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• Flash AS3: crop TextField content off at X lines, add '...' at the end

  - by matt lohkamp

  There's only room for three lines of text in the interface, but the content is external and variable, and if it ends up taking up more than three lines, there needs to be some sort of 'view all' button functionality. I can kind of think about what that function needs to look like, but I'm not quite sure what the best way to do it in AS3 would be. Something like (in pseudo code): function cropText(source:TextField, length:int, append:String):TextField{ if(source.lineCount > length){ source.text = // magic function that retuns the first length lines, // minus append.length characters, with the append value tacked onto the end } return source; } ... right? How would you fill in the missing bit?

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• WordPress contact form email as PDF

  - by lock

  I am using the below code for my WordPress site which is emailing all the form details as an HTML text but I need the details to be written into a PDF first and then have to email the PDF as an attachment. How can I achieve this? This is not a PHP code to use PHP's writePDF modules. So, any idea or any code to implement this? <div style="padding-left: 100px;"> [raw] [contact-form subject="Best Aussie Broker" to="[email protected]"] <div id="main34" style="border: 1px solid black; border-radius: 15px; width: 720px; padding: 15px;"> &nbsp; <h2><span style="color: #ff6600;">Express Application</span></h2> &nbsp; [contact-field label="First Name" type="name" required="true" /] [contact-field label="Last Name" type="text" /] [contact-field label="Email" type="email" required="true" /] [contact-field label="Purpose of Finance?" type="select" options="Home Loan,Refinance,Investment Loan,Debt Consolidation,Other" /] [contact-field label="Your deposit amount" type="text" /] [contact-field label="Amount you need to borrow?" type="text" /] [contact-field label="Brief description of the purpose for finance" type="textarea" required="true" /] <div><label></label> <input class="radio" type="radio" name="19" value="Single Application" onchange="showsingle();" /> <label class="radio">Single Application</label> <div class="clear-form"></div> <input class="radio" type="radio" name="19" value="Joint Application" onchange="showjoint();" /> <label class="radio">Joint Application</label> <div class="clear-form"></div> [contact-field label="Privacy Act" type="checkbox" required="true" /] I have read the Privacy Act 1988 (as Amended) and understand that by selecting the submit button I/we Authorize Best Aussie Broker to act on my/our behalf and manage personal information in relation to this application.<br> <a href="http://googleplex.com.au/pdf.pdf"><img src="http://googleplex.com.au/pdf.png" alt="" /> </a> </div> </div> <div id="single" style="display: none; width: 720px; border: 1px solid black; border-radius: 15px; padding: 15px; margin-top: 10px;"> <div style="padding-top: 10px; width: 720px; text-align: left;"> <h4><span style="color: #ff6600;">Last step then we will get all listed Australian vendors to fight it out for your best deal</span></h4> </div> <div> <label class="select" for="19-date-of-birth">Date of Birth</label> [contact-field label="Day" type="select" options="1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31" /] [contact-field label="Month" type="select" options="January,February,March,April,May,June,July,August,September,October,November,December" /] [contact-field label="Year" type="select" options="2000,1999,1998,1997,1996,1995,1994,1993,1992,1991,1990,1989,1988,1987,1986,1985,1984,1983,1982,1981,1980,1979,1978,197,1976,1975,1974,1973,1972,1971,1970,1969,1968,1967,1966,1965,1964,1963,1962,1961,1960,1959,1958,1957,1956,1955,1954,1953,1952,1951,1950,1949,1948,1947,1946,1945,1944,1943,1942,1941,1940,1939,1938,1937,1936,1935,1934,1933,1932,1931,1930,1929,1928,1927,1926,1925,1924,1923,1922,1921,1920, 1919,1918,1917,1916,1915,1914,1913,1912,1911,1910,1909" /] </div> [contact-field label="Address" type="text" /] [contact-field label="Suburb" type="text" /] [contact-field label="Postcode" type="text" /] <div> [contact-field label="State" type="select" options="VIC,NSW,QLD,SA,WA,TAS,NZ,Other" /] </div> [contact-field label="Best Contact" type="radio" options="Landline,Mobile" /] [contact-field label="Phone Number" type="text" /] [contact-field label="Marital Status" type="select" options="Married,Single,Other" /] [contact-field label="Residential Status" type="select" options="Renting, Home Owned, Home Mortgage, Board, Other" /] [contact-field label="Children/Dependents" type="select" options="0,1,2,3,4,5,6" /] <div></div> [contact-field label="Gross Yearly Income" type="text" /] [contact-field label="Current Employer" type="text" /] <div> <label class="select" for="19-year-of-empl">Time at this employer</label> [contact-field label="Year" type="select" options="0,1,2,3,4,5,6,7,8,9,10,More" /] [contact-field label="Month" type="select" options="0,1,2,3,4,5,6,7,8,9,10,11,12" /] </div> <div style="padding-right: 15px;"></div> </div> <div id="joint" style="display: none; width: 720px; border: 1px solid black; border-radius: 15px; padding: 15px; margin-top: 10px;"> <div style="padding-top: 10px; width: 720px; text-align: left;"> <h4><span style="color: #ff6600;">Last step then we will get all listed Australian vendors to fight it out for your best deal</span></h4> </div> <div style="float: left; width: 320px;"> <div> <label class="select" for="19-date-of-birth1">Date of Birth</label> [contact-field label="Day" type="select" options="1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31" /] [contact-field label="Month" type="select" options="January,February,March,April,May,June,July,August,September,October,November,December" /] [contact-field label="Year" type="select" options="2000,1999,1998,1997,1996,1995,1994,1993,1992,1991,1990,1989,1988,1987,1986,1985,1984,1983,1982,1981,1980,1979,1978,197,1976,1975,1974,1973,1972,1971,1970,1969,1968,1967,1966,1965,1964,1963,1962,1961,1960,1959,1958,1957,1956,1955,1954,1953,1952,1951,1950,1949,1948,1947,1946,1945,1944,1943,1942,1941,1940,1939,1938,1937,1936,1935,1934,1933,1932,1931,1930,1929,1928,1927,1926,1925,1924,1923,1922,1921,1920, 1919,1918,1917,1916,1915,1914,1913,1912,1911,1910,1909" /] </div> [contact-field label="Address" type="text" /] [contact-field label="Suburb" type="text" /] [contact-field label="Postcode" type="text" /] <div> [contact-field label="State" type="select" options="VIC,NSW,QLD,SA,WA,TAS,NZ,Other" /] </div> [contact-field label="Best Contact" type="radio" options="Landline,Mobile" /] [contact-field label="Phone Number" type="text" /] <div></div> <div></div> [contact-field label="Marital Status" type="select" options="Married,Single,Other" /] [contact-field label="Residential Status" type="select" options="Renting, Home Owned, Home Mortgage, Board, Other" /] [contact-field label="Children/Dependents" type="select" options="0,1,2,3,4,5,6" /] <div></div> <div><label class="text" for="netincome">Net Income</label> <input id="netincome" type="text" name="netincome" /> <select id="netincome-dropdown" name="netincome-dropdown"> <option>Monthly</option> <option>Yearly</option> </select></div> [contact-field label="Current Employer" type="text" /] <div> <label class="select" for="19-year-of-empl2">Time at this employer</label> [contact-field label="Year" type="select" options="0,1,2,3,4,5,6,7,8,9,10,More" /] [contact-field label="Month" type="select" options="0,1,2,3,4,5,6,7,8,9,10,11,12" /] </div> </div> <div style="float: right; width: 320px; padding-right: 50px;"> <div> <label class="select" for="19-date-of-birth3">Date of Birth</label> [contact-field label="Day" type="select" options="1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31" /] [contact-field label="Month" type="select" options="January,February,March,April,May,June,July,August,September,October,November,December" /] [contact-field label="Year" type="select" options="2000,1999,1998,1997,1996,1995,1994,1993,1992,1991,1990,1989,1988,1987,1986,1985,1984,1983,1982,1981,1980,1979,1978,197,1976,1975,1974,1973,1972,1971,1970,1969,1968,1967,1966,1965,1964,1963,1962,1961,1960,1959,1958,1957,1956,1955,1954,1953,1952,1951,1950,1949,1948,1947,1946,1945,1944,1943,1942,1941,1940,1939,1938,1937,1936,1935,1934,1933,1932,1931,1930,1929,1928,1927,1926,1925,1924,1923,1922,1921,1920, 1919,1918,1917,1916,1915,1914,1913,1912,1911,1910,1909" /] </div> [contact-field label="Address" type="text" /] [contact-field label="Suburb" type="text" /] [contact-field label="Postcode" type="text" /] <div> [contact-field label="State" type="select" options="VIC,NSW,QLD,SA,WA,TAS,NZ,Other" /] </div> [contact-field label="Best Contact" type="radio" options="Landline,Mobile" /] [contact-field label="Phone Number" type="text" /] <div></div> <div></div> [contact-field label="Marital Status" type="select" options="Married,Single,Other" /] [contact-field label="Residential Status" type="select" options="Renting, Home Owned, Home Mortgage, Board, Other" /] [contact-field label="Children/Dependents" type="select" options="0,1,2,3,4,5,6" /] <div></div> <div><label class="text" for="netincome">Net Income</label> <input id="netincome" type="text" name="netincome" /> <select id="netincome-dropdown" name="netincome-dropdown"> <option>Monthly</option> <option>Yearly</option> </select></div> [contact-field label="Current Employer" type="text" /] <div> <label class="select" for="19-year-of-empl">Time at this employer</label> [contact-field label="Year" type="select" options="0,1,2,3,4,5,6,7,8,9,10,More" /] [contact-field label="Month" type="select" options="0,1,2,3,4,5,6,7,8,9,10,11,12" /] </div> </div> <div style="clear: both;"></div> <div></div> </div> &nbsp; [/contact-form][/raw] </div>

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• How to make Excel strip ALL quotes from CSV text fields

  - by Klay

  When importing a CSV file into Excel, it only strips the double-quotes from the FIRST field on the line, but leaves them on all other fields. How can I force Excel to strip the quotes from ALL strings? For instance, I have a CSV file: "text1", "text2", "numeric1", "numeric 2" "abc", "def", 123, 456 "abc", "def", 123, 456 "abc", "def", 123, 456 "abc", "def", 123, 456 I import it into Excel using Data Import External Data Import Data. I specify that the fields are delimited by commas, and that the text delimiter is the double-quote character. Both the data preview and the actual Excel spreadsheet columns only strip the double-quotes from the first text field. All other text fields still have quotes around them. What's really strange is that Access is able to import this data correctly (i.e. strips quotes from every text field. Note that this is NOT a matter of internal commas or quotes or escape characters. This happens in Excel 2003 and Excel 2007.

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• Should I replace string patterns in asp.net mvc using a custom viewengine?

  - by Roger Rogers

  Have an ASP.NET MVC site that is localized. The localization functionality adds the two digit language ID to the URL, e.g. /es/Page. If no language Id is found in the URL, the site switches to the user's browser culture. All's good. However, the site's hyperlinks, a mixture of hard-coded href tags, actionlinks, etc., don't include the base language ID, so when clicking through the site the set culture is lost, and the site reverts to the user's browser culture. My (lazy) thought is to replace all href values, that don't point to an external site, with the localized URL (e.g. include the /es/). Otherwise, all site links will need to be updated to include the culture code. Is this just plain dumb? Or, reasonable, and should be done using a custom view engine, or some other approach?

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• Eclipse and python: library will import in interprer, but not in IDE

  - by John

  I'm running Windows 7, Python 2.6.4 and the latest version of Eclipse. I downloaded the boto library (http://code.google.com/p/boto/) and ran python setup.py install, which created boto-1.9b-py2.6.egg in C:\Python26\Lib\site-packages. Importing a class - say, by doing 'from boto.sqs.connection import SQSConnection' - works fine from the python command line tool. But Eclipse will not find boto, despite the fact that it is using the same python interpreter as I am using when at the command line. I added the library as an external source folder, but that didn't work either. How can I properly import the boto library into Eclipse? Thanks.

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• MonoDevelop: error VBNC99999

  - by teo

  Hi at all guys, hope someone is using Mono & monodevelop... i'm getting the following error when i try to compile an ASP.NET apps ported from vs.net 2008 Error VBNC99999: Unexpected error: The classes in the module cannot be loaded. (VBNC99999) This is the only error i get. I'm using 4 external assembly / dll AjaxControlToolkit.dll FusionCharts.dll MySql.Data.dll PostBackRitalin.dll I've added the dll in bin directory, then i've referenced it. I'm using Mono, because on my "old" computer (acer aspire t2300 buyed in 2007) run with linux & with monodevelop very well. With windows, visual studio is reeeeeeally slow.. so i decide to pass to mono.. Can somenone know something about that error ? Thank you very much. Regards !

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• Looking for an automated logging tool/library for .NET!

  - by tsocks

  Hello, I'm looking for an library/tool for .NET that logs almost everything that happens in my C# application (Windows Form). The problem is that I'm delivering an application to a client (Windows XP) and after doing some task, that classic Microsoft error window appears: "ApplicationName has encountered a problem and needs to close. We are sorry for the inconvenience" I'm currently handling my application exceptions, but this is something external and I can't get anything from that error, so I would like any automated library that helps me with that. It would work if it logs each line of code executed, orr just log what line was executing before that error appeared, or something that could give me more info about that error. Thank you! P.S: It's a multithreaded application, and have to Timer controls (one for watching a folder every 5secs, and another for watching thread list...). I'm using Windows 7 here and everything seems to work ok.

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• htaccess rewrite issue while testing on localhost

  - by James Doc

  I'm running OSX (10.6) with Apache with .htaccess enabled. In the htaccess file I have the code: Options +FollowSymlinks RewriteEngine on RewriteRule ^page/([A-Z0-9._%+-]+) index.php?page=$1 [NC] This runs perfectly on my external server and redirects nicely to index.php?page=whatever However when testing locally from localhost/~james/In%20Progress/Vila%20Maninga/page/whatever I get redirected to localhost/~james/Users/James/Sites/In%20Progress/Vila%20Maninga/index.php?page=whatever. For some reason 'Users/James/Sites/' is being added. Does anyone why this is happening and how to prevent it? Many thanks, James

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• How can I use Code Contracts in a C++/CLI project?

  - by Daniel Wolf

  I recently stumbled upon Code Contracts and have started using them in my C# projects. However, I also have a number of projects written in C++/CLI. For C# and VB, Code Contracts offer a handy configuration panel in the project properties dialog. For a C++/CLI project, there is no such panel. From the documentation, I got the impression that adding Code Contracts support to a C++/CLI project should be a simple matter of calling some external tools as part of the build process (namely ccrefgen.exe, cccheck.exe, and ccrewrite.exe). However, the number of command line options and restrictions concerning the call sequence have me somewhat intimidated. Can anybody point me to a simple way to run the Code Contracts tools as an automated part of the build process in Visual Studio?

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• silverlight for .NET / CLR based numerical computing on osx

  - by Jonathan Shore

  I'm interested in using F# for numerical work, but my platforms are not windows based. Mono still has a significant performance penalty for programs that generate a significant amount of short-lived objects (as would be typical for functional languages). Silverlight is available on OSX. I had seen some reference indicating that assemblies compiled in the usual way could not be referenced, but not clear on the details. I'm not interested in UIs, but wondering whether could use the VM bundled with silverlight effectively for execution? I would want to be able to reference a large library of numerical models I already have in java (cross-compiled via IKVM to .NET assemblies) and a new codebase written in F#. My hope would be that the silverlight VM on OSX has good performance and can reference external assemblies and native libraries. Is this doable?

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• Plotting 3-tuple data points in a surface / contour plot using matplotlib

  - by morpheous

  I have some surface data that is generated by an external program as XYZ values. I want to create the following graphs, using matplotlib: Surface plot Contour plot Contour plot overlayed with a surface plot I have looked at several examples for plotting surfaces and contours in matplotlib - however, the Z values seems to be a function of X and Y i.e. Y ~ f(X,Y). I assume that I will somehow need to transform my Y variables, but I have not seen any example yet, that shows how to do this. So, my question is this: given a set of (X,Y,Z) points, how may I generate Surface and contour plots from that data? BTW, just to clarify, I do NOT want to create scatter plots. Also although I mentioned matplotlib in the title, I am not averse to using rpy(2), if that will allow me to create these charts.

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• Can I use XText for a DSL involving an XML file type?

  - by Chris

  I have defined a small DSL that is mostly written in the form of different types of XML files in conjuction with some property files. This works very well but I wish to create an Eclipse Editor to make editing these files easier for beginners (I already have a working parser). The main XML file can reference some items from the .properties files and vice-versa. THe main xml file can also reference other XML files. Certain options should only be available in the main xml file based on the contents of the .properties files and based on some osgi plugins that can be added to the DSL project (the syntax is dynamic depending on context). The structure of the language is fixed but the options available in each attribute or the choice of attributes themselves changes depending on metadata contained in plugin .jar files. Questions: Does XText support dynamic syntax (validation changes depending on external factors)? Does XText support XML files / .properties files? Thank you very much for your help in advance.

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• MLS Integration (RETSBond RI or?)

  - by prodigitalson

  I'm looking Specifically for some detailed information on RETSBond Integrator (RI) or something similar. Has anyone used it? Drawbacks? benefits? What I need is something that provides a PHP API out of the box or some kind of RPC exposure. This thing seems to provide an API for batching the MLS server and putting in my own DB which is acceptable although ideally I'd prefer something totally external. Do any MLS services provide that that you are aware of? I realize this is somewhat subjective but I'm looking for a starting point on different services/vendors to research.

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• How to make teamcity's svn checkout more verbose?

  - by Benju

  We have a very large svn external containing about 30,000 500k files. This checkout can take a long time and we would like to see the progress in the TeamCity logs as it happens. Is there a way to use a more verbose logging when doing the svn checkout than just.... [19:26:00]: Updating sources: Agent side checkout... [19:26:00]: [Updating sources: Agent side checkout...] Will perform clean checkout. Reason: Checkout directory is empty or doesn't exist [19:26:00]: [Updating sources: Agent side checkout...] Cleaning /opt/TeamCity/buildAgent/work/937995fe3d15f1e7 [19:26:00]: [Updating sources: Agent side checkout...] VCS Root: guru 6 trunk with externals [19:26:00]: [VCS Root: guru 6 trunk with externals] revision: 6521_2010/04/27 19:25:58 -0500

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• GC.AddMemoryPressure in C#

  - by ssheldon

  I am writing an application in C# that makes use of a 3rd party COM DLL, this dll creates a lot of resources (like bitmaps, video, data structures) in unmanaged memory. While digging around I came across the following call for the Garbage Collector: GC.AddMemoryPressure(long long bytesAllocated) It is documented in MSDN here: http://msdn.microsoft.com/en-us/library/system.gc.addmemorypressure.aspx This sounds like something I should be calling since this external dll is createing a lot of resources the CLR is unaware of. I guess I have two questions... How do I know how much memory pressure to add when the dll is 3rd party and it's not possible for me to know exactly how much memory this dll is allocating. How important is it to do this?

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• How to modularize a b2b webservice transformation application

  - by hstoerr

  How would you modularize a large application that has some incoming (SOAP) webservices, some outgoing webservices, transformations between them and internal formats, internal logging services, accesses external archiving webservices, delays stuff and works on this asynchronously and so forth? One way is to split the functionality into a collection of WAR, deploy all of them on one application server and have them communicate with internal webservices. This has some overhead, especially if the messages are large, and you might run into performance problems due to thread count restrictions and so forth. Another way would be to put everything into a giant WAR, such that you can communicate directly. Not exactly modularization. What would you do?

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• How come ftp protocol produces transmission errors sometimes if the data is using TCP, which is checksummed?

  - by Cray

  Every once in a while, downloading (especially large) files through ftp will produce errors. I am guessing that's also partly the reason why all major sites are publishing external checksums along with their downloads. How is this possible if ftp goes through TCP, which has checksum inbuilt and resends data if it is transmitted corruptly? One could argue that this is due to the short length of the CRC in the TCP protocol (which is 16bit I think, or something like that), and the collisions are simply happening too often. but 1) for this to be true, not only must there be a CRC collision, but also the random network error must modify both the CRC in the packet, and the packet itself so that the CRC will be valid for the new packet... Even with 16 bitCRC, is that so likely? 2) There are seemingly not many errors in, say, browsing the web which also goes through TCPIP.

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• How to access web server of any machine of my network from the outside

  - by Luc

  Hello, I have an ip like username.dyndns.org, this is the external IP of my router. On my lan, I have several machine (m1, m2, ...) , each running a dedicated web server. Is it possible to reach each machine from the outside with something like: http://m1.username.dyndns.org http://m2.username.dyndns.org ? Do you know what needs to be configured in my router for NAT ? Also, is there a special directive in Apache to do so ? Thanks a lot, Regards, Luc

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• Is it possible to compile IronRuby code to a .NET assembly (EXE or DLL)

  - by Chris Ammerman

  My scenario consists of the following points. I have a packaged software product I am developing in C# Since it is a packaged product, the public interfaces of the assemblies need to be tightly controlled... All assemblies are strong-named Any classes that don't absolutely have to be "public" are "internal" I want to write unit tests for those "internal" classes, since they are the bulk of the code And finally.... I want to try writing the unit tests in Ruby. Since the unit tests would be external to the assembly containing the code under test, the assemblies under test would each need to have an "InternalsVisibleTo" attribute specifying the name of the unit test assembly. Which of course would mean that the Ruby unit tests would have to compile down to a .NET assembly so they can be given access in this way. Can this be done? If so, how? All I can find on the web about "compiling IronRuby" is about building the actual IronRuby runtime from source.

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• Image Uploading - security issues

  - by TenaciousImpy

  Hi, I'm developing an ASP.NET Web app and would like the user to be able to either upload an image from their local system, or pass in a URL to an image. The image can either be a JPG or PNG. What security issues should I be concerned about doing this? I've seen various ways of embedding code within JPG files. Are there any methods in C# (or external libraries) which can confirm that a file is a JPG/PNG, otherwise throw an error? At the very least, I'm making the directory which holds uploaded images non-browsable and putting a max size limit of 1mb, but I'd like to implement further checks. Thanks for any advice.

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• How to check for duplicate files?

  - by miorel

  I have an external hard drive on which I have backed up files several times. Some files were modified between backups, others were not. Some may have been renamed. Now I'm running out of space, and I'd like to clean up duplicate files. My idea was to md5sum every file on the drive, then look for duplicates, and diff the relevant files (just in case, haha). Is this the best way to do this? What are some other methods of checking for duplicate files?

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• How to use Obj-C classes in MacRuby

  - by beno1604

  I am trying to use an external Obj-C class in my MacRuby project, but I can't figure out how to import it. Specifically, I want to use ObjectiveResource inside a MacRuby 0.5 project (since ActiveResource doesn't work - yet). I have gotten as far as the 'framework' command in MacRuby, but it only seems to apply to actual frameworks. Questions: where should I install the objective-resource directory? how do I pull these classes inside my ruby code? Thanks for any help!

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• VS2010 MVC and Entity Framework Model in Separate Project

  - by mdm

  Hi, I am trying to use an Entity Framework Model (in separate project) into an asp.net 4 MVC project (VS2010, C#) If I create the EF inside the MVC project I have no problems. I think I am missing some step. things done: 1. added reference to the EF class project 2. added connection string in MVC web.config 3. added reference to System.Data.Entity in both web.config and project references Now i can use the model only if I copy the .edmx file to the Models folder, but in this way the EF project is not external anymore. What am I missing? Thank you in advance.

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• How to add custom hooks to controllers in ASP.NET MVC2

  - by Adrian

  Hi, I've just started a new project in ASP.net 4.0 with MVC 2. What I need to be able to do is have a custom hook at the start and end of each action of the controller. e.g. public void Index() { *** call to the start custom hook to externalfile.cs (is empty so does nothing) ViewData["welcomeMessage"] = "Hello World"; *** call to the end custom hook to externalfile.cs (changes "Hello World!" to "Hi World") return View(); } The View then see welcomeMessage as "Hi World" after being changed in the custom hook. The custom hook would need to be in an external file and not change the "core" compiled code. This causes a problem as with my limited knowledge ASP.net MVC has to be compiled. Does anyone have any advice on how this can be achieved? Thanks

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• Making swap faster, easier to use and exception-safe

  - by FredOverflow

  I could not sleep last night and started thinking about std::swap. Here is the familiar C++98 version: template <typename T> void swap(T& a, T& b) { T c(a); a = b; b = c; } If a user-defined class Foo uses external ressources, this is inefficient. The common idiom is to provide a method void Foo::swap(Foo& other) and a specialization of std::swap<Foo>. Note that this does not work with class templates since you cannot partially specialize a function template, and overloading names in the std namespace is illegal. The solution is to write a template function in one's own namespace and rely on argument dependent lookup to find it. This depends critically on the client to follow the "using std::swap idiom" instead of calling std::swap directly. Very brittle. In C++0x, if Foo has a user-defined move constructor and a move assignment operator, providing a custom swap method and a std::swap<Foo> specialization has little to no performance benefit, because the C++0x version of std::swap uses efficient moves instead of copies: #include <utility> template <typename T> void swap(T& a, T& b) { T c(std::move(a)); a = std::move(b); b = std::move(c); } Not having to fiddle with swap anymore already takes a lot of burden away from the programmer. Current compilers do not generate move constructors and move assignment operators automatically yet, but as far as I know, this will change. The only problem left then is exception-safety, because in general, move operations are allowed to throw, and this opens up a whole can of worms. The question "What exactly is the state of a moved-from object?" complicates things further. Then I was thinking, what exactly are the semantics of std::swap in C++0x if everything goes fine? What is the state of the objects before and after the swap? Typically, swapping via move operations does not touch external resources, only the "flat" object representations themselves. So why not simply write a swap template that does exactly that: swap the object representations? #include <cstring> template <typename T> void swap(T& a, T& b) { unsigned char c[sizeof(T)]; memcpy( c, &a, sizeof(T)); memcpy(&a, &b, sizeof(T)); memcpy(&b, c, sizeof(T)); } This is as efficient as it gets: it simply blasts through raw memory. It does not require any intervention from the user: no special swap methods or move operations have to be defined. This means that it even works in C++98 (which does not have rvalue references, mind you). But even more importantly, we can now forget about the exception-safety issues, because memcpy never throws. I can see two potential problems with this approach: First, not all objects are meant to be swapped. If a class designer hides the copy constructor or the copy assignment operator, trying to swap objects of the class should fail at compile-time. We can simply introduce some dead code that checks whether copying and assignment are legal on the type: template <typename T> void swap(T& a, T& b) { if (false) // dead code, never executed { T c(a); // copy-constructible? a = b; // assignable? } unsigned char c[sizeof(T)]; std::memcpy( c, &a, sizeof(T)); std::memcpy(&a, &b, sizeof(T)); std::memcpy(&b, c, sizeof(T)); } Any decent compiler can trivially get rid of the dead code. (There are probably better ways to check the "swap conformance", but that is not the point. What matters is that it's possible). Second, some types might perform "unusual" actions in the copy constructor and copy assignment operator. For example, they might notify observers of their change. I deem this a minor issue, because such kinds of objects probably should not have provided copy operations in the first place. Please let me know what you think of this approach to swapping. Would it work in practice? Would you use it? Can you identify library types where this would break? Do you see additional problems? Discuss!

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