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• Minimal assembler program for CP/M 3.1 (z80)

  - by Andrew J. Brehm

  I seem to be losing the battle against my stupidity. This site explains the system calls under various versions of CP/M. However, when I try to use call 2 (C_WRITE, console output), nothing much happens. I have the following code. ORG 100h LD E,'a' LD C,2 CALL 5 CALL 0 I recite this here from memory. If there are typos, rest assured they were not in the original since the file did compile and I had a COM file to start. I am thinking the lines mean the following: Make sure this gets loaded at address 100h (0h to FFh being the zero page). Load ASCII 'a' into E register for system call 2. Load integer 2 into C register for system call 2. Make system call (JMP to system call is at address 5 in zero page). End program (Exit command is at address 0 in zero page). The program starts and exits with no problems. If I remove the last command, it hangs the computer (which I guess is also expected and shows that CALL 0 works). However, it does not print the ASCII character. (But it does print an extra new line, but the system might have done that.) How can I get my CP/M program to do what the system call is supposed to do? What am I doing wrong?

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• should the builder reset its build environment after delivering the product

  - by Sudhi

  I am implementing a builder where in the deliverable is retrieved by calling Builder::getProduct() . The director asks various parts to build Builder::buildPartA() , Builder::buildPartB() etc. in order to completely build the product. My question is, once the product is delivered by the Builder by calling Builder::getProduct(), should it reset its environment (Builder::partA = NULL;, Builder::partB = NULL;) so that it is ready to build another product? (with same or different configuration?) I ask this as I am using PHP wherein the objects are by default passed by reference (nope, I don't want to clone them, as one of their field is a Resource) . However, even if you think from a language agnostic point of view, should the Builder reset its build environment ? If your answer is 'it depends on the case' what use cases would justify reseting the environment (and other way round) ? For the sake of providing code sample here's my Builder::gerProcessor() which shows what I mean by reseting the environment /** * @see IBuilder::getProessor() */ public function getProcessor() { if($this->_processor == NULL) { throw new LogicException('Processor not yet built!'); } else { $retval = $this->_processor; $this->_product = NULL, $this->_processor = NULL; } return $retval; }

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• How can I use `pipe` to facilitate interprocess communication in Perl?

  - by Shiftbit

  Can anyone explain how I can successfully get my processes communicating? I find the perldoc on IPC confusing. What I have so far is: $| = 1; $SIG{CHLD} = {wait}; my $parentPid = $$; if ($pid = fork();) ) { if ($pid == 0) { pipe($parentPid, $$); open PARENT, "<$parentPid"; while (<PARENT>) { print $_; } close PARENT; exit(); } else { pipe($parentPid, $pid); open CHILD, ">$pid"; or error("\nError opening: childPid\nRef: $!\n"); open (FH, "<list") or error("\nError opening: list\nRef: $!\n"); while(<FH>) { print CHILD, $_; } close FH or error("\nError closing: list\nRef: $!\n"); close CHILD or error("\nError closing: childPid\nRef: $!\n); } else { error("\nError forking\nRef: $!\n"); } First: What does perldoc pipe mean by READHANDLE, WRITEHANDLE? Second: Can I implement a solution without relying on CPAN or other modules?

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• Understanding Symbols In Ruby

  - by Kezzer

  Despite reading this article, I'm still confused as to the representation of the data in memory when it comes to using symbols. If a symbol, two of them contained in different objects, exist in the same memory location, then how is it that they contain different values? I'd have expected the same memory location to contain the same value. As a quote from the link: Unlike strings, symbols of the same name are initialized and exist in memory only once during a session of ruby I just don't understand how it manages to differentiate the values contained in the same memory location. EDIT So let's consider the example: patient1 = { :ruby => "red" } patient2 = { :ruby => "programming" } patient1.each_key {|key| puts key.object_id.to_s} 3918094 patient2.each_key {|key| puts key.object_id.to_s} 3918094 patient1 and patient2 are both hashes, that's fine. :ruby however is a symbol. If we were to output the following: patient1.each_key {|key| puts key.to_s} Then what will be output? "red", or "programming"? FURTHER EDIT I'm still really quite confused. I'm thinking a symbol is a pointer to a value. Let's forget hashes for a second. The questions I have are; can you assign a value to a symbol? Is a symbol just a pointer to a variable with a value in it? If symbols are global, does that mean a symbol always points to one thing?

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• C Run-Time library part 2

  - by b-gen-jack-o-neill

  Hi, I was suggested when I have some further questions on my older ones, to create newer Question and reffer to old one. So, this is the original question: What is the C runtime library? OK, from your answers, I now get thet statically linked libraries are Microsoft implementation of C standart functions. Now: If I get it right, the scheme would be as follow: I want to use printf(), so I must include which just tels compiler there us functio printf() with these parameters. Now, when I compile code, becouse printf() is defined in C Standart Library, and becouse Microsoft decided to name it C Run Time library, it gets automatically statically linked from libcmt.lib (if libcmt.lib is set in compiler) at compile time. I ask, becouse on wikipedia, in article about runtime library there is that runtime library is linked in runtime, but .lib files are linked at compile time, am I right? Now, what confuses me. There is .dll version of C standart library. But I thought that to link .dll file, you must actually call winapi program to load that library. So, how can be these functions dynamically linked, if there is no static library to provide code to tell Windows to load desired functions from dll? And really last question on this subject - are C Standart library functions also calls to winapi even they are not .dll files like more advanced WinAPI functions? I mean, in the end to access framebuffer and print something you must tell Windows to do it, since OS cannot let you directly manipulate HW. I think of it like the OS must be written to support all C standart library functions same way across similiar versions, since they are statically linked, and can differently support more complex WinAPI calls becouse new version of OS can have adjustements in the .dll file.

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• how to access anti aliasing method of a font with CSS

  - by Daniel Ramirez-Escudero

  I've had this problem in a lot of different webs. You have a font which has different anti-aliasing options, the designer uses the same font with different anti-aliasing options on different parts of the text on the web. So there is a difference between some elements. In this case I have sharp, crisp, strong and smooth. I've used a font generator to get the code to access it via @font-face. Even so, I also have the original .otf if important to know. Is there a method to access this? I upload a picture of what I mean and my actual code: ![@font-face { font-family: 'light'; src: url('../_fnt/light/gothamrnd-light.eot'); src: url('../_fnt/light/gothamrnd-light.eot?#iefix') format('embedded-opentype'), url('../_fnt/light/gothamrnd-light.woff') format('woff'), url('../_fnt/light/gothamrnd-light.ttf') format('truetype'), url('../_fnt/light/gothamrnd-light.svg#../_fnt/light/gothamrnd-light') format('svg'); font-weight: normal; font-style: normal; }]![enter image description here][1]

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• How to identify the type of socket data?

  - by Nitesh Panchal

  Hello, May be i am not able to express my doubt properly in this question but still i will try. Basically i created a simple socket based chat program and everything works fine. But i think i have made many patches in it from the design point of view. I have used ObjectInputStream and ObjectOutputStreams in my program. The question i want to ask is how do i identify the different type of data that i send across the network? say if it is simple String type object i directly add to List<String> chatMessages. Now if want to ban certain users i created an another class :- public class User{ private String name; private String id; //getters and setters } This User class means no importance to me till now but i only created it to properly identify the action. Thus if i receive an instanceOf User i can be sure that some user is to be banned. That way i dont have to hardcode strings. I mean first i thought of sending something like "Banned User :" + userName and then i used to check if string startsWith "Banned User :" then i take some action :p. I've created a User class but it means no importance to me in my program. I want to know whether directly sending strings is good way or create a class for every action that is good. If i am not clear please let me know. If i have hundreds of action do i have to create hundreds of classes so i can check via instanceOf? Say now if i plan to create a BUZZ like facility that is available in yahoo messenger. Should i again create an another class named BUZZ? so it can be identified easily?

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• Groovy / Scala / Java under the hood

  - by Jack

  I used Java for like 6-7 years, then some months ago I discovered Groovy and started to save a lot of typing.. then I wondered how certain things worked under the hood (because groovy performance is really poor) and understood that to give you dynamic typing every Groovy object is a MetaClass object that handles all the things that the JVM couldn't handle by itself. Of course this introduces a layer in the middle between what you write and what you execute that slows down everything. Then somedays ago I started getting some infos about Scala. How these two languages compare in their byte code translations? How much things they add to the normal structure that it would be obtained by plain Java code? I mean, Scala is static typed so wrapper of Java classes should be lighter, since many things are checked during compile time but I'm not sure about the real differences of what's going inside. (I'm not talking about the functional aspect of Scala compared to the other ones, that's a different thing) Can someone enlighten me? From WizardOfOdds it seems like that the only way to get less typing and same performance would be to write an intermediate translator that translates something in Java code (letting javac compile it) without alterating how things are executed, just adding synctatic sugar withour caring about other fallbacks of the language itself.

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• [Android]problem when delete contacts,please help me

  - by Enchor

  I have been working with Android contacts. I am able to show them, update but when I want to delete any, it is not deleted completely. In Contacts application is shown as (Unknown) without any data. Here is my example: ArrayList ops = new ArrayList(); ops.add(ContentProviderOperation.newDelete(Data.CONTENT_URI) .withSelection(Data.CONTACT_ID + "=?", new String[]{selectedid}) .build()); getContentResolver().applyBatch(ContactsContract.AUTHORITY, ops); Should I do anything else to delete contact entirely? It seems that these code delete info in table ContactsContract.Data but it does not delete element related in table ContactsContract.Contacts or ContactsContract.RawContacts.how can i do to delete an contact completely? ============================================================================ also, i tried deprecated method. It dose work, but i do not want to do so. Here is the sample code: ContentResolver contentResolver = m_cContent.getContentResolver(); contentResolver.delete(People.CONTENT_URI, People.NAME + "=?", new String[] { SelectedName }); and if i modify this code to ContentResolver contentResolver = m_cContent.getContentResolver(); contentResolver.delete(ContactsContract.Contacts, ContactsContract.Contacts._ID + "=?", new String[] { Selectedid }); It has no effect. Does it mean that one can only delete a contact by name instead of by its id? What on earth can i do to delete contact? Thanks, Enchor

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• Reading a Wordpress function description

  - by Casebash

  I want to be able to understand the standard function description that is provided for Wordpress functions. In particular, could someone explain the following example from here: Usage <?php wp_list_categories( $args ); ?> Default Usage <?php $args = array( 'show_option_all' => , 'orderby' => 'name', 'order' => 'ASC', 'show_last_update' => 0, 'style' => 'list', 'show_count' => 0, 'hide_empty' => 1, 'use_desc_for_title' => 1, 'child_of' => 0, 'feed' => , 'feed_type' => , 'feed_image' => , 'exclude' => , 'exclude_tree' => , 'include' => , 'current_category' => 0, 'hierarchical' => true, 'title_li' => __( 'Categories' ), 'number' => NULL, 'echo' => 1, 'depth' => 0 ); ?> I can guess most of it, but in particular I can't guess: What does blank after the comma mean? Empty string? What is the __? How do I call the function? Keyword like python, positional arguments or do I have to pass an array? Is there anything else about Wordpress function descriptions which isn't covered in this example? Thanks, Chris

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• How to maintain base files for development environment central while allowing people to change their

  - by Ittai

  Hi, what I'd like to do is have files in a central location so that when I add people to my development team they can see the base version of these files but meanwhile have the ability for the rest of the team to work with their own local version. I know I can just put the files in source-control (we use Tortoiese-SVN) and have my team change the local versions but I'd rather not as the exclamation mark signaling the file has been changed and needs to be committed, quite frankly, irritates me greatly. I'll give two examples of what I mean: We use quite a few build.xml files which relate to a single properties files which contains many definitions. Some of them can be different between team-members (mainly temporary working directories) and I'd like a new team-member to have the ability to get the properties file with the base config but change it if they wish. Have the eclipse settings file in the SVN so that when a new team-member joins they can just retrieve the files from the server and have a base system running. If they wish they will be able to change some of these settings. Thanks, Ittai

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• Transitioning from FlexBuilder 3 to FlashBuilder 4 ... there and back again.

  - by Robusto

  It's growing pains time again. Some of our stuff requires FlashBuilder 4 and some still requires FlexBuilder 3. Both are installed OK, and no projects use both IDEs. The trouble is, when I go back to work on a FlexBuilder 3 project it takes freakin' forever to build and I get weird errors like these: This doesn't seem to cause any identifiable problems except to throw up a modal dialog at various points in the build process, forcing user interaction. But I do notice that memory fills up fast in FB3 and generally FB3 starts behaving strangely and ultimately quits once it gets up over 700MB. This is only a temporary bridge situation until we get all projects into FB4, but "temporary" could mean weeks if not months. Does anyone have any advice for how to get through this bridge period? Is there anything I can do to make these two IDEs work and play well together? Failing that, does anyone know what "java.lang.String" is the "reason" for the problem? Does Eclipse have a resource bundle somewhere that is getting corrupted when i go back and forth between the two?

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• Using SHFileOperation: What errors are occuring

  - by Sascha

  Hello I am using the function SHFileOperation() to send a file to the recycling bin. And I am getting 2 errors that I do not know what they mean because with this function the error codes are not GetLastError() values. Now when the function SHFileOperation() fails the return values are 0x57 (decimal 87) & 0x2 (decimal 2). Can you help me discover the definitions of these errors (expecially when you consider with this function, the errors are not part of the GetLastError() codes). Some important information: • I am using Windows 7 (& I know that MSDN says to use IFileOperation instead of SHFileOperation but I want to make my app backwards compatable which is why I am using SHFileOperation). If the error is occuring because I am using SHFileOperation on Windows 7 what solution could I use to make this work on all versions of windows from 2000 & up? • I have debugged extensively & as far as I know my SHFILEOPSTRUCT is correct (correct flags used, .pFrom is a double-null ended string). One thing I know for sure is that my path to the file is correct (leads to a real file & it correctly formatted). • About 2/5 times the SHFileOperation() works, meaning it sends the file to the recycle bin & does not returns an error BOOL result; SHFILEOPSTRUCT fileStruct; fileStruct.hwnd = hwnd; fileStruct.wFunc = FO_DELETE; fileStruct.pFrom = dest.c_str(); fileStruct.fFlags = FOF_FILESONLY; // FOF_ALLOWUNDO fileStruct.fAnyOperationsAborted = result; // Call operation(delete file) int success = SHFileOperation( &fileStruct ); // if delete was successful if ( success != 0 ) { printf( "%s \t %X %d \n", dest.c_str(), success, success ); cout << result << endl; MessageBox( hwnd, "Failed to delete file", "Error", MB_OK|MB_ICONERROR ); return; }

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• 'Bank Switching' Sprites on old NES applications

  - by Jeffrey Kern

  I'm currently writing in C# what could basically be called my own interpretation of the NES hardware for an old-school looking game that I'm developing. I've fired up FCE and have been observing how the NES displayed and rendered graphics. In a nutshell, the NES could hold two bitmaps worth of graphical information, each with the dimensions of 128x128. These are called the PPU tables. One was for BG tiles and the other was for sprites. The data had to be in this memory for it to be drawn on-screen. Now, if a game had more graphical data then these two banks, it could write portions of this new information to these banks -overwriting what was there - at the end of each frame, and use it from the next frame onward. So, in old games how did the programmers 'bank switch'? I mean, within the level design, how did they know which graphic set to load? I've noticed that Mega Man 2 bankswitches when the screen programatically scrolls from one portion of the stage to the next. But how did they store this information in the level - what sprites to copy over into the PPU tables, and where to write them at? Another example would be hitting pause in MM2. BG tiles get over-written during pause, and then get restored when the player unpauses. How did they remember which tiles they replaced and how to restore them? If I was lazy, I could just make one huge static bitmap and just grab values that way. But I'm forcing myself to limit these values to create a more authentic experience. I've read the amazing guide on how M.C. Kids was made, and I'm trying to be barebones about how I program this game. It still just boggles my mind how these programmers accomplisehd what they did with what they had. EDIT: The only solution I can think of would be to hold separate tables that state what tiles should be in the PPU at what time, but I think that would be a huge memory resource that the NES wouldn't be able to handle.

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• First site going live real soon. Last minute questions

  - by user156814

  I am really close to finishing up on a project that I've been working on. I have done websites before, but never on my own and never a site that involved user generated data. I have been reading up on things that should be considered before you go live and I have some questions. 1) Staging... (Deploying updates without affecting users). I'm not really sure what this would entail, since I'm sure that any type of update would affect users in some way. Does this mean some type of temporary downtime for every update? can somebody please explain this and a solution to this as well. 2) Limits... I'm using the Kohana framework and I'm using the Auth module for logging users in. I was wondering if this already has some type of limit (on login attempts) built in, and if not, what would be the best way to implement this. (save attempts in database, cookie, etc.). If this is not whats meant by limits, can somebody elaborate. 3) Caching... Like I said, this is my first site built around user content. Considering that, should I cache it? 4) Back Ups... How often should I backup my (MySQL) database, and how should I back it up (MySQL export?). The site is currently up, yet not finished, if anybody wants to look at it and see if something pops out to you that should be looked at/fixed. Clashing Thoughts. If there is anything else I overlooked, thats not already in the list linked to above, please let me know. Thanks.

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• Concatenate CLOB-rows with PL/SQL

  - by david K

  Hi, I've got a table which has an id and a clob content like: Create Table v_example_l ( nip number, xmlcontent clob ); We insert our data: Insert into V_EXAMPLE_L (NIP,XMLCONTENT) Values (17852,'<section><block><name>delta</name><content>548484646846484</content></block></section>'); Insert into V_EXAMPLE_L (NIP,XMLCONTENT) Values (17852,'<section><block><name>omega</name><content>545648468484</content></block></section>'); Insert into V_EXAMPLE_L (NIP,XMLCONTENT) Values (17852,'<section><block><name>gamma</name><content>54564846qsdqsdqsdqsd8484</content></block></section>'); I'm trying to do a function that concatenates the rows of the clob that gone be the result of a select, i mean without having to give multiple parameter about the name of table or such, i should only give here the column that contain the clobs, and it should handle the rest. CREATE OR REPLACE function assemble_clob(q varchar2) return clob is v_clob clob; tmp_lob clob; hold VARCHAR2(4000); --cursor c2 is select xmlcontent from V_EXAMPLE_L where id=17852 cur sys_refcursor; begin OPEN cur FOR q; LOOP FETCH cur INTO tmp_lob; EXIT WHEN cur%NOTFOUND; --v_clob := v_clob || XMLTYPE.getClobVal(tmp_lob.xmlcontent); v_clob := v_clob || tmp_lob; END LOOP; return (v_clob); --return (dbms_xmlquery.getXml( dbms_xmlquery.set_context("Select 1 from dual")) ) end assemble_clob; The function is broken... (if anybody could give me a help, thanks a lot, and i'm noob in sql so ....). Thanks!

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• Linear regression confidence intervals in SQL

  - by Matt Howells

  I'm using some fairly straight-forward SQL code to calculate the coefficients of regression (intercept and slope) of some (x,y) data points, using least-squares. This gives me a nice best-fit line through the data. However we would like to be able to see the 95% and 5% confidence intervals for the line of best-fit (the curves below). What these mean is that the true line has 95% probability of being below the upper curve and 95% probability of being above the lower curve. How can I calculate these curves? I have already read wikipedia etc. and done some googling but I haven't found understandable mathematical equations to be able to calculate this. Edit: here is the essence of what I have right now. --sample data create table #lr (x real not null, y real not null) insert into #lr values (0,1) insert into #lr values (4,9) insert into #lr values (2,5) insert into #lr values (3,7) declare @slope real declare @intercept real --calculate slope and intercept select @slope = ((count(*) * sum(x*y)) - (sum(x)*sum(y)))/ ((count(*) * sum(Power(x,2)))-Power(Sum(x),2)), @intercept = avg(y) - ((count(*) * sum(x*y)) - (sum(x)*sum(y)))/ ((count(*) * sum(Power(x,2)))-Power(Sum(x),2)) * avg(x) from #lr Thank you in advance.

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• non static method cannot be referenced from a static context.

  - by David

  First some code: import java.util.*; ... class TicTacToe { ... public static void main (String[]arg) { Random Random = new Random() ; toerunner () ; // this leads to a path of methods that eventualy gets us to the rest of the code } ... public void CompTurn (int type, boolean debug) { ... boolean done = true ; int a = 0 ; while (!done) { a = Random.nextInt(10) ; if (debug) { int i = 0 ; while (i<20) { System.out.print (a+", ") ; i++; }} if (possibles[a]==1) done = true ; } this.board[a] = 2 ; } ... } //to close the class Here is the error message: TicTacToe.java:85: non-static method nextInt(int) cannot be referenced from a static context a = Random.nextInt(10) ; ^ What exactly went wrong? What does that error message "non static method cannot be referenced from a static context" mean?

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• Task predecessor/dependencies logic for task management application

  - by Serge

  Hey guys, I'm trying to figure out the logic for creating tasks that have dependencies. In short I'm building a dynamic task management system and each tasks has several options one of them is to have the task start after a predecessor. Users can add/remove/re-order (by drag&drop) tasks so I'm wondering how can I make the predecessors dynamic, here's an example of what I mean Task 1 Task 2 Task 3 - dependent of task 2 Task 4 - dependent of task 2 Tasks get renamed on delete and/or re-order. If task 1 gets deleted then 3 and 4 should become dependent of task 1 (which is the old task 2). I've been banging my head for the past few hours trying to figure out how to do that. I'm using jQuery right now and each task is contained in a div with an incremental id (ie id="task1") that gets renamed whenever a task is removed or re-ordered and I'm using a dynamically populated drop down for selecting a predecessor. What would be the easiest way to get this done?? by the way, I'm not necessarily asking for code, just trying to figure out the best way to tackle this

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• How would you mask data returned in a Dynamic Data for Entities website?

  - by David Stratton

  I'm doing this in Visual Studio 2008, not 2010, in case there is a relevant difference between the two versions of the Dynamic Data websites. How would I mask data in the automatically generated tables in a Dynamic Data for Entities website? The scenario is we have one table where we want to allow users to ENTER sensitive data, but not VIEW sensitive data, so... (In the list below, I'm using "template" to mean "The web page generated automatically based on the schema and action. I'm sure that's the wrong terminology, but the meaning should be clear.) The "Insert" template should have the field's textbox available for the user to type a value in. The "Edit" template should have the field's textbox blanked out (empty string) regardless of what was in the field in the database in the first place, but the user should be able to type in new data and have it save The "View" template should either have the data for this field masked, or non-visible. The auto-generated table showing the list of records should also have this field masked or non-visible. I can do this easily with standard Web Forms, but I'm having a hard time figuring this out in the Dynamic Data site I'm working on. Masking data is such a common task, I have to believe Microsoft thought of this and provided a way to do it...

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• Retrieving license type (linux/windows/windows+sqlserver) for an Amazon EC2 instance via the API?

  - by Geir

  I need to calculate the hourly running costs for my Amazon EC2 instances. This varies even between instances with same hardware configs (instance types) because I use different amazon images (AMIs): some plain windows server and some windows server with sql server (both of them have additional costs compared with plain linux instances) The EC2 Java API has a describeInstances() method which returns Instance objects with metadata such as instance id, instance type (m1.small/large...), state (running,stopped..) public ip, etc. This Instance object also has a .getLicense().getPool() which according to the Java API should return "The license pool from which this license was used (ex: 'windows')." I thought this is were it may also give 'windows+sqlserver' or something to that effect. The getLicense() method does however return null.. I've navigated around the EC2 web console, not being able to find this information, but I'm hoping that it is possible - otherwise it would mean that you cannot identify the true hourly cost of an particular instance unless you know which AMI was used to create it in the first place (plain windows server or windows server with sql server). Anyone? Thanks :) /Geir

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• CSS font-size causing the last line to be too high

  - by tster

  OK, I have a list (<ul>) then inside each <li> element I have an <a...> Here are all the applicable CSS items to the <a> tag .search_area li a { font-size:11px; } sResCntr li { list-style-type:none; } body { font-family:Arial; } Everything looked great, until I put that font-size:11px in there. The problem is that the hyperlinks wrap to multiple lines within the list (which is fine). But when I decrease the font-size, the last line of the hyperlink always has a larger gap between it and the line above it than the other lines. All the other lines look good, but the last line looks like it is 1.5 spaced or something. I have adjusted the line-height property, but always the last line is larger than the rest. If you need a demo to look at to see what I mean, I can arrange it when I get home.

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• Why does Microsoft advise against readonly fields with mutable values?

  - by Weeble

  In the Design Guidelines for Developing Class Libraries, Microsoft say: Do not assign instances of mutable types to read-only fields. The objects created using a mutable type can be modified after they are created. For example, arrays and most collections are mutable types while Int32, Uri, and String are immutable types. For fields that hold a mutable reference type, the read-only modifier prevents the field value from being overwritten but does not protect the mutable type from modification. This simply restates the behaviour of readonly without explaining why it's bad to use readonly. The implication appears to be that many people do not understand what "readonly" does and will wrongly expect readonly fields to be deeply immutable. In effect it advises using "readonly" as code documentation indicating deep immutability - despite the fact that the compiler has no way to enforce this - and disallows its use for its normal function: to ensure that the value of the field doesn't change after the object has been constructed. I feel uneasy with this recommendation to use "readonly" to indicate something other than its normal meaning understood by the compiler. I feel that it encourages people to misunderstand the meaning of "readonly", and furthermore to expect it to mean something that the author of the code might not intend. I feel that it precludes using it in places it could be useful - e.g. to show that some relationship between two mutable objects remains unchanged for the lifetime of one of those objects. The notion of assuming that readers do not understand the meaning of "readonly" also appears to be in contradiction to other advice from Microsoft, such as FxCop's "Do not initialize unnecessarily" rule, which assumes readers of your code to be experts in the language and should know that (for example) bool fields are automatically initialised to false, and stops you from providing the redundancy that shows "yes, this has been consciously set to false; I didn't just forget to initialize it". So, first and foremost, why do Microsoft advise against use of readonly for references to mutable types? I'd also be interested to know: Do you follow this Design Guideline in all your code? What do you expect when you see "readonly" in a piece of code you didn't write?

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• P/Invoke declarations should not be safe-critical

  - by Bobrovsky

  My code imports following native methods: DeleteObject, GetFontData and SelectObject from gdi32.dll GetDC and ReleaseDC from user32.dll I want to run the code in full trust and medium trust environments (I am fine with exceptions being thrown when these imported methods are indirectly used in medium trust environments). When I run Code Analysis on the code I get warnings like: CA5122 P/Invoke declarations should not be safe-critical. P/Invoke method 'GdiFont.DeleteObject(IntPtr)' is marked safe-critical. Since P/Invokes may only be called by critical code, this declaration should either be marked as security critical, or have its annotation removed entirely to avoid being misleading. Could someone explain me (in layman terms) what does this warning really mean? I tried putting these imports in static SafeNativeMethods class as internal static methods but this doesn't make the warnings go away. I didn't try to put them in NativeMethods because after reading this article I am unsure that it's the right way to go because I don't want my code to be completely unusable in medium trust environments (I think this will be the consequence of moving imports to NativeMethods). Honestly, I am pretty much confused about the real meaning of the warning and consequences of different options to suppressing it. Could someone shed some light on all this? EDIT: My code target .NET 2.0 framework. Assembly is marked with [assembly: AllowPartiallyTrustedCallers] Methods are declared like this: [DllImport("gdi32")] internal static extern int DeleteObject(HANDLE hObject);

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• Does ASP.NET need to be configured for Full Trust to implement 'PageHandlerFactory' ?

  - by Kev

  Our hosting platform (running IIS6/ASP.NET 2.0) is configured to run under partial trust. In the machine wide web.config file we set the ASP.NET trust level to Medium (and lock to prevent overrides) and use a modified policy file. When trying to add a custom HttpHandler to handle .aspx requests for a website running in this configuration I get the following security exception: Security Exception Description: The application attempted to perform an operation not allowed by the security policy. To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file. Exception Details: System.Security.SecurityException: Request failed. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [SecurityException: Request failed.] System.Reflection.Assembly._GetType(String name, Boolean throwOnError, Boolean ignoreCase) +0 System.Reflection.Assembly.GetType(String name, Boolean throwOnError, Boolean ignoreCase) +42 System.Web.Compilation.CompilationUtil.GetTypeFromAssemblies(AssemblyCollection assembliesCollection, String typeName, Boolean ignoreCase) +172 System.Web.Compilation.BuildManager.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) +291 System.Web.Configuration.ConfigUtil.GetType(String typeName, String propertyName, ConfigurationElement configElement, XmlNode node, Boolean checkAptcaBit, Boolean ignoreCase) +52 I'm using a class derived from PageHandlerFactory, for example: public class MyPageHandlerFactory : PageHandlerFactory { public override System.Web.IHttpHandler GetHandler(System.Web.HttpContext context, string requestType, string virtualPath, string path) { // CustomPageHandler derives from System.Web.UI.Page return new CustomPageHandler(); } } My web.config httpHandler configuration is as follow: <httpHandlers> <add verb="*" path="*.aspx" type="MyPageHandler.MyPageHandlerFactory" /> </httpHandlers> The documentation for PageHandlerFactory shows that PageHandlerFactory is decorated with the following attributes: [PermissionSetAttribute(SecurityAction.LinkDemand, Unrestricted = true)] [PermissionSetAttribute(SecurityAction.InheritanceDemand, Unrestricted = true)] public class PageHandlerFactory : IHttpHandlerFactory Does this mean that I need to set ASP.NET to run at Full Trust to be able to create my own PageHandlerFactory classes?

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