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  • x86 CMP Instruction Difference

    - by Pindatjuh
    Question What is the (non-trivial) difference between the following two x86 instructions? 39 /r CMP r/m32,r32 Compare r32 with r/m32 3B /r CMP r32,r/m32 Compare r/m32 with r32 Background I'm building a Java assembler, which will be used by my compiler's intermediate language to produce Windows-32 executables. Currently I have following code: final ModelBase mb = new ModelBase(); // create new memory model mb.addCode(new Compare(Register.ECX, Register.EAX)); // add code mb.addCode(new Compare(Register.EAX, Register.ECX)); // add code final FileOutputStream fos = new FileOutputStream(new File("test.exe")); mb.writeToFile(fos); fos.close(); To output a valid executable file, which contains two CMP instruction in a TEXT-section. The executable outputted to "text.exe" will do nothing interesting, but that's not the point. The class Compare is a wrapper around the CMP instruction. The above code produces (inspecting with OllyDbg): Address Hex dump Command 0040101F |. 3BC8 CMP ECX,EAX 00401021 |. 3BC1 CMP EAX,ECX The difference is subtle: if I use the 39 byte-opcode: Address Hex dump Command 0040101F |. 39C1 CMP ECX,EAX 00401021 |. 39C8 CMP EAX,ECX Which makes me wonder about their synonymity and why this even exists.

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  • Pros & Cons of Google App Engine

    - by Rishi
    Pros & Cons of Google App Engine [An Updated List 21st Aug 09] Help me Compile a List of all the Advantages & Disadvantages of Building an Application on the Google App Engine Pros: 1) No Need to buy Servers or Server Space (no maintenance). 2) Makes solving the problem of scaling much easier. Cons: 1) Locked into Google App Engine ?? 2)Developers have read-only access to the filesystem on App Engine. 3)App Engine can only execute code called from an HTTP request (except for scheduled background tasks). 4)Users may upload arbitrary Python modules, but only if they are pure-Python; C and Pyrex modules are not supported. 5)App Engine limits the maximum rows returned from an entity get to 1000 rows per Datastore call. 6)Java applications may only use a subset (The JRE Class White List) of the classes from the JRE standard edition. 7)Java applications cannot create new threads. Known Issues!! http://code.google.com/p/googleappengine/issues/list Hard limits Apps per developer - 10 Time per request - 30 sec Files per app - 3,000 HTTP response size - 10 MB Datastore item size - 1 MB Application code size - 150 MB Pro or Con? App Engine's infrastructure removes many of the system administration and development challenges of building applications to scale to millions of hits. Google handles deploying code to a cluster, monitoring, failover, and launching application instances as necessary. While other services let users install and configure nearly any *NIX compatible software, App Engine requires developers to use Python or Java as the programming language and a limited set of APIs. Current APIs allow storing and retrieving data from a BigTable non-relational database; making HTTP requests; sending e-mail; manipulating images; and caching. Most existing Web applications can't run on App Engine without modification, because they require a relational database.

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  • Submit information to url, but also open PDF

    - by Mad Ducky Digital Branding
    I have a client whose desire is to have her Wordpress blog show a MailChimp form on her home page as a gateway to a .pdf. I need the following behavior to occur when the user clicks "Submit": execute the included MailChimp's javascript file; this ensures the form was properly filled, and then performs the sign-up to the newsletter list (don't need help with this part) then show the user an informational PDF for download or viewing EDIT: The logical order was flipped from when I originally posted this. The script should execute, and only if the script gets executed properly should the PDF show to the user Note: My experience level with HTML and PHP is 3/4, and with JS I am 2/4 EDIT: (seems more like 1/4 at this point lol). If my research is correct, PHP (server-side language) would be used to do that which the client wants. Additional validation is not necessary beyond what MailChimp's script provides (it ensures that user has submitted a completed form) is not necessary in this case (the client says it's ok if the e-mail isn't valid at all). EDIT: Reworded this sentence from original post to be more clear The .pdf URL and content is static, and simply needs to be shown, not generated. ----RESEARCH---- I know that the Mailchimp form uses the following line to actually submit the information, but I want to do the action mentioned below, as well as open the aforementioned .pdf: <form action="http://*BLAH*.us2.list-manage.com/subscribe/post?u=*BLAHBLAH*&amp;id=*BLAHBLAHBLAH*" method="post" id="mc-embedded-subscribe-form" name="mc-embedded-subscribe-form" class="validate" target="_blank"> I am reading on other sites that I can conceivably point "action" to a .php file, but if there is a way to do this with javascript - since its using the .js file that I created for that already anyways, then I would be most happy. Barring that, I'll take what I can get.. ----SOLUTION?---- ...

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  • including tk.h and tcl.h in c program

    - by user362075
    hi, i am working on an ubuntu system. My aim is to basically make an IDE in C language using GUI tools from TCL/TK. I installed tcl 8.4, tk8.4, tcl8.4-dev, tk8.4-dev and have the tk.h and tcl.h headers file in my system. But, when I am running a basic hello world program it's showing a hell lot of errors. include "tk.h" include "stdio.h" void hello() { puts("Hello C++/Tk!"); } int main(int, char *argv[]) { init(argv[0]); button(".b") -text("Say Hello") -command(hello); pack(".b") -padx(20) -pady(6); } Some of the errors are tkDecls.h:644: error: expected declaration specifiers before ‘EXTERN’ /usr/include/libio.h:488: error: expected ‘)’ before ‘*’ token In file included from tk.h:1559, from new1.c:1: tkDecls.h:1196: error: storage class specified for parameter ‘TkStubs’ tkDecls.h:1201: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘attribute’ before ‘*’ token /usr/include/stdio.h:145: error: storage class specified for parameter ‘stdin’ tk.h:1273: error: declaration for parameter ‘Tk_PhotoHandle’ but no such parameter Can anyone please tell me how can I rectify these errors? Please help...

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  • including tk.h and tcl.h in c program

    - by user362075
    hi, i am working on an ubuntu system. My aim is to basically make an IDE in C language using GUI tools from TCL/TK. I installed tcl 8.4, tk8.4, tcl8.4-dev, tk8.4-dev and have the tk.h and tcl.h headers file in my system. But, when I am running a basic hello world program it's showing a hell lot of errors. include "tk.h" include "stdio.h" void hello() { puts("Hello C++/Tk!"); } int main(int, char *argv[]) { init(argv[0]); button(".b") -text("Say Hello") -command(hello); pack(".b") -padx(20) -pady(6); } Some of the errors are tkDecls.h:644: error: expected declaration specifiers before ‘EXTERN’ /usr/include/libio.h:488: error: expected ‘)’ before ‘*’ token In file included from tk.h:1559, from new1.c:1: tkDecls.h:1196: error: storage class specified for parameter ‘TkStubs’ tkDecls.h:1201: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘attribute’ before ‘*’ token /usr/include/stdio.h:145: error: storage class specified for parameter ‘stdin’ tk.h:1273: error: declaration for parameter ‘Tk_PhotoHandle’ but no such parameter Can anyone please tell me how can I rectify these errors? Please help...

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  • How can I write classes that don't rely on "global" variables?

    - by Joel
    When I took my first programming course in university, we were taught that global variables were evil & should be avoided at all cost (since you can quickly develop confusing and unmaintainable code). The following year, we were taught object oriented programming, and how to create modular code using classes. I find that whenever I work with OOP, I use my classes' private variables as global variables, i.e., they can be (and are) read and modified by any function within the class. This isn't really sitting right with me, as it seems to introduce the same problems global variables had in languages like C. So I guess my question is, how do I stop writing classes with "global" variables? Would it make more sense to pretend I'm writing in a functional language? By this I mean having all functions take parameters & return values instead of directly modifying class variables. If I need to set any fields, I can just take the output of the function and assign it instead of having the function do it directly. This seems like it might make more maintainable code, at least for larger classes. What's common practice? Thanks!

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  • Simulating pass by reference for an array in Java

    - by Leif Andersen
    I was wondering, in java, is it possible to in anyway, simulate pass by reference for an array? Yes, I know the language doesn't support it, but is there anyway I can do it. Say, for example, I want to create a method that reverses the order of all the elements in an array. (I know that this code snippet isn't the best example, as there is a better algorithms to do this, but this is a good example of the type of thing I want to do for more complex problems). Currently, I need to make a class like this: public static void reverse(Object[] arr) { Object[] tmpArr = new Object[arr.length]; count = arr.length - 1; for(Object i : arr) tmpArr[count--] = i; // I would like to do arr = tmpArr, but that will only make the shallow // reference tmpArr, I would like to actually change the pointer they passed in // Not just the values in the array, so I have to do this: count = arr.length - 1; for(Object i : tmpArr) arr[count--] = i; return; } Yes, I know that I could just swap the values until I get to the middle, and it would be much more efficient, but for other, more complex purposes, is there anyway that I can manipulate the actual pointer? Again, thank you.

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  • InternetExplorer.Application object and cookie container

    - by Darin Dimitrov
    I have the following console application written in VB.NET: Sub Main() Dim ie As Object = CreateObject("InternetExplorer.Application") ie.Visible = True ie.Navigate2("http://localhost:4631/Default.aspx") End Sub This program uses the InternetExplorer.Application automation object to launch an IE window and navigate a given url. The problem that I encountered is that even if I launch multiple instances of my application, the IE windows that are created with this method all share the same cookie container. Is there any parameter I could use specifying that a different cookie container is created for every window? This is the web page I used to test cookies: <%@ Page Language="C#" AutoEventWireup="true" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> protected void Page_Load(object sender, EventArgs e) { // Store something into the session in order to create the cookie Session["foo"] "bar"; Response.Write(Session.SessionID); } </script> <html xmlns="http://www.w3.org/1999/xhtml" > <body> <form id="form1" runat="server"></form> </body> </html>

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  • JSF ISO-8859-2 charset

    - by Vladimir
    Hi! I have problem with setting proper charset on my jsf pages. I use MySql db with latin2 (ISO-8859-2 charset) and latin2_croatian_ci collation. But, I have problems with setting values on backing managed bean properties. Page directive on top of my page is: <%@ page language="java" pageEncoding="ISO-8859-2" contentType="text/html; charset=ISO-8859-2" %> In head I included: <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-2"> And my form tag is: <h:form id="entityDetails" acceptcharset="ISO-8859-2"> I've created and registered Filter in web.xml with following doFilter method implementation: public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { request.setCharacterEncoding("ISO-8859-2"); response.setCharacterEncoding("ISO-8859-2"); chain.doFilter(request, response); } But, i.e. when I set managed bean property through inputText, all special (unicode) characters are replaced with '?' character. I really don't have any other ideas how to set charset to pages to perform well. Any suggestions? Thanks in advance.

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  • Display ñ on a C# .NET application

    - by mmr
    I have a localization issue. One of my industrious coworkers has replaced all the strings throughout our application with constants that are contained in a dictionary. That dictionary gets various strings placed in it once the user selects a language (English by default, but target languages are German, Spanish, French, Portuguese, Mandarin, and Thai). For our test of this functionality, we wanted to change a button to include text which has a ñ character, which appears both in Spanish and in the Arial Unicode MS font (which we're using throughout the application). Problem is, the ñ is appearing as a square block, as if the program did not know how to display it. When I debug into that particular string being read from disk, the debugger reports that character as a square block as well. So where is the failure? I think it could be in a few places: 1) Notepad may not be unicode aware, so the ñ displayed there is not the same as what vs2008 expects, and so the program interprets the character as a square (EDIT: notepad shows the same characters as vs; ie, they both show the ñ. In the same place.). 2) vs2008 can't handle ñ. I find that very, very hard to believe. 3) The text is read in properly, but the default font for vs2008 can't display it, which is why the debugger shows a square. 4) The text is not read in properly, and I should use something other than a regular StreamReader to get strings. 5) The text is read in properly, but the default String class in C# doesn't handle ñ well. I find that very, very hard to believe. 6) The version of Arial Unicode MS I have doesn't have ñ, despite it being listed as one of the 50k characters by http://www.fileinfo.info. Anything else I could have left out? Thanks for any help!

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  • Is there a good tutorial for figuring out what a website is doing so your program can do the same th

    - by brian d foy
    Is there a good guide or tutorial for people who need to programmatically interact with dynamic websites? There's been a rash of Perl questions about that lately, and I haven't found a good resource to point people toward. I'm asking not because I need one but because I don't want to waste my time writing it if it already exists. Although I'm most interested in Perl, the extra tools and techniques are mostly the same. Typically, I see see these problems in people's questions: Handling, setting, and saving cookies Finding and interacting with forms Handling JavaScript inside your user-agent especially things like onLoad, onSumbit, and Ajax Using HTTP sniffer tools Using Web developer plugins in interactive browsers Interacting with DOM, screen scraping, etc. If there's no good tutorial, I'll add it to my list of things to do (unless someone else wants to do it :). Along the way, if you don't have a suggestion for an existing tutorial, please suggest the things that you think should be in a new one, including links, your favorite tools, and your own user-agent development experiences. I don't care about the particular language you use.

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  • Porting Oracle Procedure to PostgreSQL

    - by Grasper
    I am porting an Oracle function into Postgres PGPLSQL.. I have been using this guide: http://www.postgresql.org/docs/8.1/static/plpgsql.html CREATE OR REPLACE PROCEDURE DATA_UPDATE (mission NUMBER, task NUMBER) AS BEGIN IF mission IS NOT NULL THEN UPDATE MISSION_OBJECTIVE MO SET (MO.MO_TKR_TOTAL_OFF_SCHEDULED, MO.MO_TKR_TOTAL_RECEIVERS) = (SELECT NVL(SUM(RR.TRQ_FUEL_OFFLOAD),0), NVL(SUM(RR.TRQ_NUMBER_RECEIVERS),0) FROM REFUELING_REQUEST RR, MISSION_REQUEST_PAIRING MRP WHERE MO.MSN_INT_ID = MRP.MSN_INT_ID AND MO.MO_INT_ID = MRP.MO_INT_ID AND MRP.REQ_INT_ID = RR.REQ_INT_ID) WHERE MO.MSN_INT_ID = mission AND MO.MO_INT_ID = task ; END IF ; COMMIT ; END ; I've got it this far: CREATE OR REPLACE FUNCTION DATA_UPDATE (NUMERIC, NUMERIC) RETURNS integer as ' DECLARE mission ALIAS for $1; task ALIAS for $2; BEGIN IF mission IS NOT NULL THEN UPDATE MISSION_OBJECTIVE MO SET (MO.MO_TKR_TOTAL_OFF_SCHEDULED, MO.MO_TKR_TOTAL_RECEIVERS) = (SELECT COALESCE(SUM(RR.TRQ_FUEL_OFFLOAD),0), COALESCE(SUM(RR.TRQ_NUMBER_RECEIVERS),0) FROM REFUELING_REQUEST RR, MISSION_REQUEST_PAIRING MRP WHERE MO.MSN_INT_ID = MRP.MSN_INT_ID AND MO.MO_INT_ID = MRP.MO_INT_ID AND MRP.REQ_INT_ID = RR.REQ_INT_ID) WHERE MO.MSN_INT_ID = mission AND MO.MO_INT_ID = task ; END IF; COMMIT; END; ' LANGUAGE plpgsql; This is the error I get: ERROR: syntax error at or near "SELECT" LINE 1: ...OTAL_OFF_SCHEDULED, MO.MO_TKR_TOTAL_RECEIVERS) = (SELECT COA... I do not know why this isn't working... any ideas?

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  • Cross-platform game development: ease of development vs security

    - by alcuadrado
    Hi, I'm a member and contributor of the Argentum Online (AO) community, the first MMORPG from Argentina, which is Free Software; which, although it's not 3D, it's really addictive and has some dozens of thousands of users. Really unluckily AO was developed in Visual Basic (yes, you can laugh) but the former community, so imagine, the code not only sucks, it has zero portability. I'm planning, with some friends to rewrite the client, and as a GNU/Linux frantic, want to do it cross-platform. Some other people is doing the same with the server in Java. So my biggest problem is that we would like to use a rapid development language (like Java, Ruby or Python) but the client would be pretty insecure. Ruby/Python version would have all it's code available, and the Java one would be easily decompilable (yes, we have some crackers in the community) We have consider the option to implement the security module in C/C++ as a dynamic library, but it can be replaced with a custom one, so it's not really secure. We are also considering the option of doing the core application in C++ and the GUI in Ruby/Python. But haven't analysed all it's implications yet. But we really don't want to code the entire game in C/C++ as it doesn't need that much performance (the game is played at 18fps on average) and we want to develop it as fast as possible. So what would you choose in my case? Thank you!

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  • Implementing the ‘defer’ statement from Go in Objective-C?

    - by zoul
    Hello! Today I read about the defer statement in the Go language: A defer statement pushes a function call onto a list. The list of saved calls is executed after the surrounding function returns. Defer is commonly used to simplify functions that perform various clean-up actions. I thought it would be fun to implement something like this in Objective-C. Do you have some idea how to do it? I thought about dispatch finalizers, autoreleased objects and C++ destructors. Autoreleased objects: @interface Defer : NSObject {} + (id) withCode: (dispatch_block_t) block; @end @implementation Defer - (void) dealloc { block(); [super dealloc]; } @end #define defer(__x) [Defer withCode:^{__x}] - (void) function { defer(NSLog(@"Done")); … } Autoreleased objects seem like the only solution that would last at least to the end of the function, as the other solutions would trigger when the current scope ends. On the other hand they could stay in the memory much longer, which would be asking for trouble. Dispatch finalizers were my first thought, because blocks live on the stack and therefore I could easily make something execute when the stack unrolls. But after a peek in the documentation it doesn’t look like I can attach a simple “destructor” function to a block, can I? C++ destructors are about the same thing, I would create a stack-based object with a block to be executed when the destructor runs. This would have the ugly disadvantage of turning the plain .m files into Objective-C++? I don’t really think about using this stuff in production, I’m just interested in various solutions. Can you come up with something working, without obvious disadvantages? Both scope-based and function-based solutions would be interesting.

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  • TLS with SNI in Java clients

    - by ftrotter
    There is an ongoing discussion on the security and trust working group for NHIN Direct regarding the IP-to-domain mapping problem that is created with traditional SSL. If an HISP (as defined by NHIN Direct) wants to host thousands of NHIN Direct "Health Domains" for providers, then it will an "artificially inflated cost" to have to purchase an IP for each of those domains. Because Apache and OpenSSL have recently released TLS with support for the SNI extension, it is possible to use SNI as a solution to this problem on the server side. However, if we decide that we will allow server implementations of the NHINDirect transport layer to support TLS+SNI, then we must require that all clients support SNI too. OpenSSL based clients should do this by default and one could always us stunnel to implement an TLS+SNI aware client to proxy if your given programming language SSL implementation does not support SNI. It appears that native Java applications using OpenJDK do not yet support SNI, but I cannot get a straight answer out of that project. I know that there are OpenSSL Java libraries available but I have no idea if that would be considered viable. Can you give me a "state of the art" summary of where TLS+SNI support is for Java clients? I need a Java implementers perspective on this.

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  • Workflow engine BPMN, Drools, etc or ESB?

    - by Tom
    We currently have an application that is based on an in-house developed workflow engine with YAML based DSL. We are looking to move parts of it to Java. I have discovered a number of java solutions like Intalio, JBPM, Drools Expert, Drools Flow etc. They appear to be aimed at businesses where the business analyst creates the workflows using a graphical editor and submits them to the workflow engine. They seem geared towards ease of use for non-technical people rather than for developers with a focus on human interaction. The workflows tend to look like. Discover-a-file -\ -> join -> process-file -> move-file -> register-file Discover-some-metadata -/ If any step fails we need to retry it X times. We also need to be able to stop the system and be able to restart it and have it continue from where it was (durable). Some of our workflows can be defined by a set of goals we need to achieve so Jess's backwards rule chaining sounds interesting but it is not open source. It might be that what we are after is a Finite State Machine engine or just an Enterprise Service Bus and do everything as JMS queues. Is there a good open source workflow engine that is both standards-based but also geared towards developers. We don't particular want to use a graphical workflow designer or write reams of XML and it should ideally be in Java or language agnostic (makes REST/Soap calls to external services). Thanks, Tom

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  • postgresql error - ERROR: input is out of range

    - by CaffeineIV
    The function below keeps returning this error message. I thought that maybe the double_precision field type was what was causing this, and I tried to use CAST, but either that's not it, or I didn't do it right... Help? Here's the error: ERROR: input is out of range CONTEXT: PL/pgSQL function "calculate_distance" line 7 at RETURN ********** Error ********** ERROR: input is out of range SQL state: 22003 Context: PL/pgSQL function "calculate_distance" line 7 at RETURN And here's the function: CREATE OR REPLACE FUNCTION calculate_distance(character varying, double precision, double precision, double precision, double precision) RETURNS double precision AS $BODY$ DECLARE earth_radius double precision; BEGIN earth_radius := 3959.0; RETURN earth_radius * acos(sin($2 / 57.2958) * sin($4 / 57.2958) + cos($2/ 57.2958) * cos($4 / 57.2958) * cos(($5 / 57.2958) - ($3 / 57.2958))); END; $BODY$ LANGUAGE 'plpgsql' VOLATILE COST 100; ALTER FUNCTION calculate_distance(character varying, double precision, double precision, double precision, double precision) OWNER TO postgres; //I tried changing (unsuccessfully) that RETURN line to: RETURN CAST( (earth_radius * acos(sin($2 / 57.2958) * sin($4 / 57.2958) + cos($2/ 57.2958) * cos($4 / 57.2958) * cos(($5 / 57.2958) - ($3 / 57.2958))) ) AS text);

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  • MacBook Pro - Aquamacs - spell check

    - by peggy Li
    I have tried to use spell check for aquamac. I highlighted a region of the text. Then clicked Edit, then spell check region. I got the error message: Error : No word lists can be found for the language "en_US". Then I went to the website to download the following dictionaries: CocoAspell : I just clicked the download button. It was reported that the download was successful. However, when I tested it and highlighted a text region and clicked spell check. The same error message came out. Do I need to pull the downloaded .pkg to a certain place, such as the application folder, before I opened the .pkg? Or what else do I need to do make it work? I also downloaded the base package Aspell (for Intel) and the pre-built dictionaries as (as the instruction of the website), just the same way as point 1. I still got the same error message. Again, Do I need to pull the downloaded .pkg to a certain place, such as the application folder, before I opened the .pkg? Or what else do I need to do make it work? I would be greatly appreciated if someone could give me some help? Peggy Li

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  • How does one properly redefine self while avoiding the "Multiple methods named ..." warning?

    - by Elise van Looij
    In Apple's The Objective-C Programming Language: Defining a Class the section named "Redifining self" recommends that that class methods allocate and return instances use 'self' only to allocate an instance and then refer only to that instance. Thus, I have a number of subclasses, that have class methods along the lines of: + (id)scrollViewWithFrame: (NSRect)rectFrame { id newInstance = [[[self alloc] initWithFrame:rectFrame] autorelease]; [newInstance setHasHorizontalScroller: YES]; [newInstance setHasVerticalScroller: YES]; [newInstance setBorderType: NSNoBorder]; [newInstance setAutoresizingMask: (NSViewWidthSizable | NSViewHeightSizable)]; return newInstance; } The above is, of course, a subclass of NSScrollView. Unfortunately, Xcode 3.x all these NSView subclasses now raise warnings: "Warning: Multiple methods named '-setAutoresizingMask' found". I believe it has something to do with GCC 4.2, the settings of which I have not changed. The warning is correct, of course, since NSView and its various subclasses all implement setAutoresizingMask, but it is also unnecessary. Since they're only warnings, I ignore them but there is a risk that in between the thirty or so unnecessary ones, a really useful warning lurks which I simply don't see. So, what to do? I do want to adhere to good coding practices and I want to build warning-free apps -- how can I do both?

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  • PostgreSQL: Rolling back a transaction within a plpgsql function?

    - by jamieb
    Coming from the MS SQL world, I tend to make heavy use of stored procedures. I'm currently writing an application uses a lot of PostgreSQL plpgsql functions. What I'd like to do is rollback all INSERTS/UPDATES contained within a particular function if I get an exception at any point within it. I was originally under the impression that each function is wrapped in it's own transaction and that an exception would automatically rollback everything. However, that doesn't seem to be the case. I'm wondering if I ought to be using savepoints in combination with exception handling instead? But I don't really understand the difference between a transaction and a savepoint to know if this is the best approach. Any advice please? CREATE OR REPLACE FUNCTION do_something( _an_input_var int ) RETURNS bool AS $$ DECLARE _a_variable int; BEGIN INSERT INTO tableA (col1, col2, col3) VALUES (0, 1, 2); INSERT INTO tableB (col1, col2, col3); VALUES (0, 1, 'whoops! not an integer'); -- The exception will cause the function to bomb, but the values -- inserted into "tableA" are not rolled back. RETURN True; END; $$ LANGUAGE plpgsql;

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  • Scheme Infix to Postfix

    - by Cody
    Let me establish that this is part of a class assignment, so I'm definitely not looking for a complete code answer. Essentially we need to write a converter in Scheme that takes a list representing a mathematical equation in infix format and then output a list with the equation in postfix format. We've been provided with the algorithm to do so, simple enough. The issue is that there is a restriction against using any of the available imperative language features. I can't figure out how to do this in a purely functional manner. This is our fist introduction to functional programming in my program. I know I'm going to be using recursion to iterate over the list of items in the infix expression like such. (define (itp ifExpr) ( ; do some processing using cond statement (itp (cdr ifExpr)) )) I have all of the processing implemented (at least as best I can without knowing how to do the rest) but the algorithm I'm using to implement this requires that operators be pushed onto a stack and used later. My question is how do I implement a stack in this function that is available to all of the recursive calls as well?

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  • Asymptotic complexity of a compiler

    - by Meinersbur
    What is the maximal acceptable asymptotic runtime of a general-purpose compiler? For clarification: The complexity of compilation process itself, not of the compiled program. Depending on the program size, for instance, the number of source code characters, statements, variables, procedures, basic blocks, intermediate language instructions, assembler instructions, or whatever. This is highly depending on your point of view, so this is a community wiki. See this from the view of someone who writes a compiler. Will the optimisation level -O4 ever be used for larger programs when one of its optimisations takes O(n^6)? Related questions: When is superoptimisation (exponential complexity or even incomputable) acceptable? What is acceptable for JITs? Does it have to be linear? What is the complexity of established compilers? GCC? VC? Intel? Java? C#? Turbo Pascal? LCC? LLVM? (Reference?) If you do not know what asymptotic complexity is: How long are you willing to wait until the compiler compiled your project? (scripting languages excluded)

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  • Is there a way to effect user defined data types in MySQL?

    - by Dancrumb
    I have a database which stores (among other things), the following pieces of information: Hardware IDs BIGINTs Storage Capacities BIGINTs Hardware Names VARCHARs World Wide Port Names VARCHARs I'd like to be able to capture a more refined definition of these datatypes. For instance, the hardware IDs have no numerical significance, so I don't care how they are formatted when displayed. The Storage Capacities, however, are cardinal numbers and, at a user's request, I'd like to present them with thousands and decimal separators, e.g. 123,456.789. Thus, I'd like to refine BIGINT into, say ID_NUMBER and CARDINAL. The same with Hardware Names, which are simple text and WWPNs, which are hexstrings, e.g. 24:68:AC:E0. Thus, I'd like to refine VARCHAR into ENGLISH_WORD and HEXSTRING. The specific datatypes I made up are just for illustrative purposes. I'd like to keep all this information in one place and I'm wondering if anybody knows of a good way to hold this all in my MySQL table definitions. I could use the Comment field of the table definition, but that smells fishy to me. One approach would be to define the data structure elsewhere and use that definition to generate my CREATE TABLEs, but that would be a major rework of the code that I currently have, so I'm looking for alternatives. Any suggestions? The application language in use is Perl, if that helps.

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  • Linux System Programming

    - by AJ
    I wanted to get into systems programming for linux and wanted to know how to approach that and where to begin. I come from a web development background (Python, PHP) but I also know some C and C++. Essentially, I would like to know: Which language(s) to learn and pursue (I think mainly C and C++)? How/Where to learn those languages specific to Systems Programming? Books, websites, blogs, tutorials etc. Any other good places where I can start this from basics? Any good libraries to begin with? What environment setup (or approx.) do I need? Assuming linux has to be there but I have a linux box which I rarely log into using GUI (always use SSH). Is GUI a lot more helpful or VI editor is enough? (Please let me know if this part of the question should go to serverfault.com) PS: Just to clarify, by systems programming I mean things like writing device drivers, System tools, write native applications which are not present on Linux platform but are on others, play with linux kernel etc.

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  • html to text with domdocument class

    - by turbod
    How to get a html page source code without htl tags? For example: <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <meta http-equiv="content-language" content="hu"/> <title>this is the page title</title> <meta name="description" content="this is the description" /> <meta name="keywords" content="k1, k2, k3, k4" /> start the body content <!-- <div>this is comment</div> --> <a href="open.php" title="this is title attribute">open</a> End now one noframes tag. <noframes><span>text</span></noframes> <select name="select" id="select"><option>ttttt</option></select> <div class="robots-nocontent"><span>something</span></div> <img src="url.png" alt="this is alt attribute" /> I need this result: this is the page title this is the description k1, k2, k3, k4 start the body content this is title attribute open End now one noframes tag. text ttttt something this is alt attribute I need too the title and the alt attributes. Idea?

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