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  • What can I do with dynamic typing that I can not do with static typing

    - by Justin984
    I've been using python for a few days now and I think I understand the difference between dynamic and static typing. What I don't understand is why it's useful. I keep hearing about its "flexibility" but it seems like it just moves a bunch of compile time checks to runtime, which means more unit tests. This seems like an awfully big tradeoff to make for small advantages like readability and "flexibility". Can someone provide me with a real world example where dynamic typing allows me to do something I can't do with static typing?

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  • What functionality does dynamic typing allow?

    - by Justin984
    I've been using python for a few days now and I think I understand the difference between dynamic and static typing. What I don't understand is under what circumstances it would be preferred. It is flexible and readable, but at the expense of more runtime checks and additional required unit testing. Aside from non-functional criteria like flexibility and readability, what reasons are there to choose dynamic typing? What can I do with dynamic typing that isn't possible otherwise? What specific code example can you think of that illustrates a concrete advantage of dynamic typing?

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  • Access static method from non static class possible in java and not in c#

    - by sagar_kool
    Access static method from non static class with object. It is not possible in C#. Where it is done by JAVA. How it works? example of java /** * Access static member of the class through object. */ import java.io.*; class StaticMemberClass { // Declare a static method. public static void staticDisplay() { System.out.println("This is static method."); } // Declare a non static method. public void nonStaticDisplay() { System.out.println("This is non static method."); } } class StaticAccessByObject { public static void main(String[] args) throws IOException { // call a static member only by class name. StaticMemberClass.staticDisplay(); // Create object of StaticMemberClass class. StaticMemberClass obj = new StaticMemberClass(); // call a static member only by object. obj.staticDisplay(); // accessing non static method through object. obj.nonStaticDisplay(); } } Output of the program: This is static method. This is static method. This is non static method. How to do this in C#? thanks in advance..

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  • Static/Dynamic vs Strong/Weak

    - by Dan Revell
    I see these terms banded around all over the place in programming and I have a vague notion of what they mean. A search shows me that such things have been asked all over stack overflow in fact. As far as I'm aware Static/Dynamic typing in languages is subtly different to Strong/Weak typing but what that difference is eludes me. Different sources seem to use different different meanings or even use the terms interchangeably. I can't find somewhere that talks about both and actually spells out the difference. What would be nice is if someone could please spell this out clearly here for me and the rest of the world.

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  • What is the best keyboard for typing speed (not layouts)

    - by Gapton
    So I am a programmer, and I like playing typing speed games. My typing speed is, for common English words, 85 to 90 wpm, max 95. I type on various devices, my laptop, desktop, office pc.... they all have slightly different keyboards. Being a curious programmer, I wonder what types of keyboard is used for the highest possible typing speed. Or let me phrase it in another way, what is the type of keyboards that people use in typing speed contest? Here is something I know that I feel like I can share: It must be a wired keyboard, I can feel the lag as I am typing this on my wireless keyboard, even if it is a slightly more expensive model which claims to have zero lag. I know people prefer a mechanical keyboard, for the hepatic feedback, however I have not tried one. It lasts longer and is noisy, it also does not have the problem of normal keyboards where you press many keys at a time the signals will get all jammed and the computer will only receive one or two keys. I personally prefer those "thin profile" keyboards. I type a lot, and 95 wpm put me in the top 5%, this is of course just on a gaming site. However when I type on the fat keyboards, my fingers have to travel a much longer distance before the keys actually click. This is where I find myself typing much faster with those thin profile keyboards found on my laptop. Because my fingers only hover on the keys and I only need to press a short distance, each stroke takes less force and light rapid strokes is what makes me type fast. When I type on a fat keyboard, I was forced to use heavy strokes, and this slows me down. There must be some people out there who are keyboard scientists, who actually do experiments and user tests with different setups. It would be interesting to understand more about the things we use everyday for not just work but a majority of our communications. P.S. this is about hardware and not about switching keyboard layouts to dvorak

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  • Static and Non Static Method Intercall in Java

    - by Vishal
    I am clearing my concepts on Java. My knowledge about Java is on far begineer side, so kindly bear with me. I am trying to understand static method and non static method intercalls. I know -- Static method can call another static method simply by its name within same class. Static method can call another non staic method of same class only after creating instance of the class. Non static method can call another static method of same class simply by way of classname.methodname - No sure if this correct ? My Question is about non static method call to another non staic method of same class. In class declaration, when we declare all methods, can we call another non static method of same class from a non static class ? Please explain with example. Thank you.

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  • Java: static-non-static-this problem

    - by HH
    $ javac TestFilter.java TestFilter.java:19: non-static variable this cannot be referenced from a static context for(File f : file.listFiles(this.filterFiles)){ ^ 1 error $ sed -i 's@this@TestFilter@g' TestFilter.java $ javac TestFilter.java $ java TestFilter file1 file2 file3 TestFilter.java import java.io.*; import java.util.*; public class TestFilter { private static final FileFilter filterFiles; // STATIC! static{ filterFiles = new FileFilter() { // Not Static below. When static, an error: // "accept(java.io.File) in cannot implement // accept(java.io.File) in java.io.FileFilter; // overriding method is static" // // I tried to solve by the change the problem at the bottom. public boolean accept(File file) { return file.isFile(); } }; } // STATIC! public static void main(String[] args){ HashSet<File> files = new HashSet<File>(); File file = new File("."); // IT DID NOT WORK WITH "This" but with "TestFilter". // Why do I get the error with "This" but not with "TestFilter"? for(File f : file.listFiles(TestFilter.filterFiles)){ System.out.println(f.getName()); files.add(f); } } }

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  • trouble accessing non-static functions from static functions in AS3

    - by Dogmatixed
    I have a class containing, among other things, a drop down menu. With the aim of saving space, and since the contents of the menu will never change, I've made a static DataProvider for the whole class that populates each instances menu. I was hoping to populate the list with actual functions like so: tmpArr.push({label:"Details...", funct:openDetailsMenu, args:""}); and then assign tmpArr to the DataProvider. Because the DataProvider is static the function that contains that code also needs to be static, but the functions in the array are non-static. At first it didn't seem like a problem, because when the user clicks on a menu item the drop down menu can call a non-static "executeFunction(funct, args)" on its parent. However, when I try to compile, the static function setting up the DataProvider it can't find the non-static functions being passed. If the compiler would just trust me the code would work fine! The simple solution is to just pass strings and use a switch statement to call functions based on that, but that's big, ugly, inelegant, and difficult to maintain, especially if something inherits from this class. The simpler solution is to just make the DataProvider non-static, but I'm wondering if anyone else has a good way of dealing with this? Making the static function able to see its non-static brethren? Thanks.

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  • Static class vs Singleton class in C# [closed]

    - by Floradu88
    Possible Duplicate: What is the difference between all-static-methods and applying a singleton pattern? I need to make a decision for a project I'm working of whether to use static or singleton. After reading an article like this I am inclined to use singleton. What is better to use static class or singleton? Edit 1 : Client Server Desktop Application. Please provide code oriented solutions.

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  • Is there a compiled* programming language with dynamic, maybe even weak typing?

    - by sub
    I wondered if there is a programming language which compiles to machine code/binary (not bytecode then executed by a VM, that's something completely different when considering typing) that features dynamic and/or weak typing, e.g: Think of a compiled language where: Variables don't need to be declared Variables can be created doing runtime Functions can return values of different types Questions: Is there such a programming language? (Why) not? I think that a dynamically yet strong typed, compiled language would really sense, but is it possible?

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  • C++: Retriving values of static const variables at a constructor of a static variable

    - by gilbertc
    I understand that the code below would result segmentation fault because at the cstr of A, B::SYMBOL was not initialized yet. But why? In reality, A is an object that serves as a map that maps the SYMBOLs of classes like B to their respective IDs. C holds this map(A) static-ly such that it can provide the mapping as a class function. The primary function of A is to serve as a map for C that initializes itself at startup. How should I be able to do that without segmentation fault, provided that I can still use B::ID and B::SYMBOL in the code (no #define pls)? Thanks! Gil. class A { public: A() { std::cout<<B::ID<<std::endl; std::cout<<B::SYMBOL<<std::endl; } }; class B { public: static const int ID; static const std::string SYMBOL; } const int B::ID = 1; const std::string B::SYMBOL = "B"; class C { public: static A s_A; }; A C::s_A; int main(int c, char** p) { }

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  • Is duck typing a subset of polymorphism

    - by Raynos
    From Polymorphism on WIkipedia In computer science, polymorphism is a programming language feature that allows values of different data types to be handled using a uniform interface. From duck typing on Wikipedia In computer programming with object-oriented programming languages, duck typing is a style of dynamic typing in which an object's current set of methods and properties determines the valid semantics, rather than its inheritance from a particular class or implementation of a specific interface. My interpretation is that based on duck typing, the objects methods/properties determine the valid semantics. Meaning that the objects current shape determines the interface it upholds. From polymorphism you can say a function is polymorphic if it accepts multiple different data types as long as they uphold an interface. So if a function can duck type, it can accept multiple different data types and operate on them as long as those data types have the correct methods/properties and thus uphold the interface. (Usage of the term interface is meant not as a code construct but more as a descriptive, documenting construct) What is the correct relationship between ducktyping and polymorphism ? If a language can duck type, does it mean it can do polymorphism ?

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  • Fake ISAPI Handler to serve static files with extention that are rewritted by url rewriter

    - by developerit
    Introduction I often map html extention to the asp.net dll in order to use url rewritter with .html extentions. Recently, in the new version of www.nouvelair.ca, we renamed all urls to end with .html. This works great, but failed when we used FCK Editor. Static html files would not get serve because we mapped the html extension to the .NET Framework. We can we do to to use .html extension with our rewritter but still want to use IIS behavior with static html files. Analysis I thought that this could be resolve with a simple HTTP handler. We would map urls of static files in our rewriter to this handler that would read the static file and serve it, just as IIS would do. Implementation This is how I coded the class. Note that this may not be bullet proof. I only tested it once and I am sure that the logic behind IIS is more complicated that this. If you find errors or think of possible improvements, let me know. Imports System.Web Imports System.Web.Services ' Author: Nicolas Brassard ' For: Solutions Nitriques inc. http://www.nitriques.com ' Date Created: April 18, 2009 ' Last Modified: April 18, 2009 ' License: CPOL (http://www.codeproject.com/info/cpol10.aspx) ' Files: ISAPIDotNetHandler.ashx ' ISAPIDotNetHandler.ashx.vb ' Class: ISAPIDotNetHandler ' Description: Fake ISAPI handler to serve static files. ' Usefull when you want to serve static file that has a rewrited extention. ' Example: It often map html extention to the asp.net dll in order to use url rewritter with .html. ' If you want to still serve static html file, add a rewritter rule to redirect html files to this handler Public Class ISAPIDotNetHandler Implements System.Web.IHttpHandler Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest ' Since we are doing the job IIS normally does with html files, ' we set the content type to match html. ' You may want to customize this with your own logic, if you want to serve ' txt or xml or any other text file context.Response.ContentType = "text/html" ' We begin a try here. Any error that occurs will result in a 404 Page Not Found error. ' We replicate the behavior of IIS when it doesn't find the correspoding file. Try ' Declare a local variable containing the value of the query string Dim uri As String = context.Request("fileUri") ' If the value in the query string is null, ' throw an error to generate a 404 If String.IsNullOrEmpty(uri) Then Throw New ApplicationException("No fileUri") End If ' If the value in the query string doesn't end with .html, then block the acces ' This is a HUGE security hole since it could permit full read access to .aspx, .config, etc. If Not uri.ToLower.EndsWith(".html") Then ' throw an error to generate a 404 Throw New ApplicationException("Extention not allowed") End If ' Map the file on the server. ' If the file doesn't exists on the server, it will throw an exception and generate a 404. Dim fullPath As String = context.Server.MapPath(uri) ' Read the actual file Dim stream As IO.StreamReader = FileIO.FileSystem.OpenTextFileReader(fullPath) ' Write the file into the response context.Response.Output.Write(stream.ReadToEnd) ' Close and Dipose the stream stream.Close() stream.Dispose() stream = Nothing Catch ex As Exception ' Set the Status Code of the response context.Response.StatusCode = 404 'Page not found ' For testing and bebugging only ! This may cause a security leak ' context.Response.Output.Write(ex.Message) Finally ' In all cases, flush and end the response context.Response.Flush() context.Response.End() End Try End Sub ' Automaticly generated by Visual Studio ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable Get Return False End Get End Property End Class Conclusion As you see, with our static files map to this handler using query string (ex.: /ISAPIDotNetHandler.ashx?fileUri=index.html) you will have the same behavior as if you ask for the uri /index.html. Finally, test this only in IIS with the html extension map to aspnet_isapi.dll. Url rewritting will work in Casini (Internal Web Server shipped with Visual Studio) but it’s not the same as with IIS since EVERY request is handle by .NET. Versions First release

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  • Can static and dynamically typed languages be seen as different tools for different types of jobs?

    - by Erik Reppen
    Yes, similar questions have been asked but always with the aim of finding out 'which one is better.' I'm asking because I came up as a dev primarily in JavaScript and don't really have any extensive experience writing in statically typed languages. In spite of this I definitely see value in learning C for handling demanding operations at lower levels of code (which I assume has a lot to do with static vs dynamic at the compiler level), but what I'm trying to wrap my head around is whether there are specific project contexts (maybe certain types of dynamic data-intensive operations?) involving things other than performance where it makes a lot more sense to go with Java or C# vs. something like Python.

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  • Static vs Singleton in C# (Difference between Singleton and Static)

    - by Jalpesh P. Vadgama
    Recently I have came across a question what is the difference between Static and Singleton classes. So I thought it will be a good idea to share blog post about it.Difference between Static and Singleton classes:A singleton classes allowed to create a only single instance or particular class. That instance can be treated as normal object. You can pass that object to a method as parameter or you can call the class method with that Singleton object. While static class can have only static methods and you can not pass static class as parameter.We can implement the interfaces with the Singleton class while we can not implement the interfaces with static classes.We can clone the object of Singleton classes we can not clone the object of static classes.Singleton objects stored on heap while static class stored in stack.more at my personal blog: dotnetjalps.com

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  • Which tips helped you learn touch-typing? [closed]

    - by julien
    I've been learning touch-typing for about two weeks now, and I'm really commited to mastering this skill. Eventhough I'm doing ok with prose already, I'm struggling with programming syntax and even more with keybindings. Those stray you away from the home row more than regular words, and aren't as easy to practice. So I often hunt and peck in order to just get it out, but when reverting to old habits like this, I find it hard to get back into the touch-typing mindframe quickly. One little trick that has helped me so far when getting lost is to reposition every finger on its home row key, and mentally visualize the layout bias of the keyboard, ie the backslash kind of alignment of key columns. It's hard to describe though and probably a bit weird... Hope you guys have better tips !

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  • Static objects and concurrency in a web application

    - by Ionut
    I'm developing small Java Web Applications on Tomcat server and I'm using MySQL as my database. Up until now I was using a connection singleton for accessing the database but I found out that this will ensure just on connection per Application and there will be problems if multiple users want to access the database in the same time. (They all have to make us of that single Connection object). I created a Connection Pool and I hope that this is the correct way of doing things. Furthermore it seems that I developed the bad habit of creating a lot of static object and static methods (mainly because I was under the wrong impression that every static object will be duplicated for every client which accesses my application). Because of this all the Service Classes ( classes used to handle database data) are static and distributed through a ServiceFactory: public class ServiceFactory { private static final String JDBC = "JDBC"; private static String impl; private static AccountService accountService; private static BoardService boardService; public static AccountService getAccountService(){ initConfig(); if (accountService == null){ if (impl.equalsIgnoreCase(JDBC)){ accountService = new JDBCAccountService(); } } return accountService; } public static BoardService getBoardService(){ initConfig(); if (boardService == null){ if (impl.equalsIgnoreCase(JDBC)){ boardService = new JDBCBoardService(); } } return boardService; } private static void initConfig(){ if (StringUtil.isEmpty(impl)){ impl = ConfigUtil.getProperty("service.implementation"); // If the config failed initialize with standard if (StringUtil.isEmpty(impl)){ impl = JDBC; } } } This was the factory class which, as you can see, allows just one Service to exist at any time. Now, is this a bad practice? What happens if let's say 1k users access AccountService simultaneously? I know that all this questions and bad practices come from a bad understanding of the static attribute in a web application and the way the server handles this attributes. Any help on this topic would be more than welcomed. Thank you for your time!

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  • Python Forgiveness vs. Permission and Duck Typing

    - by darkfeline
    In Python, I often hear that it is better to "beg forgiveness" (exception catching) instead of "ask permission" (type/condition checking). In regards to enforcing duck typing in Python, is this try: x = foo.bar except AttributeError: pass else: do(x) better or worse than if hasattr(foo, "bar"): do(foo.bar) else: pass in terms of performance, readability, "pythonic", or some other important factor?

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  • Don't Use Static? [closed]

    - by Joshiatto
    Possible Duplicate: Is static universally “evil” for unit testing and if so why does resharper recommend it? Heavy use of static methods in a Java EE web application? I submitted an application I wrote to some other architects for code review. One of them almost immediately wrote me back and said "Don't use "static". You can't write automated tests with static classes and methods. "Static" is to be avoided." I checked and fully 1/4 of my classes are marked "static". I use static when I am not going to create an instance of a class because the class is a single global class used throughout the code. He went on to mention something involving mocking, IOC/DI techniques that can't be used with static code. He says it is unfortunate when 3rd party libraries are static because of their un-testability. Is this other architect correct?

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  • How can i find touch typing lesson for words with middle row only

    - by user1838032
    I am learning touch typing. i want practice step by step. Is there any site where i can have the options of the keys to select and then have lesson for those slected keys only. I means i select the keys from keyboard and then system prepares the lesson for only those keys with random combination. Current i want to practice keys asdf gh jkl; Now i am not able to find practice for that whole row only. i mena random combinatins

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  • Does weak typing offer any advantages?

    - by sub
    Don't confuse this with static vs. dynamic typing! You all know JavaScripts/PHPs infamous type systems: PHP example: echo "123abc"+2; // 125 - the reason for this is explained // in the PHP docs but still: This hurts echo "4"+1; // 5 - Oh please echo "ABC"*5; // 0 - WTF // That's too much, seriously now. // This here might be actually a use for weak typing, but no - // it has to output garbage. JavaScript example: // A good old JavaScript, maybe you'll do better? alert("4"+1); // 51 - Oh come on. alert("abc"*3); // NaN - What the... // Have your creators ever heard of the word "consistence"? Python example: # Python's type system is actually a mix # It spits errors on senseless things like the first example below AND # allows intelligent actions like the second example. >>> print("abc"+1) Traceback (most recent call last): File "<pyshell#2>", line 1, in <module> print("abc"+1) TypeError: Can't convert 'int' object to str implicitly >>> print("abc"*5) abcabcabcabcabc Ruby example: puts 4+"1" // Type error - as supposed puts "abc"*4 // abcabcabcabc - makes sense After these examples it should be clear that PHP/JavaScript probably have the most inconsistent type systems out there. This is a fact and really not subjective. Now when having a closer look at the type systems of Ruby and Python it seems like they are having a much more intelligent and consistent type system. I think these examples weren't really necessary as we all know that PHP/JavaScript have a weak and Python/Ruby have a strong type system. I just wanted to mention why I'm asking this. Now I have two questions: When looking at those examples, what are the advantages of PHPs and JavaScripts type systems? I can only find downsides: They are inconsistent and I think we know that this is not good Types conversions are hardly controllable Bugs are more likely to happen and much harder to spot Do you prefer one of the both systems? Why? Personally I have worked with PHP, JavaScript and Python so far and must say that Pythons type system has really only advantages over PHPs and JavaScripts. Does anybody here not think so? Why then?

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  • Simulating aspects of static-typing in a duck-typed language

    - by Mike
    In my current job I'm building a suite of Perl scripts that depend heavily on objects. (using Perl's bless() on a Hash to get as close to OO as possible) Now, for lack of a better way of putting this, most programmers at my company aren't very smart. Worse, they don't like reading documentation and seem to have a problem understanding other people's code. Cowboy coding is the game here. Whenever they encounter a problem and try to fix it, they come up with a horrendous solution that actually solves nothing and usually makes it worse. This results in me, frankly, not trusting them with code written in duck typed language. As an example, I see too many problems with them not getting an explicit error for misusing objects. For instance, if type A has member foo, and they do something like, instance->goo, they aren't going to see the problem immediately. It will return a null/undefined value, and they will probably waste an hour finding the cause. Then end up changing something else because they didn't properly identify the original problem. So I'm brainstorming for a way to keep my scripting language (its rapid development is an advantage) but give an explicit error message when an an object isn't used properly. I realize that since there isn't a compile stage or static typing, the error will have to be at run time. I'm fine with this, so long as the user gets a very explicit notice saying "this object doesn't have X" As part of my solution, I don't want it to be required that they check if a method/variable exists before trying to use it. Even though my work is in Perl, I think this can be language agnostic.

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  • .htaccess to block by file name possible?

    - by Tiffany Walker
    I have a bunch of files that are secure_xxxxxx.php. Is there a way to use .htaccess to block access to all the secure_* php files based on IP? EDIT: I've tried but I get 500 errors <FilesMatch "^secure_.*\.php$"> order deny all deny from all allow from my ip here </FilesMatch> Don't see any errors in apache error logs either httpd -M Loaded Modules: core_module (static) authn_file_module (static) authn_default_module (static) authz_host_module (static) authz_groupfile_module (static) authz_user_module (static) authz_default_module (static) auth_basic_module (static) include_module (static) filter_module (static) log_config_module (static) logio_module (static) env_module (static) expires_module (static) headers_module (static) setenvif_module (static) version_module (static) proxy_module (static) proxy_connect_module (static) proxy_ftp_module (static) proxy_http_module (static) proxy_scgi_module (static) proxy_ajp_module (static) proxy_balancer_module (static) ssl_module (static) mpm_prefork_module (static) http_module (static) mime_module (static) dav_module (static) status_module (static) autoindex_module (static) asis_module (static) info_module (static) suexec_module (static) cgi_module (static) dav_fs_module (static) negotiation_module (static) dir_module (static) actions_module (static) userdir_module (static) alias_module (static) rewrite_module (static) so_module (static) fastinclude_module (shared) auth_passthrough_module (shared) bwlimited_module (shared) frontpage_module (shared) suphp_module (shared) Syntax OK

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