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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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• Segmentation in Linux : Segmentation & Paging are redundant?

  - by claws

  Hello, I'm reading "Understanding Linux Kernel". This is the snippet that explains how Linux uses Segmentation which I didn't understand. Segmentation has been included in 80 x 86 microprocessors to encourage programmers to split their applications into logically related entities, such as subroutines or global and local data areas. However, Linux uses segmentation in a very limited way. In fact, segmentation and paging are somewhat redundant, because both can be used to separate the physical address spaces of processes: segmentation can assign a different linear address space to each process, while paging can map the same linear address space into different physical address spaces. Linux prefers paging to segmentation for the following reasons: Memory management is simpler when all processes use the same segment register values that is, when they share the same set of linear addresses. One of the design objectives of Linux is portability to a wide range of architectures; RISC architectures in particular have limited support for segmentation. All Linux processes running in User Mode use the same pair of segments to address instructions and data. These segments are called user code segment and user data segment , respectively. Similarly, all Linux processes running in Kernel Mode use the same pair of segments to address instructions and data: they are called kernel code segment and kernel data segment , respectively. Table 2-3 shows the values of the Segment Descriptor fields for these four crucial segments. I'm unable to understand 1st and last paragraph.

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• A graph-based tuple merge?

  - by user1644030

  I have paired values in tuples that are related matches (and technically still in CSV files). Neither of the paired values are necessarily unique. tupleAB = (A####, B###), (A###, B###), (A###, B###)... tupleBC = (B####, C###), (B###, C###), (B###, C###)... tupleAC = (A####, C###), (A###, C###), (A###, C###)... My ideal output would be a dictionary with a unique ID and a list of "reinforced" matches. The way I try to think about it is in a graph-based context. For example, if: tupleAB[x] = (A0001, B0012) tupleBC[y] = (B0012, C0230) tupleAC[z] = (A0001, C0230) This would produce: output = {uniquekey0001, [A0001, B0012, C0230]} Ideally, this would also be able to scale up to more than three tuples (for example, adding a "D" match that would result in an additional three tuples - AD, BD, and CD - and lists of four items long; and so forth). In regards to scaling up to more tuples, I am open to having "graphs" that aren't necessarily fully connected, i.e., every node connected to every other node. My hunch is that I could easily filter based on the list lengths. I am open to any suggestions. I think, with a few cups of coffee, I could work out a brute force solution, but I thought I'd ask the community if anyone was aware of a more elegant solution. Thanks for any feedback.

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• Join two tables with same # of row but sorted for NULL

  - by VISQL

  I need to join two tables with the same number of rows. Each table has 1 column. There is NO CONNECTING COLUMN to reference for a join. I need to join them side by side because each table was sorted separately so that numeric values are at the top in descinding order. The Table Earners has income values from say 200K down to 0. I cannot just select using 2 cases, because then I will have my first row with Incomes above 100K, but the first 20 or so entries in the second row are NULL. I want the second row to also be sorted descending. I looked up using ORDER BY within CASE but there is no such thing. I have tried to read about row_number() but none of the examples seem to match or make sense. drop table #20plus select case when Income >= 20000 AND Income < 100000 then Income end as 'mula' into #20plus from Earners order by mula desc drop table #100plus select case when Income >= 100000 then Income end as 'dinero' into #100plus from Earners order by dinero desc Select A.dinero, B.mula FROM #100plus as A JOIN #20plus as B ON A.????? = B.????? Since both A and B are sorted descending, moving all NULL to the bottom, what can I reference to join the two tables? Previous output using one SELECT statement with 2 CASE statements dinero mula 2.12688e+007 NULL 1.80031e+007 NULL 1.92415e+006 NULL … … NULL 93530.7 NULL 91000 NULL 84500 Desired output using one SELECT statement after creating two temp TABLES dinero mula 2.12688e+007 93530.7 1.80031e+007 91000 1.92415e+006 84500 … 82500 NULL 82000 NULL … NULL NULL This is Microsoft SQL Server 2008. I'm super new to this, so please give an answer as clear and simplified as possible. Thank you.

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• Basic Question on storing variables c# for use in other classes

  - by Calibre2010

  Ok guys I basically have a class which takes in 3 strings through the parameter of one of its method signatures. I've then tried to map these 3 strings to global variables as a way to store them. However, when I try to call these global variables from another class after instantiating this class they display as null values. this is the class which gets the 3 strings through the method setDate, and the mapping.. public class DateLogic { public string year1; public string month1; public string day1; public DateLogic() { } public void setDate(string year, string month, string day) { year1 = year; month1 = month; day1 = day; // getDate(); } public string getDate() { return year1 + " " + month1 + " " + day1; } } After this I try call this class from here public static string TimeLine2(this HtmlHelper helper, string myString2) { DateLogic g = new DateLogic(); string sday = g.day1; string smonth = g.month1; string syr = g.year1; } I've been debugging and the values make it all the way to the global variables but when called from this class here it doesnt show them, just shows null. Is this cause I'm creating a brand new instance, how do i resolve this?

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• How to initialize audio with Vala/SDL

  - by ioev

  I've been trying to figure this out for a few hours now. In order to start up the audio, I need to create an SDL.AudioSpec object and pass it to SDL.Audio.Open. The problem is, AudioSpec is a class with a private constructor, so when I try to create one I get: sdl.vala:18.25-18.43: error: `SDL.AudioSpec' does not have a default constructor AudioSpec audiospec = new SDL.AudioSpec(); ^^^^^^^^^^^^^^^^^^^ And if I try to just assign values to it's member vars like a struct (it's a struct in normal sdl) I get: sdl.vala:20.3-20.25: error: use of possibly unassigned local variable `audiospec' audiospec.freq = 22050; ^^^^^^^^^^^^^^^^^^^^^^^ I found the valac doc here: http://valadoc.org/sdl/SDL.AudioSpec.html But it isn't much help at all. The offending code block looks like this: // setup the audio configuration AudioSpec audiospec; AudioSpec specback; audiospec.freq = 22050; audiospec.format = SDL.AudioFormat.S16LSB; audiospec.channels = 2; audiospec.samples = 512; // try to initialize sound with these values if (SDL.Audio.open(audiospec, specback) < 0) { stdout.printf("ERROR! Check audio settings!\n"); return 1; } Any help would be greatly appreciated!

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• handling large arrays with array_diff

  - by bigmac

  I have been trying to compare two arrays. Using array_intersect presents no problems. When using array_diff and arrays with ~5,000 values, it works. When I get to ~10,000 values, the script dies when I get to array_diff. Turning on error_reporting did not produce anything. I tried creating my own array_diff function: function manual_array_diff($arraya, $arrayb) { foreach ($arraya as $keya => $valuea) { if (in_array($valuea, $arrayb)) { unset($arraya[$keya]); } } return $arraya; } source: http://stackoverflow.com/questions/2479963/how-does-array-diff-work I would expect it to be less efficient that than the official array_diff, but it can handle arrays of ~10,000. Unfortunately, both array_diffs fail when I get to ~15,000. I tried the same code on a different machine and it runs fine, so it's not an issue with the code or PHP. There must be some limit set somewhere on that particular server. Any idea how I can get around that limit or alter it or just find out what it is?

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• Display a ranking grid for game : optimization of left outer join and find a player

  - by Jerome C.

  Hello, I want to do a ranking grid. I have a table with different values indexed by a key: Table SimpleValue : key varchar, value int, playerId int I have a player which have several SimpleValue. Table Player: id int, nickname varchar Now imagine these records: SimpleValue: Key value playerId for 1 1 int 2 1 agi 2 1 lvl 5 1 for 6 2 int 3 2 agi 1 2 lvl 4 2 Player: id nickname 1 Bob 2 John I want to display a rank of these players on various SimpleValue. Something like: nickname for lvl Bob 1 5 John 6 4 For the moment I generate an sql query based on which SimpleValue key you want to display and on which SimpleValue key you want to order players. eg: I want to display 'lvl' and 'for' of each player and order them on the 'lvl' The generated query is: SELECT p.nickname as nickname, v1.value as lvl, v2.value as for FROM Player p LEFT OUTER JOIN SimpleValue v1 ON p.id=v1.playerId and v1.key = 'lvl' LEFT OUTER JOIN SimpleValue v2 ON p.id=v2.playerId and v2.key = 'for' ORDER BY v1.value This query runs perfectly. BUT if I want to display 10 different values, it generates 10 'left outer join'. Is there a way to simplify this query ? I've got a second question: Is there a way to display a portion of this ranking. Imagine I've 1000 players and I want to display TOP 10, I use the LIMIT keyword. Now I want to display the rank of the player Bob which is 326/1000 and I want to display 5 rank player above and below (so from 321 to 331 position). How can I achieve it ? thanks.

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• Why does a simple ApplicationSetting PropertyBinding for a Form does not work in C#?

  - by Mike Rosenblum

  My question involves this simple walkthrough shown in the article Preserve Size and Location of Windows Forms – Part I by Dennis Wallentin. This approach works 100% fine when using VB.NET. When using the same steps in C#, however, the settings within the Settings tab of the application's properties looks correct, and the app.config file looks right, but the values are not saved when you run it. The app.config file winds up looking like this: <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" > <section name="WindowsAppCs.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" /> </sectionGroup> </configSections> <userSettings> <WindowsAppCs.Properties.Settings> <setting name="Location" serializeAs="String"> <value>0, 0</value> </setting> <setting name="Size" serializeAs="String"> <value>284, 262</value> </setting> </WindowsAppCs.Properties.Settings> </userSettings> </configuration> It looks right to me, but the values do not update when running hosted within Visual Studio or when running the compiled EXE. I am sure that something very simple needs to be added or done, but I don't know what. Does anyone have any ideas here? Much thanks in advance...

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• Modifying existing object attributes in Core Data after the fact

  - by glorifiedHacker

  In a previous question, I was looking for an alternative to modifying how "no date" was being stored in the date attribute of my NSManagedObject subclass. Previously, I had assigned nil to that attribute when a user didn't assign a date. In order to address sorting issues when using NSFetchedResultsController, I have decided to assign [NSDate distantFuture] to the date attribute when a user doesn't assign a date. However, given that this app is already in the wild, I need to update the Core Data store such that any existing nil date values are changed to [NSDate distantFuture]. What is the best way to make this change? The first thing that comes to mind is to iterate through all of the objects in the store in an array and change any nil values that are found. This could be limited to a one-time event by checking against a user defaults key that indicates whether this upgrade has been performed. Is there a way that I can do this with Core Data versioning instead? Or another method that doesn't involve me writing throw-away code?

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• How can I pass a const array or a variable array to a function in C?

  - by CSharperWithJava

  I have a simple function Bar that uses a set of values from a data set that is passed in in the form of an Array of data structures. The data can come from two sources: a constant initialized array of default values, or a dynamically updated cache. The calling function determines which data is used and should be passed to Bar. Bar doesn't need to edit any of the data and in fact should never do so. How should I declare Bar's data parameter so that I can provide data from either set? union Foo { long _long; int _int; } static const Foo DEFAULTS[8] = {1,10,100,1000,10000,100000,1000000,10000000}; static Foo Cache[8] = {0}; void Bar(Foo* dataSet, int len);//example function prototype Note, this is C, NOT C++ if that makes a difference; Edit Oh, one more thing. When I use the example prototype I get a type qualifier mismatch warning, (because I'm passing a mutable reference to a const array?). What do I have to change for that?

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• Stored procedure woes ... inserting binary ...

  - by Wardy

  Ok so I have this storedproc in my SQL 2008 database (works in 2005 too / used to) ... CREATE PROCEDURE [dbo].[SetBinaryContent] @Ref nvarchar(50), @Content varbinary(MAX), @ObjectID uniqueidentifier AS BEGIN DELETE ObjectContent WHERE ObjectId = @ObjectID AND Ref = @Ref IF DATALENGTH(@Content) > 5 BEGIN INSERT INTO ObjectContent (Ref,BinaryContent,ObjectId) VALUES (@Ref,@Content,@ObjectId) END UPDATE Objects SET [Status] = 1 WHERE ID = @ObjectID END Relatively simple, I take a byte array in C# and chuck it in @Content i then give it a guid and string for the other params and off we go. ... Great, it used to work ... but it don't anymore ... so erm ... What's wrong with this stored proc? I've stepped through my C# code thinking I screwed up somehow in that but it definately adds the params and gives them the correct values so what would cause the server to just stop executing this storedproc correctly? When called this proc executes but nothing changes in the db ... no new records are added to the ObjectContent table. Weird huh ...

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• MySQL Normalization stored procedure performance

  - by srkiNZ84

  Hi, I've written a stored procedure in MySQL to take values currently in a table and to "Normalize" them. This means that for each value passed to the stored procedure, it checks whether the value is already in the table. If it is, then it stores the id of that row in a variable. If the value is not in the table, it stores the newly inserted value's id. The stored procedure then takes the id's and inserts them into a table which is equivalent to the original de-normailized table, but this table is fully normalized and consists of mainly foreign keys. My problem with this design is that the stored procedure takes approximately 10ms or so to return, which is too long when you're trying to work through some 10million records. My suspicion is that the performance is to do with the way in which I'm doing the inserts. i.e. INSERT INTO TableA (first_value) VALUES (argument_from_sp) ON DUPLICATE KEY UPDATE id=LAST_INSERT_ID(id); SET @TableAId = LAST_INSERT_ID(); The "ON DUPLICATE KEY UPDATE" is a bit of a hack, due to the fact that on a duplicate key I don't want to update anything but rather just return the id value of the row. If you miss this step though, the LAST_INSERT_ID() function returns the wrong value when you're trying to run the "SET ..." statement. Does anyone know of a better way to do this in MySQL? Thank you

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• Get the key and value of Map that is used Inside another Map (JAVA)

  - by Umair Iqbal

  I am using a map inside another map, The key of the outer map is Integer and the value is another Map. I get the values as expected but I don't know how to get the key and value of teh inner map. Here is the code Map<Integer, Map<Integer, Integer>> cellsMap = new HashMap<Integer, Map<Integer, Integer>>(); Map<Integer , Integer> bandForCell = cellsMap.get(band_number); if (bandForCell == null) bandForCell = new HashMap<Integer, Integer>(); bandForCell.put(erfcn, cell_found); cellsMap.put(band_number, bandForCell); csv.writeCells((Map<Integer, Map<Integer, Integer>>) cellsMap); public void writeCells (Map<Integer, Map<Integer, Integer>> cellsMap ) throws IOException { for (Map.Entry<Integer, Map<Integer, Integer>> entry : cellsMap.entrySet()) { System.out.println("Key: " + entry.getKey() + ". Value: " + entry.getValue() + "\n"); } } Out put of my Map Key: 20 Value: {6331=0, 6330=1, 6329=1, 6328=0, 6335=1, 6437=0, 6436=1} The value in the above output is another map. How can I get the key and value of the inner map from the value of the outer map? Like Keys of inner map = 6331, 6330, 6329 .... and values of inner map = 0 , 1 , 1 , 0 ... Thanks

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• SQL using sum to count results of multiple subqueries

  - by asdas

  I have a table with 2 columns: integer and var char. I am given only the integer values but need to do work on the var char (string) values. Given an integer, and a list of other integers (no overlap), I want to find the string for that single integer. Then I want to take that string and do the INSTR command with that string, and all the other strings for all the other integers. Then I want the sum of all the INSTR so the result is one number. So lets say I have int x, and list y=[y0, y1, y2]. I want to do 3 INSTR commands like SUM(INSTR(string for x, string for y0), INSTR(string for x, string for y1), INSTR(string for x, string for y2)) I think im going in the wrong direction, this is what I have. Im not good with sub queries. SELECT SUM ( SELECT INSTR ( SELECT string FROM pages WHERE int=? LIMIT 1, ( SELECT string FROM pages WHERE id=? OR id=? OR id=? LIMIT 3 ) ) )

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• Call Python From PHP And Get Return Code

  - by seaboy

  Hello everyone, I am calling a python script from PHP. The python program has to return some value according to the arguments passed to it. Here is a sample python program, which will give you a basic idea of what i am doing currently: #!/usr/bin/python import sys #get the arguments passed argList = sys.argv #Not enough arguments. Exit with a value of 1. if len(argList) < 3: #Return with a value of 1. sys.exit(1) arg1 = argList[1] arg2 = argList[2] #Check arguments. Exit with the appropriate value. if len(arg1) > 255: #Exit with a value of 4. sys.exit(4) if len(arg2) < 2: #Exit with a value of 8. sys.exit(8) #Do further coding using the arguments------ #If program works successfully, exit with a value of 0 As you can see from the above code, my basic aim is for the python program to return some values (0,1,4,8 etc) depending on the arguments. And then the calling PHP program to access these returned values and do the appropriate operation. Currently i have used "sys.exit(n)", for that purpose. Am i right in using sys.exit, or do I need to use something else? And also what method exists in PHP so that I can access the return code from python? Sorry for the long question, but hopefully it will help in you understanding my dilemma Thanks a ton

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• DSP - Filter sweep effect

  - by Trap

  I'm implementing a 'filter sweep' effect (I don't know if it's called like that). What I do is basically create a low-pass filter and make it 'move' along a certain frequency range. To calculate the filter cut-off frequency at a given moment I use a user-provided linear function, which yields values between 0 and 1. My first attempt was to directly map the values returned by the linear function to the range of frequencies, as in cf = freqRange * lf(x). Although it worked ok it looked as if the sweep ran much faster when moving through low frequencies and then slowed down during its way to the high frequency zone. I'm not sure why is this but I guess it's something to do with human hearing perceiving changes in frequency in a non-linear manner. My next attempt was to move the filter's cut-off frequency in a logarithmic way. It works much better now but I still feel that the filter doesn't move at a constant perceived speed through the range of frequencies. How should I divide the frequency space to obtain a constant perceived sweep speed? Thanks in advance.

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• mysqldb interfaceError

  - by Johanna

  I have a very weird probleme with mysqldb (mysql module for python). I have a file with queries for inserting records in tables. If I call the functions from the file, it works just fine. But when I try to call one of the functions from another file it throws me a _mysql_exception.InterfaceError: (0, '') I really don't get what I'm doing wrong here.. I call the function from buildDB.py : import create create.newFormat("HD", 0,0,0) The function newFormat(..) is in create.py (imported) : from Database import Database db = Database() def newFormat(name, width=0, height=0, fps=0): format_query = "INSERT INTO Format (form_name, form_width, form_height, form_fps) VALUES ('"+name+"',"+str(width)+","+str(height)+","+str(fps)+");" db.execute(format_query) And the class Databse is the following : import MySQLdb from MySQLdb.constants import FIELD_TYPE class Database(): def __init__(self): server = "localhost" login = "seq" password = "seqmanager" database = "Sequence" my_conv = { FIELD_TYPE.LONG: int } self.conn = MySQLdb.connection(host=server, user=login, passwd=password, db=database, conv=my_conv) # self.cursor = self.conn.cursor() def close(self): self.conn.close() def execute(self, query): self.conn.query(query) (I put only relevant code) Traceback : Z:\sequenceManager\mysql>python buildDB.py D:\ProgramFiles\Python26\lib\site-packages\MySQLdb\__init__.py:34: DeprecationWa rning: the sets module is deprecated from sets import ImmutableSet INSERT INTO Format (form_name, form_width, form_height, form_fps) VALUES ('HD',0 ,0,0); Traceback (most recent call last): File "buildDB.py", line 182, in <module> create.newFormat("HD") File "Z:\sequenceManager\mysql\create.py", line 52, in newFormat db.execute(format_query) File "Z:\sequenceManager\mysql\Database.py", line 19, in execute self.conn.query(query) _mysql_exceptions.InterfaceError: (0, '') The warning has never been a problem before so I don't think it's related.

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• Why is Core Data not persisting these changes to disk?

  - by scott

  I added a new entity to my model and it loads fine but no changes made in memory get persisted to disk. My values set on the car object work fine in memory but aren't getting persisted to disk on hitting the home button (in simulator). I am using almost exactly the same code on another entity in my application and its values persist to disk fine (core data - sqlite3); Does anyone have a clue what I'm overlooking here? Car is the managed object, cars in an NSMutableArray of car objects and Car is the entity and Visible is the attribute on the entity which I am trying to set. Thanks for you assistance. Scott - (void)viewDidLoad { myAppDelegate* appDelegate = (myAppDelegate*)[[UIApplication sharedApplication] delegate]; NSManagedObjectContext* managedObjectContex = appDelegate.managedObjectContext; NSFetchRequest* request = [[NSFetchRequest alloc] init]; NSEntityDescription* entity = [NSEntityDescription entityForName:@"Car" inManagedObjectContext:managedObjectContex]; [request setEntity:entity]; NSSortDescriptor* sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"Name" ascending:YES]; NSArray* sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [request setSortDescriptors:sortDescriptors]; [sortDescriptors release]; [sortDescriptor release]; NSError* error = nil; cars = [[managedObjectContex executeFetchRequest:request error:&error] mutableCopy]; if (cars == nil) { NSLog(@"Can't load the Cars data! Error: %@, %@", error, [error userInfo]); } [request release]; } - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath*)indexPath { Car* car = [cars objectAtIndex:indexPath.row]; if (car.Visible == [NSNumber numberWithBool:YES]) { car.Visible = [NSNumber numberWithBool:NO]; [tableView cellForRowAtIndexPath:indexPath].accessoryType = UITableViewCellAccessoryNone; } else { car.Visible = [NSNumber numberWithBool:YES]; [tableView cellForRowAtIndexPath:indexPath].accessoryType = UITableViewCellAccessoryCheckmark; } }

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• copy rows before updating them to preserve archive in Postgres

  - by punkish

  I am experimenting with creating a table that keeps a version of every row. The idea is to be able to query for how the rows were at any point in time even if the query has JOINs. Consider a system where the primary resource is books, that is, books are queried for, and author info comes along for the ride CREATE TABLE authors ( author_id INTEGER NOT NULL, version INTEGER NOT NULL CHECK (version > 0), author_name TEXT, is_active BOOLEAN DEFAULT '1', modified_on TIMESTAMP DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY (author_id, version) ) INSERT INTO authors (author_id, version, author_name) VALUES (1, 1, 'John'), (2, 1, 'Jack'), (3, 1, 'Ernest'); I would like to be able to update the above like so UPDATE authors SET author_name = 'Jack K' WHERE author_id = 1; and end up with 2, 1, Jack, t, 2012-03-29 21:35:00 2, 2, Jack K, t, 2012-03-29 21:37:40 which I can then query with SELECT author_name, modified_on FROM authors WHERE author_id = 2 AND modified_on < '2012-03-29 21:37:00' ORDER BY version DESC LIMIT 1; to get 2, 1, Jack, t, 2012-03-29 21:35:00 Something like the following doesn't really work CREATE OR REPLACE FUNCTION archive_authors() RETURNS TRIGGER AS $archive_author$ BEGIN IF (TG_OP = 'UPDATE') THEN -- The following fails because author_id,version PK already exists INSERT INTO authors (author_id, version, author_name) VALUES (OLD.author_id, OLD.version, OLD.author_name); UPDATE authors SET version = OLD.version + 1 WHERE author_id = OLD.author_id AND version = OLD.version; RETURN NEW; END IF; RETURN NULL; -- result is ignored since this is an AFTER trigger END; $archive_author$ LANGUAGE plpgsql; CREATE TRIGGER archive_author AFTER UPDATE OR DELETE ON authors FOR EACH ROW EXECUTE PROCEDURE archive_authors(); How can I achieve the above? Or, is there a better way to accomplish this? Ideally, I would prefer to not create a shadow table to store the archived rows.

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• What are the fastest-performing options for a read-only, unordered collection of unique strings?

  - by Dan Tao

  Disclaimer: I realize the totally obvious answer to this question is HashSet<string>. It is absurdly fast, it is unordered, and its values are unique. But I'm just wondering, because HashSet<T> is a mutable class, so it has Add, Remove, etc.; and so I am not sure if the underlying data structure that makes these operations possible makes certain performance sacrifices when it comes to read operations -- in particular, I'm concerned with Contains. Basically, I'm wondering what are the absolute fastest-performing data structures in existence that can supply a Contains method for objects of type string. Within or outside of the .NET framework itself. I'm interested in all kinds of answers, regardless of their limitations. For example I can imagine that some structure might be restricted to strings of a certain length, or may be optimized depending on the problem domain (e.g., range of possible input values), etc. If it exists, I want to hear about it. One last thing: I'm not restricting this to read-only data structures. Obviously any read-write data structure could be embedded inside a read-only wrapper. The only reason I even mentioned the word "read-only" is that I don't have any requirement for a data structure to allow adding, removing, etc. If it has those functions, though, I won't complain.

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• Improving my first Clojure program

  - by StackedCrooked

  After a few weekends exploring Clojure I came up with this program. It allows you to move a little rectangle in a window. Here's the code: (import java.awt.Color) (import java.awt.Dimension) (import java.awt.event.KeyListener) (import javax.swing.JFrame) (import javax.swing.JPanel) (def x (ref 0)) (def y (ref 0)) (def panel (proxy [JPanel KeyListener] [] (getPreferredSize [] (Dimension. 100 100)) (keyPressed [e] (let [keyCode (.getKeyCode e)] (if (== 37 keyCode) (dosync (alter x dec)) (if (== 38 keyCode) (dosync (alter y dec)) (if (== 39 keyCode) (dosync (alter x inc)) (if (== 40 keyCode) (dosync (alter y inc)) (println keyCode))))))) (keyReleased [e]) (keyTyped [e]))) (doto panel (.setFocusable true) (.addKeyListener panel)) (def frame (JFrame. "Test")) (doto frame (.add panel) (.pack) (.setDefaultCloseOperation JFrame/EXIT_ON_CLOSE) (.setVisible true)) (defn drawRectangle [p] (doto (.getGraphics p) (.setColor (java.awt.Color/WHITE)) (.fillRect 0 0 100 100) (.setColor (java.awt.Color/BLUE)) (.fillRect (* 10 (deref x)) (* 10 (deref y)) 10 10))) (loop [] (drawRectangle panel) (Thread/sleep 10) (recur)) Despite being an experienced C++ programmer I found it very challenging to write even a simple application in a language that uses a radically different style than what I'm used to. On top of that, this code probably sucks. I suspect the globalness of the various values is a bad thing. It's also not clear to me if it's appropriate to use references here for the x and y values. Any hints for improving this code are welcome.

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• Why when i rotate the image black borders appear? PHP GD

  - by EAGhost

  This code generates two images using GD and rotates one of them. When I rotate the image black borders begin to appear. Anyone have an idea of how to resolve this? imagefilledrectangle($im, 0, 0, 300, 400, $black); imagefilledrectangle($im, 1, 1, 298, 398, $grey); imagefilledrectangle($im, 49, 69, 251, 271, $black); imagefilledrectangle($im, 50, 70, 250, 270, $white); imagefttext($im, 13, 0, 90, 30, $black, $font_file, "Wind Direcction"); $source=imagecreatetruecolor(100, 100); imagefilledrectangle($source, 0, 0, 100, 100, $white); $values = array( 20, 30, // Point 1 (x, y) 50, 0, 80, 30, 65, 30, 65, 100, 35, 100, 35, 30 // Point 7 (x, y) ); imagefilledpolygon($source, $values, 7, $black1); $asd=imagerotate($source, $rotate, 0); imagecolortransparent($asd, $black); imageantialias($asd, true); $insert_x = imagesx($asd); $insert_y = imagesy($asd); if($rotate==0 || $rotate==90 || $rotate==180 || $rotate==270){ imagecopymerge ( $im , $asd , 100 , 130 , 0 , 0 , $insert_x , $insert_y , 100 ); } if($rotate==45 || $rotate==135 || $rotate==225 || $rotate==315){ imagecopymerge ( $im , $asd , 85 , 110 , 0 , 0 , $insert_x , $insert_y , 100 ); } imageantialias($im, true); header('Content-Type: image/png'); imagepng($im); imagedestroy($im); ?

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• Fixing parent controller's elements after screen orientation

  - by Jonas Anderson

  I have a tab bar application with mixed orientation support for only some views. One of the child view controller shown from one of the tab's navigation controller is displayed only in Landscape mode. In order to accomplish this, I've done the view transformation for the child view as suggested here: Is there a documented way to set the iPhone orientation? The only problem I'm seeing is that after I've performed the orientation adjustment for the child controller and then readjusted orientation back to normal on its dismissal, the contents of the (parent) navigation controller is still shown with Landscape mode dimensions despite the navigation controller reporting the correct value for the interfaceOrientation. How do I ensure that view's size is reset to match the orientation without hardcoding screen dimensions? I have the following in the root navigation controller's viewWillAppear (invoked after the child controller is dismissed): - (void)viewWillAppear:(BOOL)animated { NSLog(@"viewFrame: (%2f, %2f), width: %2f, height: %2f\n", self.view.frame.origin.x, self.view.frame.origin.y, self.view.frame.size.width, self.view.frame.size.height); // Frame values are (0, 0) for (x,y) width: 320, height: 367 before I // displayed child controller. // Frame values are (0,0) width: 480, height: 219 after returning from child // controller -- still has the landscape dimensions NSLog(@"orientation: %d", self.interfaceOrientation); // reports portrait as expected } I've tried to invoke 'layoutIfNeeded' as well as 'setNeedsDisplay' on the view but neither of them bring the view contents into the correct display. Any suggestions would be greatly appreciated.

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• Programming style question on how to code functions

  - by shawnjan

  Hey all! So, I was just coding a bit today, and I realized that I don't have much consistency when it comes to a coding style when programming functions. One of my main concerns is whether or not its proper to code it so that you check that the input of the user is valid OUTSIDE of the function, or just throw the values passed by the user into the function and check if the values are valid in there. Let me sketch an example: I have a function that lists hosts based on an environment, and I want to be able to split the environment into chunks of hosts. So an example of the usage is this: listhosts -e testenv -s 2 1 This will get all the hosts from the "testenv", split it up into two parts, and it is displaying part one. In my code, I have a function that you pass it in a list, and it returns a list of lists based on you parameters for splitting. BUT, before I pass it a list, I first verify the parameters in my MAIN during the getops process, so in the main I check to make sure there are no negatives passed by the user, I make sure the user didnt request to split into say, 4 parts, but asking to display part 5 (which would not be valid), etc. tl;dr: Would you check the validity of a users input the flow of you're MAIN class, or would you do a check in your function itself, and either return a valid response in the case of valid input, or return NULL in the case of invalid input? Obviously both methods work, I'm just interested to hear from experts as to which approach is better :) Thanks for any comments and suggestions you guys have!

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