public int DoubleValue { get { lock( thisLock2 ) { return base.Value * 2; } } set { lock( thisLock2 ) { base.Value = value / 2; } } } } public class Foo6: Foo2 { private object thisLock6 = new object(); public int TripleDoubleValue { get { lock( thisLock6 ) { return base.DoubleValue * 3; } } set { lock( thisLock6 ) { base.DoubleValue = value / 3; } } } } A very simple example of a shared lock object public class Foo { protected object thisLock = new object(); private int ivalue; public int Value { get { lock( thisLock ) { return ivalue; } } set { lock( thisLock ) { ivalue= value; } } } } public class Foo2: Foo { public int DoubleValue { get { lock( thisLock ) { return base.Value * 2; } } set { lock( thisLock ) { base.Value = value / 2; } } } } public class Foo6: Foo2 { public int TripleDoubleValue { get { lock( thisLock ) { return base.DoubleValue * 3; } } set { lock( thisLock ) { base.DoubleValue = value / 3; } } } } Which example is the preferred way to manage locking within an inherited class?

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