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  • Store the cache data locally

    - by Lu Lu
    Hello, I develops a C# Winform application, it is a client and connect to web service to get data. The data returned by webservice is a DataTable. Client will display it on a DataGridView. My problem is that: Client will take more time to get all data from server (web service is not local with client). So I must to use a thread to get data. This is my model: Client create a thread to get data - thread complete and send event to client - client display data on datagridview on a form. However, when user closes the form, user can open this form in another time, and client must get data again. This solution will cause the client slowly. So, I think about a cached data: Client <---get/add/edit/delete--- Cached Data ---get/add/edit/delete---Server (web service) Please give me some suggestions. Example: cached data should be developed in another application which is same host with client? Or cached data is running in client. Please give me some techniques to implement this solution. If having any examples, please give me. Thanks.

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  • How to display configurable product in each color in product listing?

    - by Thomas
    I have a configurable product which is available in many different colors and sizes. I want the configurable product to appear once for every color. My idea is to assign one simple product of the configurable product in every color to the category of the configurable product. Then I want to change the listing, so that the (colored) simple product links to it's master product (the configurable one). The other way would be, to just assign the configurable product to a category and then list it multiple times with different colors. But I think this would be to complicated.

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  • How to handle concurrency control in dynamic data?

    - by Andrew
    I've been quite impressed with dynamic data and how easy and quick it is to get a simple site up and running. I'm planning on using it for a simple internal HR admin site for registering people's skills/degrees/etc. I've been watching the intro videos at www.asp.net/dynamicdata and one thing they never mention is how to handle concurrency control. It seems that DD does not handle it right out of the box (unless there is some setting I haven't seen) as I manually generated a change conflict exception and the app failed without any user friendly message. Anybody know if DD handles it out of the box? Or do you have to somehow build it into the site?

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  • The "correct" way to define an exception in Python without PyLint complaining

    - by Evgeny
    I'm trying to define my own (very simple) exception class in Python 2.6, but no matter how I do it I get some warning. First, the simplest way: class MyException(Exception): pass This works, but prints out a warning at runtime: DeprecationWarning: BaseException.message has been deprecated as of Python 2.6 OK, so that's not the way. I then tried: class MyException(Exception): def __init__(self, message): self.message = message This also works, but PyLint reports a warning: W0231: MyException.__init__: __init__ method from base class 'Exception' is not called. So I tried calling it: class MyException(Exception): def __init__(self, message): super(Exception, self).__init__(message) self.message = message This works, too! But now PyLint reports an error: E1003: MyException.__init__: Bad first argument 'Exception' given to super class How the hell do I do such a simple thing without any warnings?

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  • Point data structure for a sketching application

    - by bebraw
    I am currently developing a little sketching application based on HTML5 Canvas element. There is one particular problem I haven't yet managed to find a proper solution for. The idea is that the user will be able to manipulate existing stroke data (points) quite freely. This includes pushing point data around (ie. magnet tool) and manipulating it at whim otherwise (ie. altering color). Note that the current brush engine is able to shade by taking existing stroke data in count. It's a quick and dirty solution as it just iterates the points in the current stroke and checks them against a distance rule. Now the problem is how to do this in a nice manner. It is extremely important to be able to perform efficient queries that return all points within given canvas coordinate and radius. Other features, such as space usage, should be secondary to this. I don't mind doing some extra processing between strokes while the user is not painting. Any pointers are welcome. :)

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  • What is the safest way to pass strings around in C?

    - by chucknelson
    I have a program in C using Solaris with VERY ancient compatibility it seems. Many examples, even here on SO, don't work, as well as lots of code I've written on Mac OS X. So when using very strict C, what is the safest way to pass strings? I'm currently using char pointers all over the place, due to what I thought was simplicity. So I have functions that return char*, I'm passing char* to them, etc. I'm already seeing strange behavior, like a char* I passed having its value right when I enter a function, and then the value being mysteriously gone OR corrupted/overwritten after something simple like one printf() or an malloc to some other pointer. I was thinking maybe declaring a local char[] inside each function, using strcpy() immediately, and then eventually returning a pointer where char *returnval = strdup(localchar[]); This seems...sloppy. Can anyone point me in the right direction on a simple requirement?

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  • Java2D: Fill a convex rounded polygon (QuadCurves)

    - by Martijn Courteaux
    Hi, If I have a QuadCurve like this (+ = node): + + \ ./ +--?? And I fill it in Java 2D the result is something like this: (x = colored) +xxxxxxxxx+ \xxxxxx./ +--?? But I want to color the other side: + + x\ ./x xxx +--??xx xxxxxxxxxxx This succeeds by drawing a rectangle around the curve in the color I want to color the other side and then fill the curve with the background color. But this isn't good enough to fill a convex rounded (based on QuadCurves) polygon. In case of some coordinates for the rectangles (as explained in the trick I used) overlap other pieces of the polygon. Here are two images (the green area is my polygon): So, the question is simple: "How can I color a shape build of curves?" But to the answer will not be simple I think... Any advice would be VERY VERY appreciated. Thanks in advance. Maybe I'm going to make a bounty for this question if I don't get an answer

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  • Conditional operator in Mako using Pylons

    - by Antoine Leclair
    In PHP, I often use the conditional operator to add an attribute to an html element if it applies to the element in question. For example: <select name="blah"> <option value="1"<?= $blah == 1 ? ' selected="selected"' : '' ?>> One </option> <option value="2"<?= $blah == 2 ? ' selected="selected"' : '' ?>> Two </option> </select> I'm starting a project with Pylons using Mako for the templating. How can I achieve something similar? Right now, I see two possibilities that are not ideal. Solution 1: <select name="blah"> % if blah == 1: <option value="1" selected="selected">One</option> % else: <option value="1">One</option> % endif % if blah == 2: <option value="2" selected="selected">Two</option> % else: <option value="2">Two</option> % endif </select> Solution 2: <select name="blah"> <option value="1" % if blah == 1: selected="selected" % endif >One</option> <option value="2" % if blah == 2: selected="selected" % endif >Two</option> </select> In this particular case, the value is equal to the variable tested (value="1" = blah == 1), but I use the same pattern in other situations, like <?= isset($variable) ? ' value="$variable" : '' ?>. I am looking for a clean way to achieve this using Mako.

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  • MVVM Listbox DataTemplate SelectedItem

    - by StinkerPeter
    I am using a ListBox with a DataTemplate as shown below (xaml simplified and variable names changed). <ListBox ItemsSource="{Binding Path=ObservCollectionItems}" SelectedItem="{Binding Path=SelectedItemVar, Mode=TwoWay}"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel> <TextBlock Text="{Binding SomeVar}" /> <Border> <StackPanel> <Button Content="String1" Command="{Binding DataContext.Command1} RelativeSource={RelativeSource FindAncestor, ListBox, 1}}" /> <Button Content="String2" Command="{Binding DataContext.Command2} RelativeSource={RelativeSource FindAncestor, ListBox, 1}}" /> </StackPanel> </Border> </StackPanel> </DataTemplate> <ListBox.ItemTemplate> </ListBox> I need the SelectedItemVar (dependency property) to update when I click on one of the buttons. SelectedItemVar is then used for the respective button's command. SelectedItemVar does update when I click on the TextBlock or the Border, but not when I click either button. I found a non-MVVM solution to this problem here. I do not want to add code in the file-behind to solve this, as they did in the link. Is there a clean solution that can be done in XAML. Beyond the non-MVVM solutions, I have not found anyone with this problem. I would have thought this was fairly common. Finally, I found this Command="{Binding DataContext.CommandName} RelativeSource={RelativeSource FindAncestor, ListBox, 1} for the Command binding. I do not fully understand what it is doing, but I do know that the command wasn't firing when I was binding directly to CommandName.

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  • Counting string length in javascript and Ruby on Rails

    - by williamjones
    I've got a text area on a web site that should be limited in length. I'm allowing users to enter 255 characters, and am enforcing that limit with a Rails validation: validates_length_of :body, :maximum => 255 At the same time, I added a javascript char counter like you see on Twitter, to give feedback to the user on how many characters he has already used, and to disable the submit button when over length, and am getting that length in Javascript with a call like this: element.length Lastly, to enforce data integrity, in my Postgres database, I have created this field as a varchar(255) as a last line of defense. Unfortunately, these methods of counting characters do not appear to be directly compatible. Javascript counts the best, in that it counts what users consider as number of characters where everything is a single character. Once the submission hits Rails, however, all of the carriage returns have been converted to \r\n, now taking up 2 characters worth of space, which makes a close call fail Rails validations. Even if I were to handcode a different length validation in Rails, it would still fail when it hits the database I think, though I haven't confirmed this yet. What's the best way for me to make all this work the way the user would want? Best Solution: an approach that would enable me to meet user expectations, where each character of any type is only one character. If this means increasing the length of the varchar database field, a user should not be able to sneakily send a hand-crafted post that creates a row with more than 255 letters. Somewhat Acceptable Solution: a javascript change that enables the user to see the real character count, such that hitting return increments the counter 2 characters at a time, while properly handling all symbols that might have these strange behaviors.

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  • BeautifulSoup HTMLParseError. What's wrong with this?

    - by user1915496
    This is my code: from bs4 import BeautifulSoup as BS import urllib2 url = "http://services.runescape.com/m=news/recruit-a-friend-for-free-membership-and-xp" res = urllib2.urlopen(url) soup = BS(res.read()) other_content = soup.find_all('div',{'class':'Content'})[0] print other_content Yet an error comes up: /Library/Python/2.7/site-packages/bs4/builder/_htmlparser.py:149: RuntimeWarning: Python's built-in HTMLParser cannot parse the given document. This is not a bug in Beautiful Soup. The best solution is to install an external parser (lxml or html5lib), and use Beautiful Soup with that parser. See http://www.crummy.com/software/BeautifulSoup/bs4/doc/#installing-a-parser for help. "Python's built-in HTMLParser cannot parse the given document. This is not a bug in Beautiful Soup. The best solution is to install an external parser (lxml or html5lib), and use Beautiful Soup with that parser. See http://www.crummy.com/software/BeautifulSoup/bs4/doc/#installing-a-parser for help.")) Traceback (most recent call last): File "web.py", line 5, in <module> soup = BS(res.read()) File "/Library/Python/2.7/site-packages/bs4/__init__.py", line 172, in __init__ self._feed() File "/Library/Python/2.7/site-packages/bs4/__init__.py", line 185, in _feed self.builder.feed(self.markup) File "/Library/Python/2.7/site-packages/bs4/builder/_htmlparser.py", line 150, in feed raise e I've let two other people use this code, and it works for them perfectly fine. Why is it not working for me? I have bs4 installed...

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  • Typecasting a floating value or using the math.h floor* functions?

    - by nobody
    Hi, I am coding up an implementation of Interpolation Search in C. The question is actually rather simple, I need to use the floating operations to do linear interpolation to find the correct index which will eventually be an integer result. In particular my probe index is: t = i + floor((((k-low)/(high-low)) * (j-i))); where, i,j,k,t are unsigned ints, and high,low are doubles. Would this be equivalent to: t = i + (unsigned int)(((k-low)/(high-low)) * (j-i)); Is there any reason I would actually want to use math.h floor* functions over just a simple (int) typecast?

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  • How does C#'s DateTime.Now affect query plan caching in SQL Server?

    - by Bill Paetzke
    Given: Let's say we have a stored procedure. It reports data back to a user on a webpage. The user can set a date range. If the user sets today's date as the "end date," which includes today's data, the web app passes DateTime.Now to the sql proc. Let's say that one user runs a report--5/1/2010 to now--over and over several times. On the webpage, the user sees "5/1/2010" to "5/4/2010." But the web app passes DateTime.Now to the sql proc as the end date. So, the end date in the proc will always be different, although the user is querying a similar date range. Assume the number of records in the table and number of users are large. So any performance gains matter. Hence the importance of the question. Question: Does passing DateTime.Now as a parameter to a proc prevent SQL Server from caching the query plan? If so, then is the web app missing out on huge performance gains? Possible Solution: I thought DateTime.Today.AddDays(1) would be a possible solution. It would allow the user to get the latest data and always pass the same end date to the sql proc--"5/5/2010" in this case. Please speak to this as well. Sample proc and execution (if that helps to understand): CREATE PROCEDURE GetFooData @StartDate datetime @EndDate datetime AS SELECT * FROM Foo WHERE LogDate >= @StartDate AND LogDate < @EndDate Here's a sample execution using DateTime.Now: EXEC GetFooData '2010-05-01', '2010-05-04 15:41:27' -- passed in DateTime.Now Here's a sample execution using DateTime.Today.AddDays(1) EXEC GetFooData '2010-05-01', '2010-05-05' -- passed in DateTime.Today.AddDays(1) The same data is returned for both procs, since the current time is: 2010-05-04 15:41:27.

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  • About data size filled in the buffer

    - by Bohan Lu
    I need low-latency audio in my project, and I know Android 2.3 supports OpenSL ES. I have read documents and sample code and I decide to use Android simple buffer queue to do the play and record. I now try to write a simple application to do the test. However, I have some questions about recording. If I set the recorder stop when it is recording, how do I know the exact number of bytes filled in the last buffer if it is not filled up ? In 1.1 version, the callback function has some parameters about buffer and its filled data, but there is no such parameters in version 1.0.1. Is there any way to get this information ? Any suggestion would be greatly appreciated !

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  • Remove Duplicates from JavaScript Array

    - by kramden88
    This seems like such a simple need but I've spent an inordinate amount of time trying to do this to no avail. I've looked at other questions on SO and I haven't found what I need. I have a very simple JavaScript array such as peoplenames = new Array("Mike","Matt","Nancy","Adam","Jenny","Nancy","Carl"); that may or may not contain duplicates and I need to simply remove the duplicates and put the unique values in a new array. That's it. I could point to all the codes that I've tried but I think it's useless because they don't work. If anyone has done this and can help me out I'd really appreciate it. JavaScript or jQuery solutions are both acceptable.

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  • Most cost effective way to target multiple mobile platforms

    - by niidto
    Hi I have been given the tasks of speccing a mobile application, which will need to run on approx. 1000 devices. These devices already exist, and consist of iPhones, BlackBerrys, Androids, Windows Mobile and Netbooks. The application will have simple reporting capability, and a collection of forms. Anyway, the obvious solution would be to develop some browser based solution, although given the occasionally connected nature of the devices, there's a potential for data to get lost / not saved. So instead of creating a complex application for each platform, I was thinking we could build what is effectively a form generator, with basic offline storage capability (text files), designed to run on each device, and have the device generate a form, based on for example an XML file that it could request from a server somewhere, resulting in minimal specialist development costs, and the ability to run most of the logic from the server end, with the devices being dumb clients that render forms and upload the data when there is an available connection. Anyway, my question summarised is, how have you made the decision on supporting multiple devices for your application. Is this always an unavoidable problem, and you just have to make the call to support 1 or 2, or pay for developers to write code for each platform, or alternatively supply pre-installed devices to the company? Many thanks James

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  • Is this XSLT correct for the XML file which I have developed?

    - by atrueguy
    This is my XML file. I need to develop a xslt for this. <?xml version="1.0" encoding="ISO-8859-1"?> <!--<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">--> <!-- Generator: Arbortext IsoDraw 7.0 --> <svg width="100%" height="100%" viewBox="0 0 214.819 278.002"> <g id="Standard_x0020_layer"/> <g id="Catalog"> <line stroke-width="0.353" stroke-linecap="butt" x1="5.839" y1="262.185" x2="209.039" y2="262.185"/> <text transform="matrix(0.984 0 0 0.93 183.515 265.271)" stroke="none" fill="#000000" font-family="'Helvetica'" font-size="3.174">© 2009 k Co.</text> <text transform="matrix(0.994 0 0 0.93 7.235 265.3)" stroke="none" fill="#000000" font-family="'Helvetica'" font-size="3.174">087156-8-</text> <text transform="matrix(0.995 0 0 0.93 21.708 265.357)" stroke="none" fill="#000000" font-family="'Helvetica'" font-size="3.174" font-weight="bold">AB</text> <path stroke-width="0.088" stroke-linecap="butt" stroke-dasharray="2.822 1.058" d="M162.037 107.578L174.439 100.417L180.698 104.03"/> <g id="AUTOID_20445" class="52971"> <line stroke-width="0.088" stroke-linecap="butt" x1="68.859" y1="43.621" x2="65.643" y2="45.399"/> <text transform="matrix(0.944 0 0 0.93 69.165 43.356)" stroke="none" fill="#000000" font-family="'Helvetica'" font-size="2.775" font-weight="bold">52971</text> </g> </g> </svg> I have developed a XSLT for this in this way, but I am failing to produce the desired output can any one help me in this. <?xml version="1.0" encoding="ISO-8859-1"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:svg="http://www.w3.org/2000/svg"> <xsl:template match="/"> <fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format"> <fo:layout-master-set> <fo:simple-page-master master-name="simple" page-height="11in" page-width="8.5in"> <fo:region-body margin="0.7in" margin-top="1.15in" margin-left=".8in"/> <fo:region-before extent="1.5in"/> <fo:region-after extent="1.5in"/> <fo:region-start extent="1.5in"/> <fo:region-end extent="1.5in"/> </fo:simple-page-master> </fo:layout-master-set> <fo:page-sequence master-reference="simple"> <fo:flow flow-name="xsl-region-body"> <fo:block> <fo:instream-foreign-object> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" height="100%" width="100%" viewBox="0 0 214.819 278.002"> <xsl:for-each select="svg/g"> <svg:g style="stroke:none;fill:#000000;"> <svg:path> <xsl:variable name="s"> <xsl:value-of select="translate(@d,' ','')"/> </xsl:variable> <xsl:attribute name="d"><xsl:value-of select="translate($s,',',' ')"/></xsl:attribute> </svg:path> </svg:g> </xsl:for-each> <xsl:for-each select="svg/g"> <svg:line x1 = "{$x1}" y1 = "{$y1}" x2 = "{$x2}" y2 = "{$y2}" style = "stroke-width: 0.088; stroke: black;"/> <line xmlns="http://www.w3.org/2000/svg" x1="{$x1}" y1="{$y1}" x2="{$x2}" y2="{$y2}" stroke-width="0.088" stroke="black" fill="#000000" /> </xsl:for-each> </svg:svg> </fo:instream-foreign-object> </fo:block> </fo:flow> </fo:page-sequence> </fo:root> </xsl:template> </xsl:stylesheet> Please help me in this

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  • SQL Server 2008 log size management problems

    - by b0x0rz
    I'm trying to shrink the log of a database AND set the recovery to simple, but always there is an error, whatever i try. USE 4_o5; GO ALTER DATABASE 4_o5 SET RECOVERY SIMPLE; GO DBCC SHRINKFILE (4_o5_log, 10); GO the output of sp_helpfile says that log file is located under (hosted solution): I:\dataroot\4_o5_log.LDF please help me perform this operation as the log file got large when importing a lot of data and now this info is no longer needed, have multiple (lots of) backups since then. the exact error message when performing the query above is: incorrect syntax near '4'. RECOVERY is not a recognized SET option. incorrect syntax near _5_log'. i am using visual studio 2010 (also have SQL Server Express installed locally, SQL Server 2008 proper installed at provider (shared)) thnx a lot

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  • Ternary operator

    - by Antoine Leclair
    In PHP, I often use the ternary operator to add an attribute to an html element if it applies to the element in question. For example: <select name="blah"> <option value="1"<?= $blah == 1 ? ' selected="selected"' : '' ?>> One </option> <option value="2"<?= $blah == 2 ? ' selected="selected"' : '' ?>> Two </option> </select> I'm starting a project with Pylons using Mako for the templating. How can I achieve something similar? Right now, I see two possibilities that are not ideal. Solution 1: <select name="blah"> % if blah == 1: <option value="1" selected="selected">One</option> % else: <option value="1">One</option> % endif % if blah == 2: <option value="2" selected="selected">Two</option> % else: <option value="2">Two</option> % endif </select> Solution 2: <select name="blah"> <option value="1" % if blah == 1: selected="selected" % endif >One</option> <option value="2" % if blah == 2: selected="selected" % endif >Two</option> </select> In this particular case, the value is equal to the variable tested (value="1" = blah == 1), but I use the same pattern in other situations, like <?= isset($variable) ? ' value="$variable" : '' ?>. I am looking for a clean way to achieve this using Mako.

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  • How to retrieve view of MultiIndex DataFrame

    - by Henry S. Harrison
    This question was inspired by this question. I had the same problem, updating a MultiIndex DataFrame by selection. The drop_level=False solution in Pandas 0.13 will allow me to achieve the same result, but I am still wondering why I cannot get a view from the MultiIndex DataFrame. In other words, why does this not work?: >>> sat = d.xs('sat', level='day', copy=False) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 2248, in xs raise ValueError('Cannot retrieve view (copy=False)') ValueError: Cannot retrieve view (copy=False) Of course it could be only because it is not implemented, but is there a reason? Is it somehow ambiguous or impossible to implement? Returning a view is more intuitive to me than returning a copy then later updating the original. I looked through the source and it seems this situation is checked explicitly to raise an error. Alternatively, is it possible to get the same sort of view from any of the other indexing methods? I've experimented but have not been successful. [edit] Some potential implementations are discussed here. I guess with the last question above I'm wondering what the current best solution is to index into arbitrary multiindex slices and cross-sections.

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  • AnkhSVN: Cannot checkout Subsolution due to existing "versioned" folder

    - by lostiniceland
    Hello Everyone I am using Subversion since quite some time for Java-Development and I have setup a repository on my local NAS. Since I have a MSDN subscription via my company I recently installed Visual Studio 2010 to do a small project with .NET. According to some "best-practices" my project folder looks like the following. MySolution main.sln Services services.sln Service A files Service A Test files View projectfiles Persistence persistence.sln PersistenceXml files PersistenceXml Test files PersistenceDB files PersistenceDB Test files The idea is, that the main.sln only contains the projects for the application, meaning no test projects. The subsolutions, contain the project(s) and their corresponding testprojects. I was able to put all those projects under versioncontrol with AnkhSVN, so I have the same structure there in my trunk. Commiting changes was also no problem. Now I would like to check the this out on another machine. I was able to check out the main.sln which downloaded everything that was inside this solution. It skipped the services.sln, persistence.sln and all the test-projects. Until now everything is fine. Now, here comes the problem: when I am tryting to check out the subsolution (eg. services.sln) I get an error, I think it was UnsupportedOperation. I guess this happens because ankhsvn is tryting to download the folder Service A again and create ist hidden .svn folder which is already present. The only workaround I can think of by now is installing Tortoise SVN and check out the whole thing at once. It would be nicer though to have everything from within VS. Does anyone know how I can solve this? Is another client the only solution?

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  • Memorystream and Large Object Heap

    - by Flo
    I have to transfer large files between computers on via unreliable connections using WCF. Because I want to be able to resume the file and I don't want to be limited in my filesize by WCF, I am chunking the files into 1MB pieces. These "chunk" are transported as stream. Which works quite nice, so far. My steps are: open filestream read chunk from file into byet[] and create memorystream transfer chunk back to 2. until the whole file is sent My problem is in step 2. I assume that when I create a memory stream from a byte array, it will end up on the LOH and ultimately cause an outofmemory exception. I could not actually create this error, maybe I am wrong in my assumption. Now, I don't want to send the byte[] in the message, as WCF will tell me the array size is too big. I can change the max allowed array size and/or the size of my chunk, but I hope there is another solution. My actual question(s): Will my current solution create objects on the LOH and will that cause me problem? Is there a better way to solve this? Btw.: On the receiving side I simple read smaller chunks from the arriving stream and write them directly into the file, so no large byte arrays involved.

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  • Tail recursion and memoization with C#

    - by Jay
    I'm writing a function that finds the full path of a directory based on a database table of entries. Each record contains a key, the directory's name, and the key of the parent directory (it's the Directory table in an MSI if you're familiar). I had an iterative solution, but it started looking a little nasty. I thought I could write an elegant tail recursive solution, but I'm not sure anymore. I'll show you my code and then explain the issues I'm facing. Dictionary<string, string> m_directoryKeyToFullPathDictionary = new Dictionary<string, string>(); ... private string ExpandDirectoryKey(Database database, string directoryKey) { // check for terminating condition string fullPath; if (m_directoryKeyToFullPathDictionary.TryGetValue(directoryKey, out fullPath)) { return fullPath; } // inductive step Record record = ExecuteQuery(database, "SELECT DefaultDir, Directory_Parent FROM Directory where Directory.Directory='{0}'", directoryKey); // null check string directoryName = record.GetString("DefaultDir"); string parentDirectoryKey = record.GetString("Directory_Parent"); return Path.Combine(ExpandDirectoryKey(database, parentDirectoryKey), directoryName); } This is how the code looked when I realized I had a problem (with some minor validation/massaging removed). I want to use memoization to short circuit whenever possible, but that requires me to make a function call to the dictionary to store the output of the recursive ExpandDirectoryKey call. I realize that I also have a Path.Combine call there, but I think that can be circumvented with a ... + Path.DirectorySeparatorChar + .... I thought about using a helper method that would memoize the directory and return the value so that I could call it like this at the end of the function above: return MemoizeHelper( m_directoryKeyToFullPathDictionary, Path.Combine(ExpandDirectoryKey(database, parentDirectoryKey)), directoryName); But I feel like that's cheating and not going to be optimized as tail recursion. Any ideas? Should I be using a completely different strategy? This doesn't need to be a super efficient algorithm at all, I'm just really curious. I'm using .NET 4.0, btw. Thanks!

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  • Conceptual question about NSAutoreleasePools

    - by ryyst
    In my Cocoa program, wouldn't a really simple way of dealing with autoreleased objects be to just create a timer object inside the app delegate that calls the following method e.g. every 10 seconds: if (pool) { // Release & drain the current pool to free the memory. [pool release]; } // Create a new pool. pool = [[NSAutoreleasePool alloc] init]; The only problems I can imagine are: 1) If the above code runs in a separate thread, an object might get autoreleased between the release call to the old pool and the creation of the new pool - that seems highly unlikely though. 2) It's obviously not that efficient, because the pool might get released if there's nothing in it. Likewise, in the 10 second gap, many many objects might be autoreleased, causing the pool to grow a lot. Still, the above solution seems pretty suitable to small and simple projects. Why doesn't anybody use it? What's the best practice of using NSAutoreleasePools?

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