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• Analysis and Design for Functional Programming

  - by edalorzo

  How do you deal with analysis and design phases when you plan to develop a system using a functional programming language like Haskell? My background is in imperative/object-oriented programming languages, and therefore, I am used to use case analysis and the use of UML to document the design of program. But the thing is that UML is inherently related to the object-oriented way of doing software. And I am intrigued about what would be the best way to develop documentation and define software designs for a system that is going to be developed using functional programming. Would you still use use case analysis or perhaps structured analysis and design instead? How do software architects define the high-level design of the system so that developers follow it? What do you show to you clients or to new developers when you are supposed to present a design of the solution? How do you document a picture of the whole thing without having first to write it all? Is there anything comparable to UML in the functional world?

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• What is a dotted pair's analogy in other Lisp implementations?

  - by octopusgrabbus

  What is Scheme's dotted pair construct analogous to in other Lisp implementations? I can make a vector or list quite easily, and understand those in Clojure, even though the syntax is a little different, like Clojure's vectors use square brackets []. However, seeing a dotted pair for the first time threw me. It almost looks like it is an implementation of of map. I'm not looking for a discussion, but more for use or the dotted pair equivalent in other Lisp dialects, like Clojure, or even Python. Thanks.

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• how to translate Haskell into Scalaz?

  - by TOB

  One of my high school students and I are going to try to do a port of Haskell's Parsec parser combinator library into Scala. (It has the advantage over Scala's built-in parsing library that you can pass state around fairly easily because all the parsers are monads.) The first hitch I've come across is trying to figure out how Functor works in scalaz. Can someone explain how to convert this Haskell code: data Reply s u a = Ok a !(State s u) ParseError | Error ParseError instance Functor (Reply s u) where fmap f (Ok x s e) = Ok (f x) s e fmap _ (Error e) = Error e -- XXX into Scala (using Scalaz, I assume). I got as far as sealed abstract class Reply[S, U, A] case class Ok[S, U, A](a: A, state: State[S, U], error: ParseError) extends Reply[S, U, A] case class Error[S, U, A](error: ParseError) extends Reply[S, U, A] and know that I should make Reply extend the scalaz.Functor trait, but I can't figure out how to do that. (Mostly I'm having trouble figuring out what the F[_] parameter does.) Any help appreciated! Thanks, Todd

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• Who calls the Destructor of the class when operator delete is used in multiple inheritance.

  - by dicaprio-leonard

  This question may sound too silly, however , I don't find concrete answer any where else. With little knowledge on how late binding works and virtual keyword used in inheritance. As in the code sample, when in case of inheritance where a base class pointer pointing to a derived class object created on heap and delete operator is used to deallocate the memory , the destructor of the of the derived and base will be called in order only when the base destructor is declared virtual function. Now my question is : 1) When the destructor of base is not virtual, why the problem of not calling derived dtor occur only when in case of using "delete" operator , why not in the case given below: derived drvd; base *bPtr; bPtr = &drvd; //DTOR called in proper order when goes out of scope. 2) When "delete" operator is used, who is reponsible to call the destructor of the class? The operator delete will have an implementation to call the DTOR ? or complier writes some extra stuff ? If the operator has the implementation then how does it looks like , [I need sample code how this would have been implemented]. 3) If virtual keyword is used in this example, how does operator delete now know which DTOR to call? Fundamentaly i want to know who calls the dtor of the class when delete is used. Sample Code class base { public: base() { cout<<"Base CTOR called"<<endl; } virtual ~base() { cout<<"Base DTOR called"<<endl; } }; class derived:public base { public: derived() { cout<<"Derived CTOR called"<<endl; } ~derived() { cout<<"Derived DTOR called"<<endl; } }; I'm not sure if this is a duplicate, I couldn't find in search. int main() { base *bPtr = new derived(); delete bPtr;// only when you explicitly try to delete an object return 0; }

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• UITableViewCell outlets not set during bundle load (possibly very elementary question)

  - by Jan Zich

  What are the most common reasons for an outlet (a class property) not being set during a bundle load? I'm sorry; most likely I'm not using the correct terms. It's my first steps with iPhone OS development and Objective-C, so please bear with me. Here is more details. Basically, I'm trying to create a table view based form with a fixed number of static rows. I followed this example: http://developer.apple.com/iphone/library/documentation/userexperience/conceptual/TableView_iPhone/TableViewCells/TableViewCells.html Scroll down to The Technique for Static Row Content please. I have one nib file with one table view, three table cells and all connections set as in the example. The problem is that the corresponding cell properties in my controller are never initialised. I get an exception in cellForRowAtIndexPath complaining that the returned cell is nil: UITableView dataSource must return a cell from tableView:cellForRowAtIndexPath. Here are the relevant parts from the implementation of the controller: @synthesize cellA; @synthesize cellB; @synthesize cellC; - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return 3; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { switch (indexPath.row) { case 0: return cellA; break; case 1: return cellB; break; case 2: return cellC; break; default: return nil; } } And here is the interface part: @interface AssociatePhoneViewController : UITableViewController { UITableViewCell *cellA; UITableViewCell *cellB; UITableViewCell *cellB; } @property (nonatomic, retain) IBOutlet UITableViewCell *cellA; @property (nonatomic, retain) IBOutlet UITableViewCell *cellB; @property (nonatomic, retain) IBOutlet UITableViewCell *cellC; @end This must be possibly one of the the most embarrassing questions on StackOverflow. It looks like the most basic example code. Is is possible that the cells are not instantiated with the nib file? I have them on the same level before the tabula view in the nib file. I tried to move them after the table view, but it did not make any difference. Are table cells in some way special? Do I need to set some flag or some property on them in the nib file? I was under the impression that all classes (views, windows, controllers …) listed in a nib file are simply instantiated (and linked using the provided connections). Could it possibly be some memory issue? The cell properties in my controller are not defined in any special way.

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• VirtualBox and Ubuntu Mount Error

  - by skaz

  I have Ubuntu 10 as the guest OS on a Windows 7 machine. I have been trying to setup shares through VirtualBox, but nothing is working. First, I create the share in VirtualBox and point it to a Windows folder. Then I try to mount the drive in Linux, but I keep getting /sbin/mount.vboxsf: mounting failed with the error: Protocol error I have read so many solutions to this, but none seem to work. I have tried: Using the mount.vboxsf syntax Reinstalling VBox additions Rebooting Enabling and trying as root account Any other ideas? In case I am doing something dumb, here are more details: I made a share called "Test" in VBox Shared folders. Then I made a directory in ubuntu named "test2". Then I tried to execute this command: sudo mount -t vboxsf Test /mnt/test2 Thank you!

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• indicator-chars doesn't work on Oneiric

  - by Lucio

  I downloaded Indicator-Char and unzipped the files. I added the characters there I wanted perfectly. When I run the python script it loads the daemon and I can see this characters. But the problem is that when I click on them, not copied anything to the clipboard. I see the code where is the copy function, is the following. def on_char_click(self, widget, char): cb = gtk.Clipboard(selection="PRIMARY") cb.set_text(char) Is a syntax problem? There is a problem on my system?

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• What is use of universal character names in identifiers in C++11

  - by Jan Hudec

  The new C++ standard specifies universal character names, written as \uNNNN and \UNNNNNNNN and representing the characters with unicode codepoints NNNN/NNNNNNNN. This is useful with string literals, especially since explicitly UTF-8, UTF-16 and UCS-4 string literals are also defined. However, the universal character literals are also allowed in identifiers. What is the motivation behind that? The syntax is obviously totally unreadable, the identifiers may be mangled for the linker and it's not like there was any standard function to retrieve symbols by name anyway. So why would anybody actually use an identifier with universal character literals in it?

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• Enzo Backup for SQL Azure Beta Released!

  - by ScottKlein

  Blue Syntax is happy to announce the release of their SQL Azure database backup product! Enzo Backup for SQL Azure offers unparalleled backup and restored functionlity and flexibility of a SQL Azure database. You can download the beta release here: http://www.bluesyntax.net/backup.aspx With Enzo Backup for SQL Azure, you can: Create a backup blob, or a backup file from a SQL Azure database Restore a SQL Azure database from a backup blob, or a backup file Perform limited backup and restore of SQL Server databases (see details) Run backups entirely in the cloud using a remote agent Backup a single schema of a database Restore specific tables only Copy backup devices from on-premise to the cloud Use a command-line utility to perform backup operations Perform transactionally consistent backups for SQL Azure Please download it and provide us your feed back!

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• jQuery sortColumns plugin: How to sort correctly with rowspan

  - by Thang Pham

  Following this post jQuery table sort (github link: https://github.com/padolsey/jQuery-Plugins/blob/master/sortElements/jquery.sortElements.js), I am successfully sort columns, however it does not work in the case of rowspan: For example, case like this Grape 3,096,671M 1,642,721M Apple 2,602,750M 3,122,020M When I click on the second column, it try to sort Apple 2,602,750M 1,642,721M Grape 3,096,671M 3,122,020M which as you can see is not correct, please any jQuery guru help me fix this problem. Here is my code var inverse = false; function sortColumn(index){ index = index + 1; var table = jQuery('#resultsTable'); table.find('td').filter(function(){ return jQuery(this).index() == index; }).sortElements(function(a, b){ a = convertToNum($(a).text()); b = convertToNum($(b).text()); return ( isNaN(a) || isNaN(b) ? a > b : +a > +b ) ? inverse ? -1 : 1 : inverse ? 1 : -1; },function(){ return this.parentNode; }); inverse = !inverse; } function convertToNum(str){ if(isNaN(str)){ var holder = ""; for(i=0; i<str.length; i++){ if(!isNaN(str.charAt(i))){ holder += str.charAt(i); } } return holder; }else{ return str; } } Question: 1.How do I sort this with rowspan. THE NUMBER OF ROWSPAN IS NOT ALWAYS THE SAME. The above example both Grape and Apple have rowspan of 2, but this is not always the case. 2.Can any explain this syntax: return ( isNaN(a) || isNaN(b) ? a > b : +a > +b ) ? inverse ? -1 : 1 : inverse ? 1 : -1; So I can see that if either a or b is not a number, then do string comparison otherwise do number comparison, but I dont understand the inverse ? -1 : 1 : inverse ? 1 : -1;

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• Tentative date casting in tsql

  - by Tewr

  I am looking for something like TRYCAST in TSQL or an equivalent method / hack. In my case I am extracting some date data from an xml column. The following query throws "Arithmetic overflow error converting expression to data type datetime." if the piece of data found in the xml cannot be converted to datetime (in this specific case, the date is "0001-01-01" in some cases). Is there a way to detect this exception before it occurs? select [CustomerInfo].value('(//*:InceptionDate/text())[1]', 'datetime') FROM Customers An example of what I am trying to achieve in pseudocode with an imagined tsql function TRYCAST(expr, totype, defaultvalue): select TRYCAST( [CustomerInfo].value('(//*:InceptionDate/text())[1]', 'nvarchar(100)'), datetime, null) FROM Customers

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• Does approaching SICP in clojure have a high chance of success? [on hold]

  - by ironicaldiction

  I am a third year bachelor student in a software engineering program, and I brought up the idea of reading SICP to an adviser to gain a deeper and more fundamental understanding of the principles behind all this software we engineer. He suggested not to learn scheme to complete the book (because it's not as common as modern dialects of lisp) but to do the exercises in clojure instead. My worry is that completing exercises in clojure instead of scheme will make an already difficult book tortuous. If I do attempt the book's exercises in the more modern clojure, will it be difficult to succeed (for example, because I can't find any real solutions, the syntax they teach for scheme is different, etc.), or do you think approaching the book in clojure could be just as successful as approaching it in scheme? I'm really not knowledgeable enough about either clojure or scheme to make an argument about this, so I wanted to know if I should bring it up or not.

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• How do I start Nautilus as root?

  - by Pho swan

  I got problem with nautilus in Ubuntu 12.04 LTS when i run command "gksu nautilus /" password ask box appear and I type my super-user password , than password box is disappear and nautilus is not open. . when i try to open nautilus via normal user in command box . "nautilus" the folder is open up. when i try in terminal ... $sudo nautilus I got following error $ sudo nautilus / ** (nautilus:8523): WARNING **: Command line `dbus-launch --autolaunch=2c8ce9b7da2257c2609b749700000007 --binary-syntax --close-stderr' exited with non-zero exit status 1: Autolaunch error: X11 initialization failed.\n Could not parse arguments: Cannot open display: how can i fix this error..

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• Approaching SICP in Clojure instead of Scheme

  - by ironicaldiction

  I am a third year bachelor student in a software engineering program, and I brought up the idea of reading SICP to an adviser to gain a deeper and more fundamental understanding of the principles behind all this software we engineer. He suggested not to learn Scheme to complete the book (because it's not as common as modern dialects of Lisp) but to do the exercises in Clojure instead. It's an already difficult book, if I do attempt the book's exercises in the more modern Clojure, how would that work? For example, I can't find any real solutions, the syntax they teach for Scheme is different, etc.

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• MySQL dual license behavior

  - by jromero

  Hi SO, I'm running a commercial(closed source) Web App development for the first time. Initially I considered MySQL the most feasible option for a DB, until I get quite confused about its dual license behavior. If I want a commercial application do I still can use the GPL version of MySQL or I must get a license? The same question in a different way: If I use MySQL's GPL version does that force me to license the whole app under GPL? Either case I would go with PostgreSQL, I just want to make really really sure about this. Even in SO I've seen related("duplicates") questions but never a clear answer... All other tools I'm gonna use to code the project are licensed under BSD or MIT. Just in case, the role of MySQL in the project is merely as relational DB to store persistent data and query it. I'd really appreciate if someone can clarify this for me. Regards, thanks in advanced.

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• Smarty: Tags Matching and Unpaired Tags Errors

  - by Martin Fousek

  Hello, today we would like to show you other improvements we have prepared in PHP Smarty Framework. Let's talk about highlighting of matching tags and error reporting of unpaired ones. Tags Matching Some of your enhancements talked  about paired tags matching to be able to see matching tags at first glance.We have good news for you that this feature you can try out already in our latest PHP Development builds and of course later in NetBeans 7.3. Unpaired Tags Errors To make easier detecting of template syntax issues, we provide basic tags pairing. If you forgot to begin some paired Smarty tag or you end it unexpectedly you should get error hint which complains about your issue. That's all for today. As always, please test it and report all the issues or enhancements you find in NetBeans BugZilla (component php, subcomponent Smarty).

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• How can I force input to uppercase in an asp.net textbox?

  - by Aheho

  I'm writing an asp.net application. I have a textbox on a webform and I want to force whatever the user types to upper case. I'd like to do this on the front end. You should also note that there is a validation control on this textbox, so I want to make sure the solution doesn't interfere with the asp.net validation. Clarification: It appears that the CSS text-tranform makes the user input appear in uppercase, however under the hood, it's still lower case as the validation control fails. You see, my validation control checks to see if a valid state code is entered, however the regex expression I"m using only works with uppercase characters.

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• How do I recover from an unchecked exception?

  - by erickson

  Unchecked exceptions are alright if you want to handle every failure the same way, for example by logging it and skipping to the next request, displaying a message to the user and handling the next event, etc. If this is my use case, all I have to do is catch some general exception type at a high level in my system, and handle everything the same way. But I want to recover from specific problems, and I'm not sure the best way to approach it with unchecked exceptions. Here is a concrete example. Suppose I have a web application, built using Struts2 and Hibernate. If an exception bubbles up to my "action", I log it, and display a pretty apology to the user. But one of the functions of my web application is creating new user accounts, that require a unique user name. If a user picks a name that already exists, Hibernate throws an org.hibernate.exception.ConstraintViolationException (an unchecked exception) down in the guts of my system. I'd really like to recover from this particular problem by asking the user to choose another user name, rather than giving them the same "we logged your problem but for now you're hosed" message. Here are a few points to consider: There a lot of people creating accounts simultaneously. I don't want to lock the whole user table between a "SELECT" to see if the name exists and an "INSERT" if it doesn't. In the case of relational databases, there might be some tricks to work around this, but what I'm really interested in is the general case where pre-checking for an exception won't work because of a fundamental race condition. Same thing could apply to looking for a file on the file system, etc. Given my CTO's propensity for drive-by management induced by reading technology columns in "Inc.", I need a layer of indirection around the persistence mechanism so that I can throw out Hibernate and use Kodo, or whatever, without changing anything except the lowest layer of persistence code. As a matter of fact, there are several such layers of abstraction in my system. How can I prevent them from leaking in spite of unchecked exceptions? One of the declaimed weaknesses of checked exceptions is having to "handle" them in every call on the stack—either by declaring that a calling method throws them, or by catching them and handling them. Handling them often means wrapping them in another checked exception of a type appropriate to the level of abstraction. So, for example, in checked-exception land, a file-system–based implementation of my UserRegistry might catch IOException, while a database implementation would catch SQLException, but both would throw a UserNotFoundException that hides the underlying implementation. How do I take advantage of unchecked exceptions, sparing myself of the burden of this wrapping at each layer, without leaking implementation details?

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• Detecting/Repairing NSConnection failure

  - by anthony

  I would like to use NSConnection/NSDistributedObject for interprocess communication. I would like the client to be able to handle the case where the server is only occasionally reachable. How can I determine if sending a message to the NSConnection will fail or has failed? Currently if my server (the process that has vended the remote object) dies, the client will crash if it sends a selector to the remote object. Ideally I'd like to have a wrapper for the remote object that can lazily instantiate (or reinstantiate) the connection, and return a default value in the case where the connection could not be instantiated, or the connection has failed. I don't really know the correct way to do this using objective c. Here's some pseudocode representing this logic: if myConnection is null: instantiate myConnection if MyConnection is null: return defaultValue try return [myConnection someMethod] catch myConnection = null return defaultValue

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• C# define string format of double/floats to be US english by default

  - by neil

  Hi, I have got several thousands of lines of a web application source code, initially written on a US development system, to maintain. It makes heavy use of SQL statement strings, which are combined on the fly, e.g. string SQL = "select * from table where double_value = " + Math.Round(double_value, 2); Don't comment on bad programming style, that doesn't help me in this case :) The cruix: My system uses a German locale, which in turn leads to wrong SQL statements, like this: "select * from table where double_value = 15,5" (Note the comma as decimal separator instead of a point). Question: What is the most "elegant" way to change the locale of the web app in this case) to US or UK in order to prevent being forced to change and inspect every single line of code? .net 3.5 is not an option (would give me the chance to overwrite ToString() in an extension class) Kind regards

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• DialogBox in Win32 - Prevent multiple instance

  - by UK

  Hello all, I have a program which creates DialogBox window when user clicks the menu item from tray icon, case ID_OPTIONS: DialogBox ( GetModuleHandle ( NULL ), MAKEINTRESOURCE ( IDD_SETUP_DIALOG ), hWnd, reinterpret_cast<DLGPROC>(SetupDlgProc) ); return 0; But the problem here is everytime when users clicks item from tray , a new instance of the dialogbox appears. Is there anyway to prevent this multiple instance ? BTW, my SetupDlgProc looks like this, BOOL CALLBACK SetupDlgProc ( HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam ) { switch ( Message ) { case WM_INITDIALOG: ... } } Thanks for your help.

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• How do I return the entire set / array using NSPredicate?

  - by Prairiedogg

  I'm building a carArray and want to filter the contents conditionally, using an NSPredicate, like so: NSPredicate *pred; switch (carType) { case FreeCar: pred = [NSPredicate predicateWithFormat:@"premium = NO"]; break; case PremiumCar: pred = [NSPredicate predicateWithFormat:@"premium = YES"]; break; default: pred = [NSPredicate predicateWithFormat:@"SOME PREDICATE THAT RETURNS EVERYTHING"]; break; } self.carArray = [aCarArrayIGotFromSomewhere filteredArrayUsingPredicate:pred]; My question is, what is the correct syntax for the value I've stubbed in as SOME PREDICATE THAT RETURNS EVERYTHING which returns all of the instances in the array / set? PS - I know the answer and will post it immediately, just sharing it for everyone's reference as an earlier search on SO did not yield the result.

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• How do I combine all lines in a text file into a single line?

  - by John

  I want to get all lines in a text into one line. I'm a beginner at coding trying to learn by doing. I've spent four hours trying to solve this problem. I know there's a simple solution to this problem. Here's what I've been trying. sed -e 'N;s/\n//' myfile.txt #Does nothing sed -e :a -e N -e 's/\n/ /' -e ta myfile.txt #output all messed up and I can't make head nor tail of the syntax cat myfile.txt | tr -d '\n' myfile.txt # Deletes all lines Here's the text file: 500212 262578-4-4 23200 GRIFFITH LABORATORIES LTD GRIFFITH LABORATORIES SOUTH DUBLIN COUNTY COUNCIL OFFICE OFFICE (INDUSTRIAL) List Rateable 2 Pineview Industrial Estate Firhouse Road Knocklyon 31 Dec 2007 01 Jan 2008" I can't figure out where I've gone wrong....

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• Java dev learning Python: what concepts do I need to wrap my head around?

  - by LRE

  I've run through a few tutorials and written some small projects. I'm right in the middle of a small project now infact. All is going well enough thanks in no small part to Uncle Google (who usually points me to Stackoverflow ;-) Several times in the last few days I've found myself wondering "what am I missing?" - I feel that I'm still thinking in Java as I write in Python. This question over at StackOverflow is full of tips about what resources to read up on for learning Python, but I still feel that I'm a Java dev with a dictionary (pun unintended) to translate into Python. What I really want to do is refactor my head to be able to write Pythonic Python instead of Java disguised as Python (not that I want to loose my Java skills). So, the crux of my question is: what concepts does a Java dev really need to learn to think Pythonic? This includes anything that needs to be un-learnt. ps: I consider language syntax to not be particularly relevant to this question.

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• Can't find a Wordpress image/photo gallery plugin

  - by mgroves

  I've been looking at Wordpress plugins for photo galleries (so maybe this is for superuser.com), and I've been very frustrated so far. It seems like what I'd like to do would be a very common use case: Admin: Be able to upload multiple pictures (at a time) Admin: Be able to assign a "gallery" to those pictures as I upload them User: Be able to go to a page with a (paged) list of all galleries User: Be able to click on gallery and view the images (again, probably paged) in that gallery User: Be able to click on an image to get larger/largest sizes User: Be able to leave comments on individual pictures (this is a "nice to have") The images/galleries could be totally independent of posts/pages, but it would be nice to be able to embed those images/galleries into posts/pages when necessary. Is there anything out there like this that I'm missing? I've tried a handful of plugins and none of them seem to be for a use case anywhere close to what I'm looking for. One of the reasons I'm trying to use Wordpress is to reduce time spent coding everything I want.

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