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  • How do you use stl's functions like for_each?

    - by thomas-gies
    I started using stl containers because they came in very handy when I needed functionality of a list, set and map and had nothing else available in my programming environment. I did not care much about the ideas behind it. STL documentations were only interesting up to the point where it came to functions, etc. Then I skipped reading and just used the containers. But yesterday, still being relaxed from my holidays, I just gave it a try and wanted to go a bit more the stl way. So I used the transform function (can I have a little bit of applause for me, thank you). From an academic point of view it really looked interesting and it worked. But the thing that boroughs me is that if you intensify the use of those functions, you need 10ks of helper classes for mostly everything you want to do in your code. The hole logic of the program is sliced in tiny pieces. This slicing is not the result of god coding habits. It's just a technical need. Something, that makes my life probably harder not easier. And I learned the hard way, that you should always choose the simplest approach that solves the problem at hand. And I can't see what, for example, the for_each function is doing for me that justifies the use of a helper class over several simple lines of code that sit inside a normal loop so that everybody can see what is going on. I would like to know, what you are thinking about my concerns? Did you see it like I do when you started working this way and have changed your mind when you got used to it? Are there benefits that I overlooked? Or do you just ignore this stuff as I did (and will go an doing it, probably). Thanks. PS: I know that there is a real for_each loop in boost. But I ignore it here since it is just a convenient way for my usual loops with iterators I guess.

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  • Adding functions to Java class libraries

    - by Eric
    I'm using a Java class library that is in many ways incomplete: there are many classes that I feel ought to have additional member functions built in. However, I am unsure of the best practice of adding these member functions. Lets call the insufficient base class A. class A { public A(/*long arbitrary arguments*/) { //... } public A(/*long even more arbitrary arguments*/) { //... } public int func() { return 1; } } Ideally, I would like to add a function to A. However, I can't do that. My choice is between: class B extends A { //Implement ALL of A's constructors here public int reallyUsefulFunction() { return func()+1; } } and class AddedFuncs { public int reallyUsefulFunction(A a) { return a.func()+1; } } The way I see it, they both have advantages and disadvantages. The first choice gives a cleaner syntax than the second, and is more logical, but has problems: Let's say I have a third class, C, within the class library. class C { public A func() { return new A(/*...*/); } } As I see it, there is no easy way of doing this: C c; int useful = c.func().reallyUsefulFunction(); as the type returned by C.func() is an A, not a B, and you can't down-cast. So what is the best way of adding a member function to a read-only library class?

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  • Ubuntu virtual memory caches suck up memory

    - by Tom
    Hey all, I've got an Ubuntu 9.10 64-bit server that seems to use up all available memory. According to my munin graphs, almost all of the memory used up is in the swap cache, cache, and slab cache. (I take this to mean virtual memory caches, am I right in assuming this?) Once memory usage approaches 100%, some (although not all) system services such as SSH become sluggish and unresponsive. After rebooting the system, performance and memory usage become normal for a time. Some interesting tidbits: The system runs Apache 2, MySQL, Munin, and sshd. The memory usage spikes happen at the same time every night (at 10 PM sharp.) There appears to be nothing in the crontab for any of the users, and nothing in /etc/cron.d/* out of the ordinary, let alone something that would occur at 10 PM. My question is, how do I figure out what is causing the memory suckage? I've tried the usual utilities (e.g. ps, top, etc) but I can't seem to find anything unusual. Any ideas? Thanks in advance!

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  • URL Rewriting on GoDaddy Virtual Server

    - by Aristotle
    I migrated a Kohana2 application from a shared-hosting environment over to a virtual dedicated server. After this migration, I can't seem to get my .htaccess file working again. I apologize up front, but over the years I have never experienced so much frustration with anything else as I do with the dreaded .htaccess file. Presently I have my project installed immediately within a directory in my public folder: /var/html/www/info.php (general information about server) /var/html/www/logo.jpg (some flat file) /var/html/www/somesite.com/[kohana site exists here] So my .htaccess file is within that directory, and has the following contents: # Turn on URL rewriting RewriteEngine On # Installation directory RewriteBase /somesite.com/ # Protect application and system files from being viewed # This is only necessary when these files are inside the webserver document root RewriteRule ^(application|modules|system) - [R=404,L] # Allow any files or directories that exist to be displayed directly RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d # Rewrite all other URLs to index.php/URL RewriteRule .* index.php?kohana_uri=$0 [PT,QSA,L] # Alternativly, if the rewrite rule above does not work try this instead: #RewriteRule .* index.php?kohana_uri=$0 [PT,QSA,L] This doesn't work. The initial controller is loaded, since index.php is called up implicitly when nothing else is in the url. But if I try to load up some other non-default controller, the site fails. If I place the index.php back within the url, the call to other controllers works just fine. I'm really at my wits end, and would appreciate some direction here.

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  • VMWare Fusion: "No Permission to access this virtual machine"

    - by Craig Walker
    I had a VMWare Fusion VM backed up on my home network file server (Ubuntu). I wanted to run it again, so I copied it back to my Macbook. When I tried to launch it in VMWare, I got an error message: No permission to access this virtual machine. Configuration file: /Users/craig/WinXP Clean + Scanner.vmwarevm/WinXP Pro Test.vmx The permissions look fine to me: The bundle directory is 777 The bundle files (including the listed .vmx) are all 666 User is craig (my current user); group is staff. I changed the group to wheel at the suggestion of this page, but that didn't help. Finder shows read & write for craig, staff, and everyone on the bundle directory The bundle dir is also not locked Finder also shows rw and unlocked for the .vmx file The parent directory is also rw & unlocked Disk Utility permissions check doesn't show any problems with any of the associated files It sure looks like I should have wide open access to run this VM; why is Fusion complaining?

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  • Physical-to-virtual for personal use

    - by Journeyman Geek
    One of my current projects involves reducing the number of old computers lying around. So far, the office systems have been downsized from 5 to 2. One system which had no data on it was dumped entirely, while three other identical boxes were consolidated into to one (I swap hard drives as needed and they just work(tm)). I want to make further cuts. The physical systems in question all run windows xp sp3, and were old Pentium 4s with 256 MB of RAM. Currently, I have got a VirtualBox running on another system. My intention is to migrate all services to that. We can assume that disk space and RAM on the host is not an issue. I'd rather not go with a client-server physical-to-virtual (P2V) method like what VirtualBox uses now. I have a few specific concerns as well - specifically whether I'd need to reactivate or sysprep for dissimilar hardware first. An offline tool for imaging (Windows or Linux) would not be an issue since the drives could be mounted onto another system I have anyway or I could use a LiveCD. What would be my options for P2V conversion, and what would I need to keep in mind when doing this?

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  • No LPT port in Windows 7 virtual machines

    - by KeyboardMonkey
    Windows 7 has MS virtual PC integrated, the VM settings don't give a parallel LPT port mapping to the physical machine. Where did it go? Has anyone else noticed this, and found a solution? Update: After much digging, I found the one and only reference to this issue, on the VPC Blog: "Parallel port devices are not supported, as they are relatively rare today." -More details- It's a XP VM I've been using since VPC 2007 days, which did have this functionality. This is to configure barcode printers via the LPT port. Since the (new) MS VM can't map to my physical LPT port, I'm having a hard time configuring printers. My physical ports are enabled in the BIOS. It has worked the past 3 years, before switching to Win 7. Any help is appreciated. This screen shot of the VM settings shows COM ports, but LPT is no more In contrast, here is a screen shot of VPC 2007 (before it got integrated into Win 7). Notice how it has LPT support

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  • Virtual machines with failover setup

    - by kimmmo
    We have three servers and our plan is to run a number of virtual machines on them in such manner, that if one of the nodes blow up, we can either quickly or seamlessly get a spare running on another node. In addition to the normal networking, they're interconnected via dual 10Gbit NIC's, so networked raid/mirroring shouldn't be a problem. The guest VM's are mostly going to be running text mode linux, but of course it wouldn't hurt to be able to spin up a non-mission critical windows guest for running Visual Studio or checking IE compatibility of a web app. We've spent some time trying to get some magical cloud setup running using Stackops and Crowbar but it started to look like they were offering way too much and were too complicated for our needs. The next candidate, I think, is Ubuntu 11.04 server + KVM + Ganeti + Drbd, unless you can come up with a suggestion for a better solution that we have missed. Requirements: Installation should be simple or at least understandable without being in the dev team A browser interface for creating and managing VM's is a nice bonus Single node's hardware failure should cause minimal downtime for VM's that were running on that node Adding more nodes should be possible without shutting down the VM's.

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  • Authenticate domain-user credentials on unjoined virtual machine?

    - by bwerks
    Hi all, This question may sound silly, and perhaps a bit insane, but--is there any way to run a process on a machine not joined to a domain using credentials from a user in that domain? In my case, I'm running virtual machines installed with release binaries from our build process, as well as Visual Studio. Visual Studio is there to debug our release binaries, however it's being executed with vm-local user credentials. This means that it can't authenticate to our TFS deployment when executing "tf.exe view" to utilize our Source Server for debugging. Team Explorer manages to authenticate to TFS using a UI prompt, however I suspect that it's because we supply it with the TFS deployment's URI, and it's designed to display a prompt to facilitate workgroup scenarios; i.e. it's not like we're getting it for free. My instincts tell me the only way to authenticate on this vm is to join it or somehow form a one-way trust or something, but is there an easier way? For automation we're going to want to script this eventually, but I'm first surveying the feasibility of the thing.

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  • Missing access log for virtual host on Plesk

    - by Cummander Checkov
    For some reason i don't understand, after creating a new virtual host / domain in Plesk a few months back, i cannot seem to find the access log. I noticed this when running /usr/local/psa/admin/sbin/statistics The host in question is being scanned Main HTML page is 'awstats.<hostname_masked>-http.html'. Create/Update database for config "/opt/psa/etc/awstats/awstats.<hostname_masked>.com-https.conf" by AWStats version 6.95 (build 1.943) From data in log file "-"... Phase 1 : First bypass old records, searching new record... Searching new records from beginning of log file... Jumped lines in file: 0 Parsed lines in file: 0 Found 0 dropped records, Found 0 corrupted records, Found 0 old records, Found 0 new qualified records. So basically no access logs have been parsed/found. I then went on to check if i could find the log myself. I looked in /var/www/vhosts/<hostname_masked>.com/statistics/logs but all i find is error_log Does anybody know what is wrong here and perhaps how i could fix this? Note: in the <hostname_masked>.com/conf/ folder i keep a custom vhost.conf file, which however contains only some rewrite conditions plus a directory statement that contains php_admin_flag and php_admin_value settings. None of them are related to logging though.

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  • backup an existing linux server to a virtualbox virtual machine

    - by user146526
    I have some servers and VPSs to many companies across the world. I want to back them up locally. I have some backup solutions enabled to remote hosts, but I want to have a local backup on a computer at home. What I am thinking is: 1) Create a virtualbox virtual machine, install the same version linux as the server. 2) Use rsync to backup the server to the local virtualbox machine. (something like rsync -av --delete --progress --exclude '/dev/' --exclude '/proc/' root@server_ip:// / ) 3) Repeat the command every few days update files. 4) In case of a hard disk failure, or any other bad event, reverse the rsync command and get the files back and continue my bussiness. I tried it with 2 openvz VPS, the one was a backup of the other. I also tried to transfer normal linux server host to openvz machine and it worked great. That way looks pretty clean and easy to me, this is the kind of solution I am looking for. However I need to be sure that this will work if I am going to do it. The question is, will that work ok ? Does anyone see any problem with that ? Do you have any other suggestions ? Thanks

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  • Dedicated Mouse and Keyboard on Virtual Box VM

    - by Myersguy
    To all super users, Currently I am trying to run virtual box on my second monitor, with a dedicated mouse and keyboard. However, doing so has not proven easy. There has been times where the mouse works, but not the keyboard, vice versa, or nothing works at all. The biggest problem I am running into is this: When enabling the USB mouse and keyboard from the VM, I get an error: 'USB Device is busy with a previous request.' The only thing that is using second mouse and keyboard, however, is Windows. The other error I have received stated that the VM was unable to create a proxy for the device. Additionally, the VM occasionally will disable the secondary keyboard entirely, requiring me to unplug and replug it into my PC to re-enable it again. Keyboard auto-capture is disabled, and while a solution I was reading online stated to turn off mouse integration, that option is grayed out on my machine. Any help would be appreciated. Thanks. /firstquestion.

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  • How to connect 2 virtual hosts running on the same machine?

    - by Gabrielle
    I have 2 virtual hosts running on my Windows XP laptop. One is Ubuntu running inside vmware player. The other is MS virtual PC (so I can test with IE6 ). The Ubuntu virtual host is running my web application with apache. I can point my browser on my laptop at the Ubuntu IP and view my web app. I read this post http://stackoverflow.com/questions/197792/how-to-connect-to-host-machine-from-within-virtual-pc-image and was able to get my Virtual PC to ping my physical machine using the loopback adapter. But I'm stuck on getting my Virtual PC to see my web application running in the Ubuntu vmware player host. I appreciate any suggestions.

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  • Getting Drag and Drop to Work in Virtual PC 2007 on Windows 7.

    - by Kryten
    Hi, I have Virtual PC 2007 installed on my Windows 7 machine. Before anyone asks, I have installed VPC 2007 because my machine does not support the new Virtual PC for Windows 7. Everythings working fine, except for the drag and drop file feature. On my old Windows XP machine the drag and drop feature works fine, but on Windows 7, nothing happens. I just get the "no drop" cursor. I HAVE installed Virtual Machine Additions and have run Virtual PC under XP Compatability, but still nothing. The Virtual Machines I have tried draging and dropping files onto on are: Windows 2000 Windows XP Windows 98 and as I said they all have Virtual Machine Additions on them. Whats going on? How can I get the drag and drop feature working? I did see this question, but it still doesn't answer my question.

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  • Calling methods or functions with Jquery

    - by Ross
    So I can call a php page using jquery $.ajax({ type: "GET", url: "refresh_news_image.php", data: "name=" + name, success: function(html) { alert(html) $('div.imageHolder').html(html); } }); However this getting a bit messy, I have a few .php files that only really preform very simple tasks. If I want to call a method $images-refresh_image(); is this possible. Failing that I could just create a big file with lots of functions in it? Thanks, Ross

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  • self join- how to use the aggregate functions

    - by Ranjana
    self join- how to use the aggregate functions select a.tablename, b.TableName,b.UserName from Employee a inner join Employee b on a.ColumnValue=b.ColumnValue and and a.TableName <> b.TableName and a.UserName=b.UserName and also to check whether the same user has count of records i.e Employee a = count of records of Employee b. how to add count function over here

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  • Overload Anonymous Functions

    - by Nissan Fan
    Still wrapping my head around Delegates and I'm curious: Is it possible to overload anonymous functions? Such that: delegate void Output(string x, int y); Supports: Output show = (x, y) => Console.WriteLine("{0}: {1}", x.ToString(), y.ToString()); And: delegate void Output(string x, string y); Allowing: show( "ABC", "EFG" ); And: show( "ABC", 123 );

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  • user generated / user specific functions

    - by pedalpete
    I'm looking for the most elegant and secure method to do the following. I have a calendar, and groups of users. Users can add events to specific days on the calendar, and specify how long each event lasts for. I've had a few requests from users to add the ability for them to define that events of a specific length include a break, of a certain amount of time, or require that a specific amount of time be left between events. For example, if event is 2 hours, include a 20min break. for each event, require 30 minutes before start of next event. The same group that has asked for an event of 2 hours to include a 20 min break, could also require that an event 3 hours include a 30 minute break. In the end, what the users are trying to get is an elapsed time excluding breaks calculated for them. Currently I provide them a total elapsed time, but they are looking for a running time. However, each of these requests is different for each group. Where one group may want a 30 minute break during a 2 hour event, and another may want only 10 minutes for each 3 hour event. I was kinda thinking I could write the functions into a php file per group, and then include that file and do the calculations via php and then return a calculated total to the user, but something about that doesn't sit right with me. Another option is to output the groups functions to javascript, and have it run client-side, as I'm already returning the duration of the event, but where the user is part of more than one group with different rules, this seems like it could get rather messy. I currently store the start and end time in the database, but no 'durations', and I don't think I should be storing the calculated totals in the db, because if a group decides to change their calculations, I'd need to change it throughout the db. Is there a better way of doing this? I would just store the variables in mysql, but I don't see how I can then say to mysql to calculate based on those variables. I'm REALLY lost here. Any suggestions? I'm hoping somebody has done something similar and can provide some insight into the best direction. If it helps, my table contains eventid, user, group, startDate, startTime, endDate, endTime, type The json for the event which I return to the user is {"eventid":"'.$eventId.'", "user":"'.$userId.'","group":"'.$groupId.'","type":"'.$type.'","startDate":".$startDate.'","startTime":"'.$startTime.'","endDate":"'.$endDate.'","endTime":"'.$endTime.'","durationLength":"'.$duration.'", "durationHrs":"'.$durationHrs.'"} where for example, duration length is 2.5 and duration hours is 2:30.

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  • JavaScript Collection of one-line Useful Functions

    - by Wilq32
    This is a question to put as many interesting and useful JavaScript functions written in one line as we can. I made this question because I'm curious how many people around like the art of one-Line programming in JavaScript, and I want to see their progress in action. Put variations of each code inside comments.

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  • Using multiple aggregate functions in an algebraic expression in (ANSI) SQL statement

    - by morpheous
    I have the following aggregate functions (AGG FUNCs): foo(), foobar(), fredstats(), barneystats(). I want to know if I can use multiple AGG FUNCs in an algebraic expression. This may seem a strange/simplistic question for seasoned SQL developers - however, the but the reason I ask is that so far, all AGG FUNCs examples I have seen are of the simplistic variety e.g. max(salary) < 100, rather than using the AGG FUNCs in an expression which involves using multiple AGG FUNCs in an expression (like agg_func1() agg_func2()). The information below should help clarify further. Given tables with the following schemas: CREATE TABLE item (id int, length float, weight float); CREATE TABLE item_info (item_id, name varchar(32)); # Is it legal (ANSI) SQL to write queries of this format ? SELECT id, name, foo, foobar, fredstats FROM A, B (SELECT id, foo(123) as foo, foobar('red') as foobar, fredstats('weight') as fredstats FROM item GROUP BY id HAVING [ALGEBRAIC EXPRESSION] ORDER BY id AS A), item_info AS B WHERE item.id = B.id Where: ALGEBRAIC EXPRESSION is the type of expression that can be used in a WHERE clause - for example: ((foo(x) < foobar(y)) AND foobar(y) IN (1,2,3)) OR (fredstats(x) <> 0)) I am using PostgreSQL as the db, but I would prefer to use ANSI SQL wherever possible. Assuming it is legal to include AGG FUNCS in the way I have done above, I'd like to know: Is there a more efficient way to write the above query ? Is there any way I can speed up the query in terms of a judicious choice of indexes on the tables item and item_info ? Is there a performance hit of using AGG FUNCs in an algebraic expression like I am (i.e. an expression involving the output of aggregate functions rather than constants? Can the expression also include 'scaled' AGG FUNC? (for example: 2*foo(123) < -3*foobar(456) ) - will scaling (i.e. multiplying an AGG FUNC by a number have an effect on performance?) How can I write the query above using INNER JOINS instead?

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