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  • Apache cyclic redirection problem

    - by slicedlime
    I have an extremely weird problem with one of my sites. I run a number of blogs off a single apache2 server with a shared wordpress install. Each site has a www.domain.com main domain, but a ServerAlias of domain.com. This works fine for all the blogs except one, which instead of redirecting to www.domain.com redirects to domain.com, causing a cyclic redirection. The configuration for each host looks like this: <VirtualHost *:80> ServerName www.domain.com ServerAlias domain.com DocumentRoot "/home/www/www.domain.com" <Directory "/home/www/www.domain.com"> Options MultiViews Indexes Includes FollowSymLinks ExecCGI AllowOverride All Order allow,deny Allow from all </Directory> </VirtualHost> As this didn't work, I tried a mod_rewrite rule for it, which still didn't redirect correctly. The weird thing here is that if i rewrite it to redirect to any other domain it will redirect correctly, even to another subdomain. So a rewrite rule for domain.com that redirects to foo.domain.com works, but not to www.domain.com. In the same way, trying to redirec to www.domain.com/foo/ ends me up with a redirection to domain.com/foo/. Even weirder, I tried setting up domain.com as a completely separate virtual host, and ran this php test script as index.php on it: <?php header('Location: http://www.domain.com/' . $_SERVER["request_uri"]); ?> Hitting domain.com still redirects to domain.com! Checking out the headers sent to the server verifies that I get exactly the redirect URL I wanted, except with the "www." stripped. The same script works like a charm if I replace www. with foo or redirect to any other domain. This has now foiled me for a long time. I've diffed the vhosts configs for a working domain and the faulty one, and the only difference is the domain name itself. I've diffed the .htaccess files for both sites, and the only difference is a path related to the sharing of wordpress installation for the blogs: php_value include_path ".:/home/www/www.domain.com/local/:/home/www/www.domain.com/" I searched through everything in /etc (including apache conf) for the domain name of the faulty host and found nothing weird, searched through everything in /etc for one of the working ones to make sure it didn't differ, I even went so far to check on the DNS setup of two domains to make sure there wasn't anything strange going on. Here's the response for the faulty one: user@localhost dir $ wget -S domain.com --2010-03-20 21:47:24-- http://domain.com/ Resolving domain.com... x.x.x.x Connecting to domain.com|x.x.x.x|:80... connected. HTTP request sent, awaiting response... HTTP/1.1 301 Moved Permanently Via: 1.1 ISA Connection: Keep-Alive Proxy-Connection: Keep-Alive Content-Length: 0 Date: Sat, 20 Mar 2010 20:47:24 GMT Location: http://domain.com/ Content-Type: text/html; charset=UTF-8 Server: Apache X-Powered-By: PHP/5.2.10-pl0-gentoo X-Pingback: http://domain.com/xmlrpc.php Keep-Alive: timeout=15, max=100 Location: http://domain.com/ [following] And a working one: user@localhost dir $ wget -S domain.com --2010-03-20 21:51:33-- http://domain.com/ Resolving domain.com... x.x.x.x Connecting to domain.com|x.x.x.x|:80... connected. HTTP request sent, awaiting response... HTTP/1.1 301 Moved Permanently Via: 1.1 ISA Connection: Keep-Alive Proxy-Connection: Keep-Alive Content-Length: 0 Date: Sat, 20 Mar 2010 20:51:33 GMT Location: http://www.domain.com/ Content-Type: text/html; charset=UTF-8 Server: Apache X-Powered-By: PHP/5.2.10-pl0-gentoo X-Pingback: http://www.domain.com/xmlrpc.php Keep-Alive: timeout=15, max=100 Location: http://www.domain.com/ [following] I'm stumped. I've had this problem for a long time, and I feel like I've tried everything. I can't see why the different domains would act differently under the same installation with the same settings. Help :(

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  • DNS Server Behind NAT

    - by Bryan
    I've got a Bind 9 DNS server sitting behind a NAT firewall, assume the Internet facing IP is 1.2.3.4 There are no restrictions on outgoing traffic, and port 53 (TCP/UDP) is forwarded from 1.2.3.4 to the internal DNS server (10.0.0.1). There are no IP Tables rules on either the VPS or the internal Bind 9 server. From a remote Linux VPS located elsewhere on the internet, nslookup works fine # nslookup foo.example.com 1.2.3.4 Server: 1.2.3.4 Address: 1.2.3.4#53 Name: foo.example.com Addresss: 9.9.9.9 However, when using the host command on the remote VPS, I receive the following output: # host foo.example.com 1.2.3.4 ;; reply from unexpected source: 1.2.3.4#13731, expected 1.2.3.4#53 ;; reply from unexpected source: 1.2.3.4#13731, expected 1.2.3.4#53 ;; connection timed out; no servers could be reached. From the VPS, I can establish a connection (using telnet) to 1.2.3.4:53 From the internal DNS server (10.0.0.1), the host command appears to be fine: # host foo.example.com 127.0.0.1 Using domain server: Name: 127.0.0.1 Address: 127.0.0.1#53 Aliases: foo.example.com has address 9.9.9.9 Any suggestions as to why the host command on my VPS is complaining about the reply coming back from another port, and what can I do to fix this? Further info: From a windows host external to the network >nslookup foo.example.com 1.2.3.4 DNS request timeout timeout was 2 seconds Server: UnKnown Address: 1.2.3.4 DNS request timed out. timeout was 2 seconds DNS request timed out. timeout was 2 seconds DNS request timed out. timeout was 2 seconds DNS request timed out. timeout was 2 seconds *** Request to UnKnown timed-out This is a default install of bind from Ubuntu 12.04 LTS, with around 11 zones configured. $ named -v BIND 9.8.1-P1 TCP Dump (filtered) from internal DNS server 20:36:29.175701 IP pc.external.com.57226 > dns.example.com.domain: 1+ PTR? 4.3.2.1.in-addr.arpa. (45) 20:36:29.175948 IP dns.example.com.domain > pc.external.com.57226: 1 Refused- 0/0/0 (45) 20:36:31.179786 IP pc.external.com.57227 > dns.example.com.domain: 2+[|domain] 20:36:31.179960 IP dns.example.com.domain > pc.external.com.57227: 2 Refused-[|domain] 20:36:33.180653 IP pc.external.com.57228 > dns.example.com.domain: 3+[|domain] 20:36:33.180906 IP dns.example.com.domain > pc.external.com.57228: 3 Refused-[|domain] 20:36:35.185182 IP pc.external.com.57229 > dns.example.com.domain: 4+ A? foo.example.com. (45) 20:36:35.185362 IP dns.example.com.domain > pc.external.com.57229: 4*- 1/1/1 (95) 20:36:37.182844 IP pc.external.com.57230 > dns.example.com.domain: 5+ AAAA? foo.example.com. (45) 20:36:37.182991 IP dns.example.com.domain > pc.external.com.57230: 5*- 0/1/0 (119) TCP Dump from client during query 21:24:52.054374 IP pc.external.com.43845 > dns.example.com.53: 6142+ A? foo.example.com. (45) 21:24:52.104694 IP dns.example.com.29242 > pc.external.com.43845: UDP, length 95

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  • warning: dict_ldap_lookup: Search error 1: Operations error

    - by drecute
    Please I need help with ldap search filter to use to retrieve the user email information from ldap. I'm running postfix_ldap of Ubuntu server 12.04. Everything seems to work fine, except getting the values returned from the search. Version 1 server_host = ldap://samba.example.com search_base = dc=company, dc=example, dc=com query_filter = mail=%s bind = no domain = example.com Version 2 server_host = ldap://samba.example.com search_base = dc=company, dc=example, dc=com query_filter = mail=%s bind_dn = cn=Users,dc=company,dc=example,dc=com domain = example.com mail logs Nov 26 11:13:26 mail postfix/smtpd[19662]: match_string: example.com ~? example.com Nov 26 11:13:26 mail postfix/smtpd[19662]: dict_ldap_lookup: No existing connection for LDAP source /etc/postfix/ldap-aliases.cf, reopening Nov 26 11:13:26 mail postfix/smtpd[19662]: dict_ldap_connect: Connecting to server ldap://samba.example.com Nov 26 11:13:26 mail postfix/smtpd[19662]: dict_ldap_connect: Actual Protocol version used is 3. Nov 26 11:13:26 mail postfix/smtpd[19662]: dict_ldap_connect: Binding to server ldap://samba.example.com with dn cn=Users,dc=company,dc=example,dc=com Nov 26 11:13:26 mail postfix/smtpd[19662]: warning: dict_ldap_connect: Unable to bind to server ldap://samba.example.com with dn cn=Users,dc=company,dc=example,dc=com: 49 (Invalid credentials) Nov 26 11:13:26 mail postfix/smtpd[19662]: warning: ldap:/etc/postfix/ldap-aliases.cf lookup error for "tola.akintola@example.com" Nov 26 11:13:26 mail postfix/smtpd[19662]: maps_find: virtual_alias_maps: [email protected]: search aborted Nov 26 11:13:26 mail postfix/smtpd[19662]: mail_addr_find: tola.akintola@example.com -> (try again) Nov 26 11:13:26 mail postfix/smtpd[19662]: NOQUEUE: reject: RCPT from col0-omc3-s2.col0.hotmail.com[65.55.34.140]: 451 4.3.0 <[email protected]>: Temporary lookup failure; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<col0-omc3-s2.col0.hotmail.com> Nov 26 11:13:26 mail postfix/smtpd[19662]: > col0-omc3-s2.col0.hotmail.com[65.55.34.140]: 451 4.3.0 <[email protected]>: Temporary lookup failure here's another log with successful search result but fialed to get the values of the result Nov 26 12:04:56 mail postfix/smtpd[20463]: dict_ldap_lookup: Using existing connection for LDAP source /etc/postfix/ldap-aliases.cf Nov 26 12:04:56 mail postfix/smtpd[20463]: dict_ldap_lookup: /etc/postfix/ldap-aliases.cf: Searching with filter mail=tola.akintola@example.com Nov 26 12:04:56 mail postfix/smtpd[20463]: dict_ldap_get_values[1]: Search found 1 match(es) Nov 26 12:04:56 mail postfix/smtpd[20463]: dict_ldap_get_values[1]: Leaving dict_ldap_get_values Nov 26 12:04:56 mail postfix/smtpd[20463]: dict_ldap_lookup: Search returned nothing Nov 26 12:04:56 mail postfix/smtpd[20463]: maps_find: virtual_alias_maps: [email protected]: not found Nov 26 12:04:56 mail postfix/smtpd[20463]: dict_ldap_lookup: In dict_ldap_lookup Nov 26 12:04:56 mail postfix/smtpd[20463]: dict_ldap_lookup: /etc/postfix/ldap-aliases.cf: Skipping lookup of key 'tola.akintola': domain mismatch Nov 26 12:04:56 mail postfix/smtpd[20463]: maps_find: virtual_alias_maps: tola.akintola: not found Nov 26 12:04:56 mail postfix/smtpd[20463]: dict_ldap_lookup: In dict_ldap_lookup Nov 26 12:04:56 mail postfix/smtpd[20463]: dict_ldap_lookup: /etc/postfix/ldap-aliases.cf: Skipping lookup of key '@example.com': domain mismatch Nov 26 12:04:56 mail postfix/smtpd[20463]: maps_find: virtual_alias_maps: @example.com: not found Nov 26 12:04:56 mail postfix/smtpd[20463]: mail_addr_find: tola.akintola@example.com -> (not found) My refined ldap-aliases.cf looks like this: server_host = ldap://samba.example.com server_port = 3268 search_base = dc=company, dc=example, dc=com query_filter = mail=%s result_attribute = uid bind_dn = cn=Administrator,cn=Users,dc=company,dc=example,dc=com bind_pw = pass domain = example.com So I'll like to know what ldap filter is appropriate to get this to work. Thanks for helping out.

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  • Configure Postfix to send/relay emails Gmail (smtp.gmail.com) via port 587

    - by tom smith
    Hi. Using Centos 5.4, with Postfix. I can do a mail foo@gmail.com subject: blah test . Cc: and the msg gets sent to gmail, but it resides in the spam folder, which is to be expected. My goal is to be able to generate email msgs, and to have them appear in the regular Inbox! As I understand Postfix/Gmail, it's possible to configure Postfix to send/relay mail via the authenticated/valid user using port 587, which would no longer have the mail be seen as spam. I've tried a number of parameters based on different sites/articles from the 'net, with no luck. Some of the articles, actually seem to conflict with other articles! I've also looked over the stacflow postings on this, but i'm still missing something... Also talked to a few people on IRC (Centos/Postfix) and still have questions.. So, i'm turning to Serverfault, once again! If there's someone who's managed to accomplish this, would you mind posting your main.cf, sasl-passwd, and any other conf files that you use to get this working! If I can review your config files, I can hopefully see where I've screwed up, and figure out how to correct the issue. Thanks for reading this, and any help/pointers you provide! ps, If there is a stackflow posting that speaks to this that I may have missed, feel free to point it out to me! -tom

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  • How do I add 'www' before a subdomain, like www.subdomain.domain.com?

    - by Snehal Masne
    I want to add 'www' in front of a subdomain e.g. www.subdomain.domain.com My blogs are hosted on Blogger and am using GoDaddy for having custom domains. I have HOST @ entries for 'domain' pointing specified by blogger. The following subsdomains are configured by adding CNAME alias as follows : subdomain -> ghs.google.com www -> ghs.google.com For domain (including www.domain) I have one blog. For subdomain, I am pointing it to seperate blog using above entries and 'subdomain.domain.com' works fine. I read articles on this issue and tried adding following CNAME entry but no luck : www.subdomain -> subdomain.domain.com How do I make 'www.subdomain.domain.com' work ?

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  • What Functional features are worth a little OOP confusion for the benefits they bring?

    - by bonomo
    After learning functional programming in Haskell and F#, the OOP paradigm seems ass-backwards with classes, interfaces, objects. Which aspects of FP can I bring to work that my co-workers can understand? Are any FP styles worth talking to my boss about retraining my team so that we can use them? Possible aspects of FP: Immutability Partial Application and Currying First Class Functions (function pointers / Functional Objects / Strategy Pattern) Lazy Evaluation (and Monads) Pure Functions (no side effects) Expressions (vs. Statements - each line of code produces a value instead of, or in addition to causing side effects) Recursion Pattern Matching Is it a free-for-all where we can do whatever the programming language supports to the limit that language supports it? Or is there a better guideline?

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  • How to structure classes in the filesystem?

    - by da_b0uncer
    I have a few (view) classes. Table, Tree, PagingColumn, SelectionColumn, SparkLineColumn, TimeColumn. currently they're flat under app/view like this: app/view/Table app/view/Tree app/view/PagingColumn ... I thought about restructuring it, because the Trees and Tables use the columns, but there are some columns, which only work in a tree, some who work in trees and tables and in the future there are probably some who only work in tables, I don't know. My first idea was like this: app/view/Table app/view/Tree app/view/column/PagingColumn app/view/column/SelectionColumn app/view/column/SparkLineColumn app/view/column/TimeColumn But since the SelectionColumn is explicitly for trees, I have the fear that future developers could get the idea of missuse them. But how to restructure it probably? Like this: app/view/table/panel/Table app/view/tree/panel/Tree app/view/tree/column/PagingColumn app/view/tree/column/SelectionColumn app/view/column/SparkLineColumn app/view/column/TimeColumn Or like this: app/view/Table app/view/Tree app/view/column/SparkLineColumn app/view/column/TimeColumn app/view/column/tree/PagingColumn app/view/column/tree/SelectionColumn

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  • Refactoring in domain driven design

    - by Andrew Whitaker
    I've just started working on a project and we're using domain-driven design (as defined by Eric Evans in Domain-Driven Design: Tackling Complexity in the Heart of Software. I believe that our project is certainly a candidate for this design pattern as Evans describes it in his book. I'm struggling with the idea of constantly refactoring. I know refactoring is a necessity in any project and will happen inevitably as the software changes. However, in my experience, refactoring occurs when the needs of the development team change, not as understanding of the domain changes ("refactoring to greater insight" as Evans calls it). I'm most concerned with breakthroughs in understanding of the domain model. I understand making small changes, but what if a large change in the model is necessary? What's an effective way of convincing yourself (and others) you should refactor after you obtain a clearer domain model? After all, refactoring to improve code organization or performance could be completely separate from how expressive in terms of the ubiquitous language code is. Sometimes it just seems like there's not enough time to refactor. Luckily, SCRUM lends it self to refactoring. The iterative nature of SCRUM makes it easy to build a small piece and change and it. But over time that piece will get larger and what if you have a breakthrough after that piece is so large that it will be too difficult to change? Has anyone worked on a project employing domain-driven design? If so, it would be great to get some insight on this one. I'd especially like to hear some success stories, since DDD seems very difficult to get right. Thanks!

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  • Secure an Application/Software by expiration with Date?

    - by JNL
    I have been working on some software application and I update them every 6 months. Currently, the way I track the date is by extracting the date from the system when the user installes the application, encrypt it and store it in a file locally. Whenever the application is started, it checks if 6 months have passed, then it works or it doesn't, in which case it shows an error message telling the user to update. I wonder whether there is a better way to do this. Any comments or suggestions would be highly appreciated

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  • Explanation needed, for “Ask, don't tell” approach?

    - by the_naive
    I'm taking a course on design patterns in software engineering and here I'm trying to understand the good and the bad way of design relating to "coupling" and "cohesion". I could not understand the concept described in the following image. The example of code shown in the image is ambiguous to me, so I can't quite clearly get what exactly "Ask, don't tell!" approach mean. Could you please explain?

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  • When should method overloads be refactored?

    - by Ben Heley
    When should code that looks like: DoThing(string foo, string bar); DoThing(string foo, string bar, int baz, bool qux); ... DoThing(string foo, string bar, int baz, bool qux, string more, string andMore); Be refactored into something that can be called like so: var doThing = new DoThing(foo, bar); doThing.more = value; doThing.andMore = otherValue; doThing.Go(); Or should it be refactored into something else entirely? In the particular case that inspired this question, it's a public interface for an XSLT templating DLL where we've had to add various flags (of various types) that can't be embedded into the string XML input.

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  • NoSQL is not about object databases

    NoSQL as a movement is an interesting beast. I kinda like that its negatively defined (I happen to belong myself to at least one other such a-community). Its not in its roots about proposing one specific new silver bullet to kill an old problem. its about challenging the consensus. Actually, blindly and systematically replacing relational databases with object databases would just replace one set of issues with another. No, the point is to recognize that relational databases are not a universal...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Collision filtering by object, team

    - by Bill Zimmerman
    Hi, I am looking for a good method to determine which objects will be considered for collision with other objects. My current idea is that each object has the following properties: alwaysCollidesWith = [list of objects that will always trigger a collision check] neverCollidesWith = [lost of objects that will never be considered] teamCollidesWith = [list of objects that will be checked, provided they belong to a different team] For example: -projectiles never have to be checked for collisions with other projectiles -players are always checked for collisions with players, regardless of team -projectiles are only considered for collisions if they collide with another teams players Does anyone see any weaknesses with this approach? Can anyone recommend a better approach?

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  • Triggering custom events in AJAX callbacks

    - by Sabrina Gelbart
    I'm pretty new to JavaScript, but one of the things that's been frustrating is that our AJAX callbacks have been getting packed with different functionality, making it difficult to keep everything separated and organized. I'm really new to programming, I have a feeling learning MVC a bit more would help me, but for now using custom events seems like it could help me keep my code a lot cleaner and prevent some problems. Here's what I'm talking about: function myAjaxFunction(){ $.post('ajax/test.html', function(data) { $(document).trigger('testDataLoaded',data); }); } function myOtherFunctionThatsDependentUponAjax(){ $(document).one('testDataLoaded', function(data){ alert (data); } } I also don't know if it's ok that I'm triggering document or not... Are there any patterns that look like this that I can read more about? What are the potential problems with this?

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  • WGet or cURL: Mirror Site from http://site.com And No Internal Access

    - by alharaka
    I have tried wget -m wget -r and a whole bunch of variations. I am getting some of the images on http://site.com, one of the scripts, and none of the CSS, even with the fscking -p parameter. The only HTML page is index.html and there are several more referenced, so I am at a loss. curlmirror.pl on the cURL developers website does not seem to get the job done either. Is there something I am missing? I have tried different levels of recursion with only this URL, but I get the feeling I am missing something. Long story short, some school allows its students to submit web projects, but they want to know how they can collect everything for the instructor who will grade it, instead of him going to all the externally hsoted sites. UPDATE: I think I figured out the issue. I though the links to the other pages were in the index.html page that downloaded. I was way off. Turns out the footer of the page, which has all the navigation links, is handled by a JavaScript file Include.js, which reads JLSSiteMap.js and some other JS files to do page navigation and the like. As a result, wget does not pick up an other dependencies because a lot of this crap is handled not on web pages. How can I handle such a website? This is one of several problem cases. I assume little can be done if wget cannot parse JavaScript.

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  • How to avoid general names for abstract classes?

    - by djechlin
    In general it's good to avoid words like "handle" or "process" as part of routine names and class names, unless you are dealing with (e.g.) file handles or (e.g.) unix processes. However abstract classes often don't really know what they're going to do with something besides, say, process it. In my current situation I have an "EmailProcessor" that logs into a user's inbox and processes messages from it. It's not really clear to me how to give this a more precise name, although I've noticed the following style matter arises: better to treat derived classes as clients and named the base class by the part of the functionality it implements? Gives it more meaning but will violate is-a. E.g. EmailAcquirer would be a reasonable name since it's acquiring for the derived class, but the derived class won't be acquiring for anyone. Or just really vague name since who knows what the derived classes will do. However "Processor" is still too general since it's doing many relevant operations, like logging in and using IMAP. Any way out of this dilemma? Problem is more evident for abstract methods, in which you can't really answer the question "what does this do?" because the answer is simply "whatever the client wants."

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  • Differentiate procedural language(c) from oop languages(c++)

    - by niko
    I have been trying to differentiate c and c++(or oop languages) but I don't understand where the difference is. Note I have never used c++ but I asked my friends and some of them to differentiate c and c++ They say c++ has oop concepts and also the public, private modes for definition of variables and which c does not have though. Seriously I have done vb.net programming for a while 2 to 3 months, I never faced a situation to use class concepts and modes of definition like public and private. So I thought what could be the use for these? My friend explained me a program saying that if a variable is public, it can be accessed anywhere I said why not declare it as a global variable like in c? He did not get back to my question and he said if a variable is private it cannot be accessed by some other functions I said why not define it as a local variable, even these he was unable to answer. No matter where I read private variables cannot be accessed whereas public variables can be then why not make public as global and private as local whats the difference? whats the real use of public and private ? please don't say it can be used by everyone, I suppose why not we use some conditions and make the calls? I have heard people saying security reasons, a friend said if a function need to be accessed it should be inherited first. He explained saying that only admin should be able to have some rights and not all so that functions are made private and inherited only by the admin to use Then I said why not we use if condition if ( login == "admin") invoke the function he still did not answer these question. Please clear me with these things, I have done vb.net and vba and little c++ without using oop concepts because I never found their real use while I was writing the code, I'm a little afraid am I too back in oop concepts?

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  • Blender Object Appearing Gray when all Lights are Off

    - by celestialorb
    I have an issue with Blender where, when I turn my only light off (a sun lamp) and render the image my object appears gray rather than black (and thus, not appear to the camera). I can't figure out why this is happening. Here's what I just did in my scene: Added a new UV Sphere mesh (to make a total of two spheres), made it visible to the camera, turned off the sun lamp (by setting energy to 0), and rendered. The result I obtained is below. I discovered this when attempting to render the first sphere with a material/texture on it and it was too bright. The material on the spheres (which are different) are very basic, there's no emit, diffuse and specular are at default values. Could there be an issue with the way my camera is setup? Thanks in advance!

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  • Is there any functional difference between immutable value types and immutable reference types?

    - by Kendall Frey
    Value types are types which do not have an identity. When one variable is modified, other instances are not. Using Javascript syntax as an example, here is how a value type works. var foo = { a: 42 }; var bar = foo; bar.a = 0; // foo.a is still 42 Reference types are types which do have an identity. When one variable is modified, other instances are as well. Here is how a reference type works. var foo = { a: 42 }; var bar = foo; bar.a = 0; // foo.a is now 0 Note how the example uses mutatable objects to show the difference. If the objects were immutable, you couldn't do that, so that kind of testing for value/reference types doesn't work. Is there any functional difference between immutable value types and immutable reference types? Is there any algorithm that can tell the difference between a reference type and a value type if they are immutable? Reflection is cheating. I'm wondering this mostly out of curiosity.

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  • Central Exception Handler

    - by J-unior
    Recently I've been thinking about a general ExceptionHandler, that I could initialize once in my app context and inject it everywhere. The idea that it will have quite simple interface with just public void handle(Exception ex), and then according to exception type it should decide what to do, maybe just log it, or show an alert message to the user, or maybe kill the whole app. The question is, what is the prettiest way to write such handler without lots of instanceofs? Unfortunately googling gives me only the default exception handler for RuntimeException that was introduced in Java 5. My first idea is to create an enum, that will have Class field for exception type and it will return the appropriate execution point, for example a concrete exception handler that also implements the interface public void handle(Exception ex), but with the required casting already.

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  • Project structure: where to put business logic

    - by Mister Smith
    First of all, I'm not asking where does business logic belong. This has been asked before and most answers I've read agree in that it belongs in the model: Where to put business logic in MVC design? How much business logic should be allowed to exist in the controller layer? How accurate is "Business logic should be in a service, not in a model"? Why put the business logic in the model? What happens when I have multiple types of storage? However people disagree in the way this logic should be distributed across classes. There seem to exist three major currents of thought: Fat model with business logic inside entity classes. Anemic model and business logic in "Service" classes. It depends. I find all of them problematic. The first option is what most Fowlerites stick to. The problem with a fat model is that sometimes a business logic funtion is not only related to a class, and instead uses a bunch of other classes. If, for example, we are developing a web store, there should be a function that calcs an order's total. We could think of putting this function inside the Order class, but what actually happens is that the logic needs to use different classes, not only data contained in the Order class, but also in the User class, the Session class, and maybe the Tax class, Country class, or Giftcard, Payment, etc. Some of these classes could be composed inside the Order class, but some others not. Sorry if the example is not very good, but I hope you understand what I mean. Putting such a function inside the Order class would break the single responsibility principle, adding unnecesary dependences. The business logic would be scattered across entity classes, making it hard to find. The second option is the one I usually follow, but after many projects I'm still in doubt about how to name the class or classes holding the business logic. In my company we usually develop apps with offline capabilities. The user is able to perform entire transactions offline, so all validation and business rules should be implemented in the client, and then there's usually a background thread that syncs with the server. So we usually have the following classes/packages in every project: Data model (DTOs) Data Access Layer (Persistence) Web Services layer (Usually one class per WS, and one method per WS method). Now for the business logic, what is the standard approach? A single class holding all the logic? Multiple classes? (if so, what criteria is used to distribute the logic across them?). And how should we name them? FooManager? FooService? (I know the last one is common, but in our case it is bad naming because the WS layer usually has classes named FooWebService). The third option is probably the right one, but it is also devoid of any useful info. To sum up: I don't like the first approach, but I accept that I might have been unable to fully understand the Zen of it. So if you advocate for fat models as the only and universal solution you are welcome to post links explaining how to do it the right way. I'd like to know what is the standard design and naming conventions for the second approach in OO languages. Class names and package structure, in particular. It would also be helpful too if you could include links to Open Source projects showing how it is done. Thanks in advance.

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  • Which points should be covered in basic Bachelors' level C++ course?

    - by Gulshan
    I have a young lecturer friend who is going to take the C++ course for the bachelors' degree in CS. He asked me for some suggestions regarding how the course should be organized. Now I am asking you. I have seen many trends in universities which leads to a nasty experience of C++. So, please suggest from a professional programmer's point of view. For your information, the students going to take the course, have taken course like "Introduction to programming with C" in previous semester.

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  • Design patterns and multiple programming language

    - by Eduard Florinescu
    I am referring here to the design patterns found in the GOF book. First how I see it, there are a few peculiarities to design pattern and knowing multiple language knowledge, for example in Java you really need a singleton but in Python you can do without it you write a module, I saw somewhere a wiki trying to write all GOF patterns for JavaScript and the entries where empty, I guess because it might be a daunting task. If there is someone who is using design patterns and is programming in multiple programming languages supporting the OOP paradigm and can give me a hint on how should I approach design patterns that might help me in all languages I use(Java, JavaScript, Python, Ruby): Can I write good application without knowing exactly the GOF design patterns or I might need some of them which might be crucial and if yes which one, are they alternatives to GOF for specific languages, and should a programmer or a team make its own design patterns set?

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  • A design pattern for data binding an object (with subclasses) to asp.net user control

    - by Rohith Nair
    I have an abstract class called Address and I am deriving three classes ; HomeAddress, Work Address, NextOfKin address. My idea is to bind this to a usercontrol and based on the type of Address it should bind properly to the ASP.NET user control. My idea is the user control doesn't know which address it is going to present and based on the type it will parse accordingly. How can I design such a setup, based on the fact that, the user control can take any type of address and bind accordingly. I know of one method like :- Declare class objects for all the three types (Home,Work,NextOfKin). Declare an enum to hold these types and based on the type of this enum passed to user control, instantiate the appropriate object based on setter injection. As a part of my generic design, I just created a class structure like this :- I know I am missing a lot of pieces in design. Can anybody give me an idea of how to approach this in proper way.

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