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• Task vs. process, is there really any difference?

  - by DASKAjA

  Hi there, I'm studying for my final exams in my CS major on the subject distributed systems and operating systems. I'm in the need for a good definition for the terms task, process and threads. So far I'm confident that a process is the representation of running (or suspended, but initiated) program with its own memory, program counter, registers, stack, etc (process control block). Processes can run threads which share memory, so that communication via shared memory is possible in contrast to processes which have to communicate via IPC. But what's the difference between tasks and process. I often read that they're interchangable and that the term task isn't used anymore. Is that really true?

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• Why are difference lists more efficient than regular concatenation?

  - by Craig Innes

  I am currently working my way through the Learn you a haskell book online, and have come to a chapter where the author is explaining that some list concatenations can be ineffiecient: For example ((((a ++ b) ++ c) ++ d) ++ e) ++ f Is supposedly inefficient. The solution the author comes up with is to use 'difference lists' defined as newtype DiffList a = DiffList {getDiffList :: [a] -> [a] } instance Monoid (DiffList a) where mempty = DiffList (\xs -> [] ++ xs) (DiffList f) `mappend` (DiffList g) = DiffList (\xs -> f (g xs)) I am struggling to understand why DiffList is more computationally efficient than a simple concatenation in some cases. Could someone explain to me in simple terms why the above example is so inefficient, and in what way the DiffList solves this problem?

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• sqlalchemy: what is the difference between declaring the cascade within the foreign key vs relation?

  - by steve

  what is the difference between declaring the cascade within a foreign key vs relations? class Contact(Base): __tablename__ = 'contacts' id = Column(Integer, primary_key=True) addresses = relation("Address", backref="contact") class Address(Base): __tablename__ = 'addresses' id = Column(Integer, primary_key=True) contact_id = Column(Integer, ForeignKey('contact.id', onupdate="CASCADE", ondelete="CASCADE"))) vs class Contact(Base): __tablename__ = 'contacts' id = Column(Integer, primary_key=True) addresses = relation("Address", backref="contact", cascade="all, delete-orphan") class Address(Base): __tablename__ = 'addresses' id = Column(Integer, primary_key=True) contact_id = Column(Integer, ForeignKey('contact.id')) with the foreign key declaration, it seems like the cascade is enforced at the database level. how does the relations approach work? thanks!

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• Interview question: difference between object and object-oriented languages.

  - by Bar

  My friend was asked the following question: what's the difference between object language and object-oriented language? It's a little unintelligible question. What does term «object language» correspond to? Does that mean «pure» object-oriented language, like the Wikipedia article says: Languages called "pure" OO languages, because everything in them is treated consistently as an object, from primitives such as characters and punctuation, all the way up to whole classes, prototypes, blocks, modules, etc. They were designed specifically to facilitate, even enforce, OO methods. Examples: Smalltalk, Eiffel, Ruby, JADE, VB.NET.

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• Is there any difference in which order I createCriteria and beginTransaction using Hibernate?

  - by user2519543

  Just wondering is there any difference when I beginTransaction [org.hibernate] before or after creating Criteria/Query etc.? example 1: ... Transaction tx= session.beginTransaction(); Criteria c = session.createCriteria(class); result = c.uniqueResult(); tx.commit(); ... example 2: ... Criteria c = session.createCriteria(class); Transaction tx= session.beginTransaction(); result = c.uniqueResult(); tx.commit(); ... Thanks.

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• (C++) What's the difference between these overloaded operator functions?

  - by cv3000

  What is the difference between these two ways of overloading the != operator below. Which is consider better? Class Test { ...// private: int iTest public: BOOL operator==(const &Test test) const; BOOL operator!=(const &Test test) const; } BOOL operator==(const &Test test) const { return (iTest == test.iTest); } //overload function 1 BOOL Test::operator!=(const &Test test) const { return !operator==(test); } //overload function 2 BOOL Test::operator!=(const &Test test) const { return (iTest != test.iTest); } I've just recently seen function 1's syntax for calling a sibling operator function and wonder if writing it that way provides any benefits.

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• What difference does it make to use several script blocks on a web page?

  - by Jan Aagaard

  What difference does it make to use more than one script block on a web page? I have pasted in the standard code for including Google Analytics as an example, and I have seen the same pattern used in other places. Why is this code separated into two separate script blocks instead of just using a single one? <script type="text/javascript"> var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); </script> <script type="text/javascript"> try{ var pageTracker = _gat._getTracker("UA-xxxxxx-x"); pageTracker._trackPageview(); } catch(err) {} </script>

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• C++ is there a difference between assignment inside a pass by value and pass by reference function?

  - by Rémy DAVID

  Is there a difference between foo and bar: class A { Object __o; void foo(Object& o) { __o = o; } void bar(Object o) { __o = o; } } As I understand it, foo performs no copy operation on object o when it is called, and one copy operation for assignment. Bar performs one copy operation on object o when it is called and another one for assignment. So I can more or less say that foo uses 2 times less memory than bar (if o is big enough). Is that correct ? Is it possible that the compiler optimises the bar function to perform only one copy operation on o ? i.e. makes __o pointing on the local copy of argument o instead of creating a new copy?

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• What is the difference between as="element()+" and as="element()*" in XSL?

  - by Rachel

  What is the difference between using as="element(data)+" and as="element(data)" in xsl:variable. The below XSL solution works if use "+" but not when i use "". Can some one clarify. XSL code: <xsl:variable name="insert-data" as="element(data)+"> <xsl:for-each select="$insert-file/insert-data/data"> <xsl:sort select="xsd:integer(@index)"/> <xsl:variable name="index" select="xsd:integer(@index)" /> <xsl:variable name="nodeName" select="@nodeName" /> <data nodeName="{$nodeName}" index="{@index}" text-id="{$main-root/*//*[@id=$nodeName]/text()[sum((preceding::text(), .)/string-length(.)) ge $index]/generate-id(.)}"> <xsl:copy-of select="node()"/> </data> </xsl:for-each>

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• Why There is a difference between assembly languages like Windows, Linux ?

  - by mcaaltuntas

  I am relatively new to all this low level stuff,assembly language.. and want to learn more detail. Why there is a difference between Linux, Windows Assembly languages? As I understand when I compile a C code Operating system does not really produce pure machine or assembly code, it produces OS dependent binary code.But why ? For example when I use a x86 system, CPU only understands x86 ASM am I right?.So Why we dont write pure x86 assembly code and why there are different assembly variations based on Operating system? If we would write pure ASM or OS produce pure ASM there wouldn't be binary compatilibty issues between Operating systems or Not ? I am really wondering all reasons behind them. Any detailed answer, article, book would be great. Thanks.

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• Is there a semantic difference <span>'s and <div>'s?

  - by DavidR

  I know when coding HTML, I'm supposed to keep semantics in mind, e.g., h1 needs to be a main header, h2 needs to be a subheader, tables need to be tables, use <em> for emphasis instead of <i>, etc. Is there a proper difference between divs and spans except one is a block and the other is in-line? When I was learning I was told that <span>'s were for styling text mid-line. If I had a small blurb of text that I needed positioned at a certain point in my webpage, one that doesn't warrent a <p> tag, would I use a span should I stick with div's? What if that text needs to cover two lines (i.e., it needs a width) if it contains nothing but text, what should I use?

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• Is there a difference between NSString compare: and isEqual(ToString): ?

  - by frenetisch applaudierend

  Occasionally I find code which tests if two NSStrings are the same like this: if ([str1 compare:str2] == NSOrderedSame) { // Do something } Now, I believe this is less readable than using isEqualToString: and it also has some nasty side effects, like if str1 == nil the if(..) evaluates to true, or when str2 == nil havoc might break upon us according to the Apple docs. But before I crusade against those statements in my companys code, I wanted to make sure I didn't miss some important point. So my question basically boils down to: Is there any difference between a compare: to NSOrderedSame and isEqual:?

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• What's the Difference Between These Two Ruby Class Initialaztion Definitions?

  - by michaelmichael

  I'm working through a book on Ruby, and the author used a slightly different form for writing a class initialization definition than he has in previous sections of the book. It looks like this: class Ticket attr_accessor :venue, :date def initialize(venue, date) self.venue = venue self.date = date end end In previous sections of the book, it would've been defined like this: class Ticket attr_accessor :venue, :date def initialize(venue, date) @venue = venue @date = date end end Is there any functional difference between using the setter method, as in the first example vs. using the instance variable in the second? They both seem to work. Even mixing them up seems to work: class Ticket attr_accessor :venue, :date def initialize(venue, date) @venue = venue self.date = date end end

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• What's the Difference Between These Two Ruby Class Initialization Definitions?

  - by michaelmichael

  I'm working through a book on Ruby, and the author used a slightly different form for writing a class initialization definition than he has in previous sections of the book. It looks like this: class Ticket attr_accessor :venue, :date def initialize(venue, date) self.venue = venue self.date = date end end In previous sections of the book, it would've been defined like this: class Ticket attr_accessor :venue, :date def initialize(venue, date) @venue = venue @date = date end end Is there any functional difference between using the setter method, as in the first example, vs. using the instance variable as in the second? They both seem to work. Even mixing them up works: class Ticket attr_accessor :venue, :date def initialize(venue, date) @venue = venue self.date = date end end

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• Percentage difference between different values in the same keys of two different arrays.

  - by Paul

  Hey. I'm looking for a solution to this problem. I got 2 arrays, like this: array(2) { [20100526]=> array(1) { ["ga:pageviews"]=> string(5) "19088" } [20100527]=> array(1) { ["ga:pageviews"]=> string(5) "15566" } } array(2) { [20100526]=> array(1) { ["ga:pageviews"]=> string(5) "12043" } [20100527]=> array(1) { ["ga:pageviews"]=> string(5) "11953" } } Now I'd like to create a new array, with the % difference between the values per key. Would be something like this: array(2) { [20100526]=> array(1) { ["ga:pageviews"]=> string(5) "88,23" } [20100527]=> array(1) { ["ga:pageviews"]=> string(5) "74,54" } } Can anyone help me how to create that array?

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• What's the difference between Path and Polygon control? + issues when designing custom drawing user

  - by tomo

  I'm starting to design a custom control with rather complex drawing. It will be a kind of chart (a kind of radar chart). It will be composed of a few axises with labels, line-regions (like spider-network) and filled shapes. The main question is what's the difference between using Path control and Polygon control? What's better to use here? The goal is to prepare control with minimal amount of c# and try to do as much as possible in xaml / binding. The next important requirement is that control should resize to parent containers' width - if possible without any long recalulations in c#.

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• What is the difference between binding data in data grid view methods ??

  - by Ashish

  What is the difference between binding data in data grid view methods ?? <ItemTemplate> <asp:LinkButton ID="lnkBtnUserName" runat="server" Text='<%# DataBinder.Eval(Container.DataItem,"UserFirstName")%>' CommandArgument='<%# Eval("UserID") %>' OnClick="lnkBtnUserName_Click" /> </ItemTemplate> and this second one <asp:TemplateField HeaderText="Employee ID"> <ItemTemplate> <asp:Label ID="lblempid" runat="server" Text='<%# Bind("EmpId.EmpId") %>'></asp:Label> </ItemTemplate> </asp:TemplateField> means in method 1 Text='<%# DataBinder.Eval(Container.DataItem,"UserFirstName")%>' CommandArgument='<%# Eval("UserID") %>' method 2 Text='<%# Bind("EmpId.EmpId") also explain use one this CommandArgument='<%# Eval("UserID") in 1st one ????

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• Difference between Class Abstraction and Object Interfaces in PHP?

  - by Mark Tomlin

  What is the difference between a Class Abstraction and an Object Interfaces in PHP? I ask because, I don't really see the point to both of them, they both do the same thing! So, what are the advantages of disadvantages using both against one or the other? Class Abstraction: abstract class aClass { // Force extending class to define these methods abstract public function setVariable($name, $var); abstract public function getHtml($template); } Object Interface: interface iClass { // Force impementing class to define these methods public function setVariable($name, $var); public function getHtml($template); }

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• what is the difference between static class and normal class?

  - by Phsika

  when i prefer static or normal class? Or what is the difference between them? using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace staticmethodlar { class Program { static void Main(string[] args) { SinifA.method1(); } } static class SinifA { public static void method1() { Console.WriteLine("Deneme1"); } } public static class SinifB { public static void method2() { Console.WriteLine("Deneme2"); } } public class sinifC { public void method3() { Console.WriteLine("Deneme3"); } } public class sinifD : sinifC { void method4() { Console.WriteLine("Deneme4"); } sinifC sinifc = new sinifC(); // i need to use it:) } }

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• Jython: Is there any difference between adding to sys.path vs passing -D?

  - by trinth

  I have a python application that is trying to load some Java libraries (specifically Axis2 web services). When I add the necessary jars in Eclipse via PyDev Project Source Folders, everything seems to work fine. However, I want to be able to do this at run time by adding to sys.path, but then my application doesn't seem to work. In both cases I can load the jars just fine, but something must be different for there to be different results. My question is, is there a difference between adding jars via the sys.path at run time with sys.path.append() versus passing -D to the jython interpreter?

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• Whats the difference between a C++ and a Cocoa Project in Xcode?

  - by david

  I need to work with TagLib for my project. I've created a framework (and I tried using it as a lib) but the compiler cannot find #include < strings on compiling (No such file or Directory). I've created a test C++ project and it #includes < strings just fine. I've looked at the project settings and I cannot find a difference between them. But the standard cocoa projects obviously so not have the search path set to include C++ libraries (Or am I completely getting it wrong?). I've searched for a solution but no one else seems to have run into this problem.

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• What is the difference between these two ways of creating NSStrings?

  - by adame

  NSString *myString = @"Hello"; NSString *myString = [NSString stringWithString:@"Hello"]; I understand that using method (1) creates a pointer to a string literal that is defined as static memory (and cannot be deallocated) and that using (2) creates an NSString object that will be autoreleased. Is using method (1) bad? What are the major differences? Is there any instances where you would want to use (1)? Is there a performance difference? P.S. I have searched extensively on Stack Overflow and while there are questions on the same topic, none of them have answers to the questions I have posted above.

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• Is there any difference in the implementation of these three validation methods?

  - by dontWatchMyProfile

  Core Data is calling these methods in certain situations: - (BOOL)validateForInsert:(NSError **)outError; - (BOOL)validateForUpdate:(NSError **)outError; - (BOOL)validateForDelete:(NSError **)outError; I wonder if they're doing anything different, or if they're essentially doing the exact same things. As far as I know, these methods call the -validateValue:forKey:error: method once for every property. The only difference I can imagine is in the .validateForDelete: method. I see no reason why to validate an object when it shall be deleted, except for applying delete rules, probably only in the case of the DENY rule.

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• (iphone) Does it make difference to provide more images when the object is moving in a straight line?

  - by Eugene

  Hi. Among many animation scenarios, there are times when I want an object to move a straight line then change direction, move another straight line and so forth. Assuming I would use either UIImageView or CABasicAnimation with image arrays. Does it make difference to provide more images when the object is moving in a straight line? For example, point1 ---------point2 ------- point3 (all points are in a straight line) Providing an image at point2 to UIImageView or CABasicAnimation, gives any better animation result, assuming I don't need to change the animation speed along the course? If I were flashing each image myself, yes it would make the animation look smooth, but I'm giving the images to UIImageView/CABasicAnimation, and wonder what they do. Thank you

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• How to check if the sum of some records equals the difference between two other records in t-sql?

  - by Dan Appleyard

  I have a view that contains bank account activity. ACCOUNT BALANCE_ROW AMOUNT SORT_ORDER 111 1 0.00 1 111 0 10.00 2 111 0 -2.50 3 111 1 7.50 4 222 1 100.00 5 222 0 25.00 6 222 1 125.00 7 ACCOUNT = account number BALANCE_ROW = either starting or ending balance would be 1, otherwise 0 AMOUNT = the amount SORT_ORDER = simple order to return the records in the order of start balance, activity, and end balance I need to figure out a way to see if the sum of the non balance_row rows equal the difference between the ending balance and the starting balance. The result for each account (1 for yes, 0 for no) would be simply added to the resulting result set. Example: Account 111 had a starting balance of 0.00. There were two account activity records of 10.00 and -2.5. That resulted in the ending balance of 7.50. I've been playing around with temp tables, but I was not sure if there is a more efficient way of accomplishing this. Thanks for any input you may have!

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