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• google maps api keys to be set webserver-wide, (as env var? inside apache?)

  - by ~knb

  I have a web site with many virtual hosts and each registered with several domain names (ending in .org, .de), site1.mysite.de, site2.mysite.org Then I have different templating systems based on several programming languages (perl and php) in use on the web server. The Google Maps Api requires a unique Google Maps api key for each vhost. I want to have something like a web-server wide variable $goomapkey that I can call from inside my code. In PHP code, Now I have a kludgy case-analysis solution like $domain = substr($_SERVER['SERVER_NAME'], -3); if (".de" == $domain){ //if ("xxxxxx" eq substr($ENV{SERVER_NAME}, 0, 5)){ // $gookey = "ABQIAAA..."; //} else { //site1.de $gookey = "ABQIAAAA1Js..."; //} } elseif ("dev" == substr($_SERVER['SERVER_NAME'], 0, 3)){ //dev.mysite.org $gookey = "ABQIAAAA1JsSb..."; } else { //www.mysite.org $gookey = "ABQIAAAA1JsS..."; //TODO: Add more keys for each virtual host, for my.machinename.de, IP-address based URL, ... } ... inside my php-based CMS. A non-ideal solution, because it is, php-only, and I still have to set it at several html templates inside the CMS, and there are too many cases. I want the google maps api key to be set by the apache web server who examines the request *early in the request loop before any php page template code is constructed and evaluated. is an environment variable a good solution? which technology should be used to set the $goomapkey variable? I'd prefer mod_perl2 Apache request handler, but the documentation is confusing (many API changes in the past ). Which Apache module could I use? Is there a built-in Apache module that does the same thing?

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• Fastest way to clamp a real (fixed/floating point) value?

  - by Niklas

  Hi, Is there a more efficient way to clamp real numbers than using if statements or ternary operators? I want to do this both for doubles and for a 32-bit fixpoint implementation (16.16). I'm not asking for code that can handle both cases; they will be handled in separate functions. Obviously, I can do something like: double clampedA; double a = calculate(); clampedA = a > MY_MAX ? MY_MAX : a; clampedA = a < MY_MIN ? MY_MIN : a; or double a = calculate(); double clampedA = a; if(clampedA > MY_MAX) clampedA = MY_MAX; else if(clampedA < MY_MIN) clampedA = MY_MIN; The fixpoint version would use functions/macros for comparisons. This is done in a performance-critical part of the code, so I'm looking for an as efficient way to do it as possible (which I suspect would involve bit-manipulation) EDIT: It has to be standard/portable C, platform-specific functionality is not of any interest here. Also, MY_MIN and MY_MAX are the same type as the value I want clamped (doubles in the examples above).

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• Specifying SOAP Headers for a Zend_Soap Service

  - by Stephen

  I have a generally straight forward web service that I've written (converting code to ZF from a Java implementation of the same service and trying to maintain the same wsdl structure as much as possible). The service loads a PHP class, rather than individual functions. The PHP class contains three different functions within it. Everything seems to be working just fine, except that I can't seem to figure out how to specify that a given function parameter should be passed as a SOAP header. I've not seen any mention of SOAP headers in the Server context, only how to pass header parameters with a client to a server. In addition to the standard parameters for the function that would be sent in the SOAP body and detailed in the docblock, I would like to specify two parameters (a username and password) that would be sent in a SOAP header. I have to assume this is possible, but haven't been able to find anything online, nor have I had any responses to a similar post on Zend's forum. Is there something that can be added in the docblock area to specify a parameter as a header (maybe in a similar fashion to using WebParam?)? Any suggestions/examples on how to get this accomplished would be greatly appreciated!

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• Calling function after .load (Jquery)

  - by Matt

  Having a little difficulty getting a function to call after a .load: $(function(){ $('a.pageFetcher').click(function(){ $('#main').load($(this).attr('rel')); }); }); The page loads, but the functions don't fire: $(function(){ var $container = $('#container'); $container.imagesLoaded(function(){ $container.masonry({ itemSelector: '.box', }); }); $container.infinitescroll({ navSelector : '#page-nav', nextSelector : '#page-nav a', itemSelector : '.box', loading: { finishedMsg: 'Nothing else to load.', img: 'http://i.imgur.com/6RMhx.gif' } }, function( newElements ) { $.superbox.settings = { closeTxt: "Close this", loadTxt: "Loading your selection", nextTxt: "Next item", prevTxt: "Previous item" }; $.superbox(); var $newElems = $( newElements ).css({ opacity: 0 }); $newElems.imagesLoaded(function(){ $newElems.animate({ opacity: 1 }); $container.masonry( 'appended', $newElems, true ); }); } ); }); I've attempted to combine them so that the 2nd functions are called after .load (after doing some searching on this site and looking at given answers/examples) but nothing seems to work properly. Suggestions?

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• Creating PHP strings using other variables...works manually, can't figure out how automatically

  - by Matt

  Hello, I'm trying to get a variable to be formed automatically using data pulled from a mysql database. I know the data is being pulled from the database in some form resembling its original form, but that data does not act the same as data that is manually typed and assigned to a string. For example, if a cell in a mysql table says... I said "goodbye" before I left. She also said "goodbye." ...and I manually copy/paste it and add the necessary escapes... $string1 = " I said \"goodbye\" before I left. She also said \"goodbye.\" "; ...that does not equal... $string1 = $mysqlResultArray['specificCellWithQuoteShownAbove'] Interestingly, if I echo both versions of $string1 and view the output, they appear to be exactly the same. But they do not function the same when put through various functions I've created. The functions only work if I do the manual copy/paste method--which is not what I want, obviously. I'm not sure if it has to do with the line breaks or the escapes--or some combination of the two. But while both strings are superficially the same, they are apparently functionally different and I don't know why. So how can I create $string1 without manually copy/pasting the contents from the mysql entry and instead querying for the data and assigning it to $string1 in such a way that it's exactly functionally equivalent as the manual copy/pasted string?

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• How to structure this Symfony web project?

  - by James William

  I am new to Symfony and am not sure how to best structure my web project. The solution must accommodate 3 use cases: Public access to www.mydomain.com for general use Member only access to member.mydomain.com Administrator access to admin.mydomain.com All three virtual hosts point to the Symfony /web directory Questions: Is this 3 separate applications in my Symfony project (e.g. "frontend", "backend" and "admin" or "public", "member", "admin")? Is this a good approach if there is to be some duplicate code (e.g. generating a member list would be common across all 3 applications, but presented differently)? How would I route to the various applications based on the subdomain when a user accesses *.mydomain.com? Where in Symfony should this routing logic be placed? Or, is this one application with modules for each of the above use cases? EDIT: I do not have access to httpd.conf in apache to specify a default page for virtual hosts. I can only specify a directory for each subdomain using the hostin provider's cPanel.

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• Recommendations for IPC between parent and child processes in .NET?

  - by Jeremy

  My .NET program needs to run an algorithm that makes heavy use of 3rd party libraries (32-bit), most of which are unmanaged code. I want to drive the CPU as hard as I can, so the code runs several threads in parallel to divide up the work. I find that running all these threads simultaneously results in temporary memory spikes, causing the process' virtual memory size to approach the 2 GB limit. This memory is released back pretty quickly, but occasionally if enough threads enter the wrong sections of code at once, the process crosses the "red line" and either the unmanaged code or the .NET code encounters an out of memory error. I can throttle back the number of threads but then my CPU usage is not as high as I would like. I am thinking of creating worker processes rather than worker threads to help avoid the out of memory errors, since doing so would give each thread of execution its own 2 GB of virtual address space (my box has lots of RAM). I am wondering what are the best/easiest methods to communicate the input and output between the processes in .NET? The file system is an obvious choice. I am used to shared memory, named pipes, and such from my UNIX background. Is there a Windows or .NET specific mechanism I should use?

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• Length-1 arrays can be converted to python scalars error? python

  - by Randy

  from numpy import * from pylab import * from math import * def LogisticMap(a,x): return 4.*a*x*(1.-x) def CosineMap(a,x): return a*cos(x/(2.*pi)) def TentMap(a,x): if x>= 0 or x<0.5: return 2.*a*x if x>=0.5 or x<=1.: return 2.*a*(1.-x) a = 0.98 N = 40 xaxis = arange(0.0,N,1.0) Func = CosineMap subplot(211) title(str(Func.func_name) + ' at a=%g and its second iterate' %a) ylabel('X(n+1)') # set y-axis label plot(xaxis,Func(a,xaxis), 'g', antialiased=True) subplot(212) ylabel('X(n+1)') # set y-axis label xlabel('X(n)') # set x-axis label plot(xaxis,Func(a,Func(a,xaxis)), 'bo', antialiased=True) My program is supposed to take any of the three defined functions and plot it. They all take in a value x from the array xaxis from 0 to N and then return the value. I want it to plot a graph of xaxis vs f(xaxis) with f being any of the three above functions. The logisticmap function works fine, but for CosineMap i get the error "only length-1 arrays can be converted to python scalars" and for TentMap i get error "The truth value of an array with more than one element is ambiguous, use a.any() or a.all()". My tent map function is suppose to return 2*a*x if 0<=x<0.5 and it's suppose to return 2*a*(1-x) if 0.5<=0<=1.

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• What is the difference between these two linq implementations?

  - by Mahesh Velaga

  I was going through Jon Skeet's Reimplemnting Linq to Objects series. In the implementation of where article, I found the following snippets, but I don't get what is the advantage that we are gettting by splitting the original method into two. Original Method: // Naive validation - broken! public static IEnumerable<TSource> Where<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { if (source == null) { throw new ArgumentNullException("source"); } if (predicate == null) { throw new ArgumentNullException("predicate"); } foreach (TSource item in source) { if (predicate(item)) { yield return item; } } } Refactored Method: public static IEnumerable<TSource> Where<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { if (source == null) { throw new ArgumentNullException("source"); } if (predicate == null) { throw new ArgumentNullException("predicate"); } return WhereImpl(source, predicate); } private static IEnumerable<TSource> WhereImpl<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { foreach (TSource item in source) { if (predicate(item)) { yield return item; } } } Jon says - Its for eager validation and then defferring for the rest of the part. But, I don't get it. Could some one please explain it in a little more detail, whats the difference between these 2 functions and why will the validations be performed in one and not in the other eagerly? Conclusion/Solution: I got confused due to my lack of understanding on which functions are determined to be iterator-generators. I assumed that, it is based on signature of a method like IEnumerable<T>. But, based on the answers, now I get it, a method is an iterator-generator if it uses yield statements.

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• Creating Modules for VB Program (Similar to firefox add on)

  - by Assimilater

  Hi all. I have a contact manager program that I'd like to design for multiple network marketing companies. My desired structure would include a core program which covers basic contact management functions. After that one could purchase a module for their specific network marketing company. This module would contain a variety of controls that the original program would need to be able to manipulate. Here is an example of what it would have to have: A group box containing buttons that link to a genealogy view, and the option to import one's donwnline from the back office provided by a company. A panel which is displayed on the contact page allowing the user to input business information or which will be filled by importing a downline from the back office: ie business ID, qualification level, sponsor information etc. a panel displayed when one searches for contacts on the contact list page which allows the user to sort based on information such as when they joined, what their business id is and so forth. a panel which is displayed in a personal business overview page which presents to an individual how many people in their downline are at each qualification level and develop a mailing list for individuals of a certain qualification level. I have the code developed to perform all these functions, I just wanted to give you an example of what needed to be done. I'm thinking that what I'm trying to create is a library that one can download and the program will recognize, but I'm not really sure where to go. What I'm really trying to do is figure out what kind of file I can make that will contain all this code and the GUI information that the program will recognize. Any ideas? With thanks, John

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• PHP's fopen is terminally failing

  - by Skittles

  Okay, I have GOT to be missing something totally rudimentary here. I have an extremely simple use of PHP's fopen function, but for some reason, it will not open the file no matter what I do. The odd part about this is that I use fopen in another function in the same script and it's working perfectly. I'm using the fclose in both functions. So, I know it's not a matter of a rogue file handle. I have confirmed the file's path and the existence of the target file also. I'm running the script at the command-line as root, so I know it's not apache that's the cause. And since I am running the script as root, I am fairly confident that permissions are not the issue. So, what on earth am I missing here? function get_file_list() { $file = '/home/site/tmp/return_files_list.txt'; $fp = fopen($file, 'r') or die("Could not open file: /home/site/tmp/return_files_list.txt for reading.\n"); $files_list = array(); while($line = fgets($fp)) { $files_list[] = $line; } fclose($fp); return $files_list; } function num_records_in_file($filename) { $fp = fopen( $filename, 'r' ); # or die("Could not open file: $filename\n"); $counter = 0; if ($fp) { while (!feof( $fp )) { $line = fgets( $fp ); $arr = explode( '|', $line ); if (( ( $arr[0] != 'HDR' && $arr[0] != 'TRL' ) && $arr[0] != '' )) { ++$counter; continue; } } } fclose( $fp ); return $counter; } As requested, here's both functions. The second function is passed an absolute path to the file. That is what I used to confirm that the file is there and that the path is correct.

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• jQuery + form + textinput > Is it possible to display one value in a textinput and submit another?

  - by Ivan Kruchkoff

  I'm working on an application where dates are passed as yyyy-mm-dd but displayed to the client as mm-dd-yyyy (US based client). I'm using a jQuery datepicker for selecting from/to dates in a report and would like to show the dates to the client as mm-dd-yyyy but when the form is submitted, submit as yyyy-mm-dd. Is it possible to display one value in a textinput textbox and have another submitted without needing to hook into onSubmit? I've come up with the following alternatives: Hide the text input for the from and to fields, create dummy fields and make use of the following jQuery date picker functions: altField and altFormat to display the value to the client in their preferred way and deal only with the submitted values which are set through the alt functions. Have an onSubmit javascript call to change the dates from mm-dd-yyyy to dd-mm-yyyy and also change the value=" to change the date to the client's preferred format. Rewrite the app to handle all dates in mm-dd-yyyy and hope the client never has non-US customers that would like their dates in a specific format. Change all dates to dd-Mon-YYYY e.g. 26-May-2010 as all of our client's customers are guaranteed to be English only.

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• ctypes DLL with optional dependencies

  - by pisswillis

  Disclaimer: I'm new to windows programming so some of my assumptions may be wrong. Please correct me if so. I am developing a python wrapper for a C API using ctypes. The API ships with both 64 and 32 DLLs/LIBs. I can succesfully load the DLL using ctypes.WinDLL('TheLibName') and call functions etc etc. However some functions were not doing what they should. Upon further investigation it appears that the 32bit DLL is being used, which is what is causing the unexpected behaviour. I have tried using ctypes.WinDLL('TheLibName64') but the module is not found. I have tried registering the DLL with regsrv32, but it reports there is no entry point (it also reports no entry point when I try and register TheLibName, which is found by WinDLL(). The DLL came with a sample project in Visual Studio (I have 0 experience with VS so again please correct me here) which builds both 32 and 64 bit versions of the sample project. In the .vcsproj file the configurations for the 64 bit version include: AdditionalDependencies="TheLibName64.lib" in the VCLinkerTool section. In windows/system32 there are both TheLibName.dll/.lib, and TheLibName64.dll/.lib. So it seems to me that my problem is now to make the python ctypes DLL loader load these optional dependencies when the DLL is loaded. However I can't find any information on this (perhaps because, as a doze noob, I do not know the correct terminology) in the ctypes documentation. Is there a way to do this in ctypes? Am I going about this in completely the wrong way? Any help or general information about optional DLL dependencies and how they are loaded in windows would be much appreciated. Thanks

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• Link failure with either abnormal memory consumption or LNK1106 in Visual Studio 2005.

  - by Corvin

  Hello, I am trying to build a solution for windows XP in Visual Studio 2005. This solution contains 81 projects (static libs, exe's, dlls) and is being successfully used by our partners. I copied the solution bundle from their repository and tried setting it up on 3 similar machines of people in our group. I was successful on two machines and the solution failed to build on my machine. The build on my machine encountered two problems: During a simple build creation of the biggest static library (about 522Mb in debug mode) would fail with the message "13libd\ui1d.lib : fatal error LNK1106: invalid file or disk full: cannot seek to 0x20101879" Full solution rebuild creates this library, however when it comes to linking the library to main .exe file, devenv.exe spawns link.exe which consumes about 80Mb of physical memory and 250MB of virtual and spawns another link.exe, which does the same. This goes on until the system runs out of memory. On PCs of my colleagues where successful build could be performed, there is only one link.exe process which uses all the memory required for linking (about 500Mb physical). There is a plenty of hard drive space on my machine and the file system is NTFS. All three of our systems are similar - Core2Quad processors, 4Gb of RAM, Windows XP SP3. We are using Visual studio installed from the same source. I tried using a different RAM and CPU, using dedicated graphics adapter to eliminate possibility of video memory sharing influencing the build, putting solution files to different location, using different versions of VS 2005 (Professional, Standard and Team Suite), changing the amount of available virtual memory, running memtest86 and building the project from scratch (i.e. a clean bundle). I have read what MSDN says about LNK1106, none of the cases apply to me except for maybe "out of heap space", however I am not sure how I should fight this. The only idea that I have left is reinstalling the OS, however I am not sure that it would help and I am not sure that my situation wouldn't repeat itself on a different machine. Would anyone have any sort of advice for me? Thanks

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• Make function declarations based on function definitions

  - by Clinton Blackmore

  I've written a .cpp file with a number of functions in it, and now need to declare them in the header file. It occurred to me that I could grep the file for the class name, and get the declarations that way, and it would've worked well enough, too, had the complete function declaration before the definition -- return code, name, and parameters (but not function body) -- been on one line. It seems to me that this is something that would be generally useful, and must've been solved a number of times. I am happy to edit the output and not worried about edge cases; anything that gives me results that are right 95% of the time would be great. So, if, for example, my .cpp file had: i2cstatus_t NXTI2CDevice::writeRegisters( uint8_t start_register, // start of the register range uint8_t bytes_to_write, // number of bytes to write uint8_t* buffer = 0) // optional user-supplied buffer { ... } and a number of other similar functions, getting this back: i2cstatus_t NXTI2CDevice::writeRegisters( uint8_t start_register, // start of the register range uint8_t bytes_to_write, // number of bytes to write uint8_t* buffer = 0) for inclusion in the header file, after a little editing, would be fine. Getting this back: i2cstatus_t writeRegisters( uint8_t start_register, uint8_t bytes_to_write, uint8_t* buffer); or this: i2cstatus_t writeRegisters(uint8_t start_register, uint8_t bytes_to_write, uint8_t* buffer); would be even better.

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• How to pass data to a C++0x lambda function that will run in a different thread?

  - by Dimitri C.

  In our company we've written a library function to call a function asynchronously in a separate thread. It works using a combination of inheritance and template magic. The client code looks as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, &DemoThread::SomeFunction, stringToPassByValue); Since the introduction of lambda functions I'd like to use it in combination with lambda functions. I'd like to write the following client code: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=]() { const std::string someCopy = stringToPassByValue; }); Now, with the Visual C++ 2010 this code doesn't work. What happens is that the stringToPassByValue is not copied. Instead the "capture by value" feature passes the data by reference. The result is that if the function is executed after stringToPassByValue has gone out of scope, the application crashes as its destructor is called already. So I wonder: is it possible to pass data to a lambda function as a copy? Note: One possible solution would be to modify our framework to pass the data in the lambda parameter declaration list, as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=](const std::string stringPassedByValue) { const std::string someCopy = stringPassedByValue; } , stringToPassByValue); However, this solution is so verbose that our original function pointer solution is both shorter and easier to read. Update: The full implementation of AsyncCall is too big to post here. In short, what happens is that the AsyncCall template function instantiates a template class holding the lambda function. This class is derived from a base class that contains a virtual Execute() function, and upon an AsyncCall() call, the function call class is put on a call queue. A different thread then executes the queued calls by calling the virtual Execute() function, which is polymorphically dispatched to the template class which then executes the lambda function.

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• What's the SQL function for timestamp manipulation?

  - by Eric Leroy

  I'm new to SQL and the time functions are different than mySQL so I'm having a terrible time finding a good site reference with USEFUL timestamp queries. I'm not able to locate the correct way of doing this query in SQL: Id Timestamp ----------------------------------- 1145744 2012-10-10 18:15:11.500 1145743 2012-10-10 18:15:11.313 1145742 2012-10-10 18:15:11.313 1145741 2012-10-10 18:15:11.253 1145740 2012-10-10 18:15:11.190 1145739 2012-10-10 18:15:11.190 1145738 2012-10-10 18:15:11.127 1145737 2012-10-10 18:15:11.067 1145736 2012-10-10 18:15:11.063 1145735 2012-10-10 18:15:10.940 1145734 2012-10-10 18:15:10.817 SELECT * from table WHERE Timestamp ... RANGE I need the range of 2 timestamps so I can select rows by the following parameters: second range minute range hour range day range week range month range year range Is there one function to put in 2 timestamps and get the range? or is this a mix of functions I need? Any good site references would be greatly appriceated. MSDN site isn't helping me isolate the proper way of doing this. I've been searching for about an hour trying to get the last day from 1:30PM to 1:30PM today.

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• Analyzing an IronPython Scope

  - by Vercinegetorix

  I'm trying to write C# code with an embedded IronPython script. Then want to analyze the contents of the script, i.e. list all variables, functions, class and their members/methods. There's an easy way to start, assuming I've got a scope defined and code executed in it already: dynamic variables=pyScope.GetVariables(); foreach (string v in variables) { dynamic dynamicV=pyScope.GetVariable(); /*seems to return everything. variables, functions, classes, instances of classes*/ } But how do I figure out what the type of a variable is? For the following python 'objects', dynamicV.GetType() will return different values: x=5 --system.Int32 y="asdf" --system.String def func():... --IronPython.Runtime.PythonFunction z=class() -- IronPython.Runtime.Types.OldInstance, how can I identify what the actual python class is? class NewClass -- throws an error, GetType() is unavailable. This is almost what I'm looking for. I could capture the exception thrown when unavailable and assume it's a class declaration, but that seems unclean. Is there a better approach? To discover the members/methods of a class it looks like I can use: ObjectOperations op = pyEngine.Operations; object instance = op.Call("className"); foreach (string j in op.GetMemberNames("className")) { object member=op.GetMember(instance, j); Console.WriteLine(member.GetType()); /*once again, GetType() provides some info about the type of the member, but returns null sometimes*/ } Also, how do I get the parameters to a method? Thanks!

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• Freetype2 (error-)return value documentation

  - by Awaki

  In short, I'm looking for documentation that would limit the error situations to check for after a Freetype library function failed, much like the OpenGL and Win32 APIs document the error codes generated by their respective functions. I can't seem to find such documentation though, so I was wondering how to best handle translation of Freetype errors to typed exceptions. Background: I am currently in the process of implementing font-rendering capability (using Freetype) for my GUI framework, which makes strong use of typed exceptions to indicate error situations. However, the Freetype docs seem to completely omit what errors can be expected from what functions. That, if such documentation does indeed not exist, would basically leave me with two options: either guessing which errors make sense for a certain Freetype function (obviously prone to mistakes on my part), or considering every error code for translation into appropriate exceptions (less verbose since I would have to write the translation only once). Performance isn't really critical in the code that calls the Freetype library, so even the latter option would probably be acceptable, but surely there must be some kind of documentation on which library calls may return what Freetype error? Is there any such documentation which I just somehow managed to not find? Should I go the route of generically expecting every error code for translation? Or are there other ways to approach this problem? By the way, I wanted to avoid introducing some kind of generic FreetypeException (containing a description of the Freetype error) since I intended to completely hide what libraries I'm using (not from a legal point-of-view, mind you), but I guess I can be convinced to do this anyway if the consensus is that it would be the best option. I don't think it matters for this question, but I'm writing in C++.

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• Inline function v. Macro in C -- What's the Overhead (Memory/Speed)?

  - by Jason R. Mick

  I searched Stack Overflow for the pros/cons of function-like macros v. inline functions. I found the following discussion: Pros and Cons of Different macro function / inline methods in C ...but it didn't answer my primary burning question. Namely, what is the overhead in c of using a macro function (with variables, possibly other function calls) v. an inline function, in terms of memory usage and execution speed? Are there any compiler-dependent differences in overhead? I have both icc and gcc at my disposal. My code snippet I'm modularizing is: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = AttractiveTerm * AttractiveTerm; EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); My reason for turning it into an inline function/macro is so I can drop it into a c file and then conditionally compile other similar, but slightly different functions/macros. e.g.: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = pow(SigmaSquared/RadialDistanceSquared,9); EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); (note the difference in the second line...) This function is a central one to my code and gets called thousands of times per step in my program and my program performs millions of steps. Thus I want to have the LEAST overhead possible, hence why I'm wasting time worrying about the overhead of inlining v. transforming the code into a macro. Based on the prior discussion I already realize other pros/cons (type independence and resulting errors from that) of macros... but what I want to know most, and don't currently know is the PERFORMANCE. I know some of you C veterans will have some great insight for me!!

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• Inheritance of TCollectionItem

  - by JamesB

  I'm planning to have collection of items stored in a TCollection. Each item will derive from TBaseItem which in turn derives from TCollectionItem, With this in mind the Collection will return TBaseItem when an item is requested. Now each TBaseItem will have a Calculate function, in the the TBaseItem this will just return an internal variable, but in each of the derivations of TBaseItem the Calculate function requires a different set of parameters. The Collection will have a Calculate All function which iterates through the collection items and calls each Calculate function, obviously it would need to pass the correct parameters to each function I can think of three ways of doing this: Create a virtual/abstract method for each calculate function in the base class and override it in the derrived class, This would mean no type casting was required when using the object but it would also mean I have to create lots of virtual methods and have a large if...else statement detecting the type and calling the correct "calculate" method, it also means that calling the calculate method is prone to error as you would have to know when writing the code which one to call for which type with the correct parameters to avoid an Error/EAbstractError. Create a record structure with all the possible parameters in and use this as the parameter for the "calculate" function. This has the added benefit of passing this to the "calculate all" function as it can contain all the parameters required and avoid a potentially very long parameter list. Just type casting the TBaseItem to access the correct calculate method. This would tidy up the TBaseItem quite alot compared to the first method. What would be the best way to handle this collection?

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• ASP.NET MVC4: How do I keep from having multiple identical results in my lookup tables

  - by sehummel

  I'm new to ASP.NET so this may be an easy question. I'm seeding my database with several rows of dummy data. Here is one of my rows: new Software { Title = "Microsoft Office", Version = "2012", SerialNumber = "12346231434543", Platform = "PC", Notes = "Macs really rock!", PurchaseDate = "2011-12-04", Suite = true, SubscriptionEndDate = null, SeatCount = 0, SoftwareTypes = new List<SoftwareType> { new SoftwareType { Type="Suite" }}, Locations = new List<Location> { new Location { LocationName = "Paradise" }}, Publishers = new List<SoftwarePublisher> { new SoftwarePublisher { Publisher = "Microsoft" }}} But when I do this, a new row is created for each location, with the LocationName being set in each row like this. We only have two locations. How do I get it to create a LocationID property for the Software class and in my Locations class. Here is my Location class: public class Location { public int Id { get; set; } [Required] [StringLength(20)] public string LocationName { get; set; } public virtual Software Software { get; set; } } I have this line in my Software class to reference this table: public virtual List<Location> Locations { get; set; } Again, what I want when I am done is a Locations table with two entries, and a LocationID field in my Software table. How do I do this?

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• C++ linker unresolved external symbol (again;) from other source file *.obj file. (VC++ express)

  - by bua

  Hi there, I'm back to C/C++ after some break. I've a following problem: I've a solution where I've several projects (compilable and linkable). Now I need to add another project to this solution which depends on some sources from other projects. My new project compiles without any problems (I've added "existing sources" to my project). the error: 1>Linking... 1>LicenceManager.obj : error LNK2019: unresolved external symbol "int __cdecl saveLic(char *,struct Auth *)" (?saveLic@@YAHPADPAUAuth@@@Z) referenced in function "public: void __thiscall LicenceManager::generateLicence(int,char *)" (?generateLicence@LicenceManager@@QAEXHPAD@Z) 1>LicenceManager.obj : error LNK2019: unresolved external symbol "void __cdecl getSysInfo(struct Auth *)" (?getSysInfo@@YAXPAUAuth@@@Z) referenced in function "public: void __thiscall LicenceManager::generateLicence(int,char *)" (?generateLicence@LicenceManager@@QAEXHPAD@Z) Functions saveLic, and getSysInfo are defined in files which I've added to my new project from existing ones. There is object file created during compilation with those functions in target dir, but my LicenceManager class doesn't want to link. I use some extern "C" , and #pragma pack somewhere, but no more fancy stuff. I think every directory, lib and other necessary dependencies are visible in settings for this project. Thanks for any advice.

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• C# array of objects - conditional validation

  - by fishdump

  Sorry about the vague title! I have an class with a number of member variables (system, zone, site, ...) public sealed class Cello { public String Company; public String Zone; public String System; public String Site; public String Facility; public String Process; //... } I have an array of objects of this class. private Cello[] m_cellos = null; // ... I need to know whether the array contains objects with the same site but different systems, zones or companies since such a situation would be illegal. I have various other checks to make but they are all along similar lines. The Array class has a number of functions that look promising but I am not very up on defining 'key selector' functions and things like that. Any suggestions or pointers would be greatly appreciated. --- Alistair.

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• Who needs singletons?

  - by sexyprout

  Imagine you access your MySQL database via PDO. You got some functions, and in these functions, you need to access the database. The first thing I thought of is global, like: $db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'root', 'pwd'); function some_function() { global $db; $db->query('...'); } But it's considered as a bad practice. So, after a little search, I ended up with the Singleton pattern, which "applies to situations in which there needs to be a single instance of a class." According to the example of the manual, we should do this: class Database { private static $instance, $db; private function __construct(){} static function singleton() { if(!isset(self::$instance)) self::$instance = new __CLASS__; return self:$instance; } function get() { if(!isset(self::$db)) self::$db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'user', 'pwd') return self::$db; } } function some_function() { $db = Database::singleton(); $db->get()->query('...'); } some_function(); But I just can't understand why you need that big class when you can do it merely with: class Database { private static $db; private function __construct(){} static function get() { if(!isset(self::$rand)) self::$db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'user', 'pwd'); return self::$db; } } function some_function() { Database::get()->query('...'); } some_function(); This last one works perfectly and I don't need to worry about $db anymore. But maybe I'm forgetting something. So, who's wrong, who's right?

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