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  • Save memory in Python. How to iterate over the lines and save them efficiently with a 2million line

    - by skyl
    I have a tab-separated data file with a little over 2 million lines and 19 columns. You can find it, in US.zip: http://download.geonames.org/export/dump/. I started to run the following but with for l in f.readlines(). I understand that just iterating over the file is supposed to be more efficient so I'm posting that below. Still, with this small optimization, I'm using 10% of my memory on the process and have only done about 3% of the records. It looks like, at this pace, it will run out of memory like it did before. Also, the function I have is very slow. Is there anything obvious I can do to speed it up? Would it help to del the objects with each pass of the for loop? def run(): from geonames.models import POI f = file('data/US.txt') for l in f: li = l.split('\t') try: p = POI() p.geonameid = li[0] p.name = li[1] p.asciiname = li[2] p.alternatenames = li[3] p.point = "POINT(%s %s)" % (li[5], li[4]) p.feature_class = li[6] p.feature_code = li[7] p.country_code = li[8] p.ccs2 = li[9] p.admin1_code = li[10] p.admin2_code = li[11] p.admin3_code = li[12] p.admin4_code = li[13] p.population = li[14] p.elevation = li[15] p.gtopo30 = li[16] p.timezone = li[17] p.modification_date = li[18] p.save() except IndexError: pass if __name__ == "__main__": run()

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  • Python __subclasses__() not listing subclasses

    - by Mridang Agarwalla
    I cant seem to list all derived classes using the __subclasses__() method. Here's my directory layout: import.py backends __init__.py --digger __init__.py base.py test.py --plugins plugina_plugin.py From import.py i'm calling test.py. test.py in turn iterates over all the files in the plugins directory and loads all of them. test.py looks like this: import os import sys import re sys.path.append(os.path.join(os.path.abspath(os.path.dirname(os.path.abspath( __file__ ))))) sys.path.append(os.path.join(os.path.abspath(os.path.dirname(os.path.abspath( __file__ ))), 'plugins')) from base import BasePlugin class TestImport: def __init__(self): print 'heeeeello' PLUGIN_DIRECTORY = os.path.join(os.path.abspath(os.path.dirname(os.path.abspath( __file__ ))), 'plugins') for filename in os.listdir (PLUGIN_DIRECTORY): # Ignore subfolders if os.path.isdir (os.path.join(PLUGIN_DIRECTORY, filename)): continue else: if re.match(r".*?_plugin\.py$", filename): print ('Initialising plugin : ' + filename) __import__(re.sub(r".py", r"", filename)) print ('Plugin system initialized') print BasePlugin.__subclasses__() The problem us that the __subclasses__() method doesn't show any derived classes. All plugins in the plugins directory derive from a base class in the base.py file. base.py looks like this: class BasePlugin(object): """ Base """ def __init__(self): pass plugina_plugin.py looks like this: from base import BasePlugin class PluginA(BasePlugin): """ Plugin A """ def __init__(self): pass Could anyone help me out with this? Whatm am i doing wrong? I've racked my brains over this but I cant seem to figure it out Thanks.

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  • WCF service consuming passively issued SAML token

    - by Neillyboy
    What is the best way to pass an existing SAML token from a website already authenticated via a passive STS? We have built an Identity Provider which is issuing passive claims to the website for authentication. We have this working. Now we would like to add some WCF services into the mix - calling them from the context of the already authenticated web application. Ideally we would just like to pass the SAML token on without doing anything to it (i.e. adding new claims / re-signing). All of the examples I have seen require the ActAs sts implementation - but is this really necessary? This seems a bit bloated for what we want to achieve. I would have thought a simple implementation passing the bootstrap token into the channel - using the CreateChannelActingAs or CreateChannelWithIssuedToken mechanism (and setting ChannelFactory.Credentials.SupportInteractive = false) to call the WCF service with the correct binding (what would that be?) would have been enough. We are using the Fabrikam example code as reference, but as I say, think the ActAs functionality here is overkill for what we are trying to achieve.

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  • How to get the equivalent of the accuracy in Google Map Geocoder V3

    - by Scorpi0
    Hi, I want to get geocode from google, and I used to do it with the V2 of the API. Google send in the json a pretty good information, the accuracy, reference here : http://code.google.com/intl/fr-FR/apis/maps/documentation/javascript/v2/reference.html#GGeoAddressAccuracy In V3, Google doesn't seem to send me exactly the same information. There is the array "adresse_component", which seem bigger if the accuracy is better, but not exactly. For example, I have a request accuracy to the street number, the array is of size 8. Another query is accuracy to the route, so less accuracy, but the array is style of size 8, as there is a row 'sublocality', which not appear in the first case. Ok, for a result, Google send a data 'types', which have the 'best' accuracy. This types are here : http://code.google.com/intl/fr-FR/apis/maps/documentation/geocoding/#Types But, there is no real order, and if I wan't the result better than postal_code, I have no clue to how to do that. So, how can I get this equivalent of the V2 accuracy, whithout some dumb and horrible code ?

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  • How do I create a python module from a fortran program with f2py?

    - by Lars Hellemo
    I am trying to read some smps files with python, and found a fortran implementation, so I thought I would give f2py a shot. The problem is that I have no experience with fortran. I have successfully installed gfortran and f2py on my Linux box and ran the example on thew f2py page, but I have some trouble compiling and running the large program. There are two files, one with a file reader wrapper and one with all the logic. They seem to call each other, but when I compile and link or try f2py, I get errors that they somehow can't find each other: f95 -c FILEWR~1.F f95 -c SMPSREAD.F90 f95 -o smpsread SMPSREAD.o FILEWR~1.o FILEWR~1.o In function `file_wrapper_' FILEWR~1.F(.text+0x3d) undefined reference to `chopen_' usrlibgcci486-linux-gnu4.4.1libgfortranbegin.a(fmain.o) In function `main' (.text+0x27) undefined reference to `MAIN__' collect2 ld returned 1 exit status I also tried changing the name to FILE_WRAPPER.F but that did not help. With f2py I found out I had to include a comment to get it to accept free format, and saved this as a new file and tried: f2py -c -m smpsread smpsread.f90 I get a lot of output and warnings, but the error seems to be this one: getctype: No C-type found in "{'typespec': 'type', 'attrspec': ['allocatable'], 'typename': 'node', 'dimension': [':']}", assuming void. The fortran 90 spms reader can be found here. Any help or suggestions appreciated.

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  • Passing a URL as a URL parameter

    - by Andrea
    I am implementing OpenId login in a CakePHP application. At a certain point, I need to redirect to another action, while preserving the information about the OpenId identity, which is itself a URL (with GET parameters), for instance https://www.google.com/accounts/o8/id?id=31g2iy321i3y1idh43q7tyYgdsjhd863Es How do I pass this data? The first attempt would be function openid() { ... $this->redirect(array('controller' => 'users', 'action' => 'openid_create', $openid)); } but the obvious problem is that this completely messes up the way CakePHP parses URL parameters. I'd need to do either of the following: 1) encode the URL in a CakePHP friendly manner for passing it, and decoding it after that, or 2) pass the URL as a POST parameter but I don't know how to do this. EDIT: In response to comments, I should be more clear. I am using the OpenId component, and I have a working OpenId implementation. What I need to do is to link OpenId with an existing user system. When a new user logs in via OpenId, I ask for more details, and then create a new user with this data. The problem is that I have to keep the OpenId URL throughout this process.

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  • Correct use of Classloader (especially in Android)

    - by Sebi
    I read some documentations about classloaders, but im still not sure where and why they are needed. The Android API says: Loads classes and resources from a repository. One or more class loaders are installed at runtime. These are consulted whenever the runtime system needs a specific class that is not yet available in-memory. So if i understand this correct, there can be many classlaoders which are responsible for loading new classes. But how the system decides which to use? And in which situation should a developer instantiate a new classloader? In the Android API for Intent there is a method public void setExtrasClassLoader (ClassLoader loader) The description says: Sets the ClassLoader that will be used when unmarshalling any Parcelable values from the extras of this Intent. So can i define there a special classloader so that i can pass object with an Intent which are not defined in the receiving activity? An example: If activity A which is located in Project A (in Eclipse) defines an object which i want to send to Activity B in Project B using putExtra of the Intent object. If this object which is send over the Intent is not defined (source code in project B), then there is a NoClassDefFoundException. So can i use the method setExtraClassloader to avoid this exception? If yes, how can i decide which classloader object i have to pass? And how do I instantiate it correctly?

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  • Mysqli connection trying with different users

    - by gerardo
    I'm trying to create a PHP class extending mysqli that is capable of connecting with another user if the connection fails. It is probably easier to explain with code: public function __construct() { $users = new ArrayObject(self::$user); $passwords = new ArrayObject(self::$pass); $itUser = $users->getIterator(); $itPass = $passwords->getIterator(); parent::__construct(self::$host, $itUser->current(), $itPass->current(), self::$prefix.self::$db); while($this->connect_errno && $itUser->valid()){ $itUser->next(); $itPass->next(); $this->change_user($itUser->current(), $itPass->current(), self::$prefix.self::$db); } if($this->connect_errno) throw new Exception("Error", $this->connect_errno); } $user and $pass are static variables containing arrays of users and passwords. If the first user fails to connect, I try with the next one. The problem here is with $this->connect_errno. It says it cannot find Mysqli. Is there any solution to this or should I create a Factory class?

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  • Volatile fields in C#

    - by Danny Chen
    From the specification 10.5.3 Volatile fields: The type of a volatile field must be one of the following: A reference-type. The type byte, sbyte, short, ushort, int, uint, char, float, bool, System.IntPtr, or System.UIntPtr. An enum-type having an enum base type of byte, sbyte, short, ushort, int, or uint. First I want to confirm my understanding is correct: I guess the above types can be volatile because they are stored as a 4-bytes unit in memory(for reference types because of its address), which guarantees the read/write operation is atomic. A double/long/etc type can't be volatile because they are not atomic reading/writing since they are more than 4 bytes in memory. Is my understanding correct? And the second, if the first guess is correct, why a user defined struct with only one int field in it(or something similar, 4 bytes is ok) can't be volatile? Theoretically it's atomic right? Or it's not allowed simply because that all user defined structs(which is possibly more than 4 bytes) are not allowed to volatile by design?

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  • Technical choices in unmarshaling hash-consed data

    - by Pascal Cuoq
    There seems to be quite a bit of folklore knowledge floating about in restricted circles about the pitfalls of hash-consing combined with marshaling-unmarshaling of data. I am looking for citable references to these tidbits. For instance, someone once pointed me to library aterm and mentioned that the authors had clearly thought about this and that the representation on disk was bottom-up (children of a node come before the node itself in the data stream). This is indeed the right way to do things when you need to re-share each node (with a possible identical node already in memory). This re-sharing pass needs to be done bottom-up, so the unmarshaling itself might as well be, too, so that it's possible to do everything in a single pass. I am in the process of describing difficulties encountered in our own context, and the solutions we found. I would appreciate any citable reference to the kind of aforementioned folklore knowledge. Some people obviously have encountered the problems before (the aterm library is only one example). But I didn't find anything in writing. Even the little piece of information I have about aterm is hear-say. I am not worried it's not reliable (you can't make this up), but "personal communication" and "look how it's done in the source code" are considered poor form in citations. I have enough references on hash-consing alone. I am only interested in references where it interferes with other aspects of programming, such as marshaling or distribution.

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  • Rapid calls to fread crashes the application

    - by Slynk
    I'm writing a function to load a wave file and, in the process, split the data into 2 separate buffers if it's stereo. The program gets to i = 18 and crashes during the left channel fread pass. (You can ignore the couts, they are just there for debugging.) Maybe I should load the file in one pass and use memmove to fill the buffers? if(params.channels == 2){ params.leftChannelData = new unsigned char[params.dataSize/2]; params.rightChannelData = new unsigned char[params.dataSize/2]; bool isLeft = true; int offset = 0; const int stride = sizeof(BYTE) * (params.bitsPerSample/8); for(int i = 0; i < params.dataSize; i += stride) { std::cout << "i = " << i << " "; if(isLeft){ std::cout << "Before Left Channel, "; fread(params.leftChannelData+offset, sizeof(BYTE), stride, file + i); std::cout << "After Left Channel, "; } else{ std::cout << "Before Right Channel, "; fread(params.rightChannelData+offset, sizeof(BYTE), stride, file + i); std::cout << "After Right Channel, "; offset += stride; std::cout << "After offset incr.\n"; } isLeft != isLeft; } } else { params.leftChannelData = new unsigned char[params.dataSize]; fread(params.leftChannelData, sizeof(BYTE), params.dataSize, file); }

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  • iPhone SDK allow touches to affect multiple views

    - by Parad0x13
    I have a main view that has has two buttons on it that control methods to display the next image and display the previous image. In this case the 'Image' is a class that inherits from UIImageView and has multiple pictures on it that you can interact with, and I call this class a 'Pane'. The pane itself handles all the user interaction itself while the main view controls the display of next and previous panes with the buttons. Here is my dilemma, because the pane fully covers the main view it wont allow for the user to tap the buttons on the main view! So once a pane pops up you cannot change it via the buttons! Is there a way to allow touches through transparent parts of a view, or if not how in the world do I achieve this?! I cannot pass touchesBegan or any of those methods from the pane to the superview because all of the button touch methods are created in the xib file. I cannot insert the pane under the control panel because then you wouldn't be able to interact with the pane. And as far as I know theres no way to pass touch events to every single pane within the paneHoldingArray that belongs to the main view I cannot add the command buttons inside of the pane because I want to be able to replace the command button's image with a thumbprint render of the next/previous pane. I've been stuck on this for a very long time, please somebody help me out with a fix action or a new way to re-engineer the code so that it will work!

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  • Access denied when trying to access my database.

    - by Sergio Tapia
    Here's my code: <html> <head> </head> <body> <?php $user = mysql_real_escape_string($_GET["u"]); $pass = mysql_real_escape_string($_GET["p"]); $query = "SELECT * FROM usario WHERE username = '$user' AND password = '$pass'"; mysql_connect(localhost, "root", ""); @mysql_select_db("multas") or die( "Unable to select database"); $result=mysql_query($query); if(mysql_numrows($result) > 0){ echo 'si'; } ?> </body> </html> And here's the error I get when I try to run it Warning: mysql_real_escape_string() [function.mysql-real-escape-string]: Access denied for user 'ODBC'@'localhost' (using password: NO) in C:\xampp\htdocs\useraccess.php on line 7 Warning: mysql_real_escape_string() [function.mysql-real-escape-string]: A link to the server could not be established in C:\xampp\htdocs\useraccess.php on line 7 Warning: mysql_real_escape_string() [function.mysql-real-escape-string]: Access denied for user 'ODBC'@'localhost' (using password: NO) in C:\xampp\htdocs\useraccess.php on line 8 Warning: mysql_real_escape_string() [function.mysql-real-escape-string]: A link to the server could not be established in C:\xampp\htdocs\useraccess.php on line 8 Warning: mysql_numrows() expects parameter 1 to be resource, boolean given in C:\xampp\htdocs\useraccess.php on line 16

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  • Help with SQL Query

    - by djfrear
    With regards to the following statement: Select * From explorer.booking_record booking_record_ Inner Join explorer.client client_ On booking_record_.labelno = client_.labelno Inner Join explorer.tour_hotel tour_hotel_ On tour_hotel_.tourcode = booking_record_.tourrefcode Inner Join explorer.hotelrecord hotelrecord_ On tour_hotel_.hotelcode = hotelrecord_.hotelref Where booking_record_.bookingdate Not Like '0000-00-00' And booking_record_.tourdeparturedate Not Like '0000-00-00' And hotelrecord_.hotelgroup = "LPL" And Year(booking_record_.tourdeparturedate) Between Year(AddDate(Now(), Interval -5 Year)) And Year(Now()) My MySQL skills are certainly not up to scratch, the actual result set I wish to find is "a customer who has been to 5 or more LPL hotels in the past 5 years". So far I havent got as far as dealing with the count as I'm getting a huge number of results with some 250+ per customer. I assume this is to do with the way I'm joining tables. Schema wise the booking_record table contains a tour reference code, which links to tour_hotel which then contains a hotelcode which links to hotelrecord. This hotelrecord table contains the hotelgroup. The client table is joined to the booking_record via a booking reference and a client may have many bookings. If anyone could suggest a way for me to do this I'd be very grateful and hopefully learn enough to do it myself next time! I've been scratching my head over this one for a few hours now! Customers may have many bookings within booking_record Daniel.

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  • Thread-safe data structure design

    - by Inso Reiges
    Hello, I have to design a data structure that is to be used in a multi-threaded environment. The basic API is simple: insert element, remove element, retrieve element, check that element exists. The structure's implementation uses implicit locking to guarantee the atomicity of a single API call. After i implemented this it became apparent, that what i really need is atomicity across several API calls. For example if a caller needs to check the existence of an element before trying to insert it he can't do that atomically even if each single API call is atomic: if(!data_structure.exists(element)) { data_structure.insert(element); } The example is somewhat awkward, but the basic point is that we can't trust the result of "exists" call anymore after we return from atomic context (the generated assembly clearly shows a minor chance of context switch between the two calls). What i currently have in mind to solve this is exposing the lock through the data structure's public API. This way clients will have to explicitly lock things, but at least they won't have to create their own locks. Is there a better commonly-known solution to these kinds of problems? And as long as we're at it, can you advise some good literature on thread-safe design? EDIT: I have a better example. Suppose that element retrieval returns either a reference or a pointer to the stored element and not it's copy. How can a caller be protected to safely use this pointer\reference after the call returns? If you think that not returning copies is a problem, then think about deep copies, i.e. objects that should also copy another objects they point to internally. Thank you.

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  • Simply doing modelType.ToString() isn't sufficient, How can i use it via Activator.CreateInstance?

    - by programmerist
    public class MyController { public object CreateByEnum(DataModelType modeltype) { string enumText = modeltype.ToString(); // will return for example "Company" Type classType = Type.GetType(enumText); // the Type for Company class object t = Activator.CreateInstance(classType); // create an instance of Company class return t; } } public class CompanyView { public static List<Personel> GetPersonel() { MyController controller = new MyController(); _Company company = controller.CreateByEnum(DataModelType.Company) as _Company; return company.GetPersonel(); } } public enum DataModelType { xyz, klm, tucyz, Company } Yes, I agree Activator.CreateInstance() is very useful. Unfortunately, I need to pass in the correct type. That means building the correct string to pass to Type.GetType(). If I trace through the call to Controller.CreatebyEnum() in the code I posted above, simply doing modelType.ToString() isn't sufficient, even for the case of DataModelType.Company. My solution'll be maintenance bottleneck. What would be better is something that takes the results of modelType.ToString() and then recursively searches through all the types found in all the assemblies loaded in the current AppDomain. According to MSDN, Type.GetType() only searches the current calling assembly, and mscorlib.dll. How can i do that? . i need best performance?

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  • Type or namespace could not be found

    - by Jason Shultz
    I'm using LINQ to SQL to connect my database to my home page. I created my datacontext (named businessModel.dbml) In it I have two tables named Category and Business. In home controller I reference the model and attempt to return to the view the table: var dataContext = new businessModelDataContext(); var business = from b in dataContext.Businesses select b; ViewData["WelcomeMessage"] = "Welcome to Jerome, Arizona!"; ViewData["MottoMessage"] = "Largest Ghost Town in America!"; return View(business); and in the view I have this: <%@ Import Namespace="WelcomeToJerome.Models" %> and <% foreach (business b in (IEnumerable)ViewData.Model) { %> <li><%= b.Title %></li> <% } %> Yet, in the view business is cursed with the red underline and say's that The type or namespace name 'business' could not be found (are you missing a using directive or an assembly reference?) What am I doing wrong? This has had me stumped all afternoon. link to all the code in pastebin: http://pastebin.com/es4RnS2q

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  • usort - more parameters

    - by pgfonline
    Hallo, how can I pass more parameters to usort? I have different functions, which are very similar in structure, I want to have just one function: <?php $arr = array( array('number' => 100, 'string'=>'aaa'), array('number'=>50, 'string'=>'bdef'), array('number'=>150, 'string'=>'cbba') ); usort($arr, 'sortNumberDesc'); //How can I use just a single function? //How can I pass further parameters to usort? function sortNumberDesc($a, $b){ $a = $a['number']; $b = $b['number']; if ($a == $b) return 0; return ($a > $b) ? -1 : +1; } function sortNumberAsc($a, $b){ $a = $a['number']; $b = $b['number']; if ($a == $b) return 0; return ($a < $b) ? -1 : +1; } //I want to do the same with just one function: //Sort ID is the search index, reverse DESC or ASC function sort($a, $b, $sortId='number', $reverse = 0){ $a = $a[$sortId]; $b = $b[$sortId]; if ($a == $b) return 0; if($reverse == false) return ($a > $b) ? -1 : +1; else return ($a < $b) ? -1 : +1; } print_r($arr); ?>

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  • Delete ONE SPECIFIC table of a database - leave the rest intact

    - by Jayomat
    Hi, I have a database where I store two different kinds of data. One table is for favorite routes, the other stores the retrieved routes from a server. I can retrieve the routes etc just fine. But after retrieving the first Route, pressing back or HOME, and then retrieving another route, the routes table is filled with all the old routes plus the new ones. So my question: how do I delete ONLY the routes table and not the whole database because I don't want to delete the added favorites....?! I found the following function in the android docs: public int delete (String table, String whereClause, String[] whereArgs) and I tried to implement it, but I must pass a SQLiteDataBase as an argument. But how? I implemented: public void deleteTableRoutes(SQLiteDataBase db){ db.delete("routes", null, null); } But I want to call this function from a different class where I have no reference to the database.. so what do I have to pass as an argument? Or how do I get a reference to my database? I build my database upon the code example of the NotePadExample from the dev docs. How to solve this problem? thanks

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  • Does anyone have documentation on SHGetSysColor?

    - by Paulo Santos
    I'm trying to find any reference for this function, but I haven't found anything. All I have is an obscure KB from Microsoft referencing that a programmer made boo-boo when coding a part of the Windows Mobile 6 where he should call SHGetSysColor but instead he called GetSysColor that gives a complete different color, for the same spec. From what I could gather the GetSysColor read a color value in the registry from HKEY_LOCAL_MACHINE\Software\Microsoft\Color\SHColor or HKEY_LOCAL_MACHINE\Software\Microsoft\Color\DefSHColor and returns the color according to the index. In that registry I have the following value for a standard Win Mobile 6.5 "DefSHColor"=hex:\ ff,00,00,00,00,00,00,00,dd,dd,dd,00,ff,ff,cc,00,ff,ff,ff,00,15,af,bc,00,15,\ af,bc,00,c9,e7,e9,00,14,9c,a7,00,ff,ff,ff,00,14,9c,a7,00,14,9c,a7,00,14,9c,\ a7,00,15,af,bc,00,14,9c,a7,00,ff,ff,ff,00,c9,e7,e9,00,37,c7,d3,00,37,c7,d3,\ 00,ff,ff,ff,00,00,b7,c9,00,14,9c,a7,00,ff,ff,ff,00,15,af,bc,00,84,84,c3,00,\ 15,af,bc,00,14,9c,a7,00,ff,ff,ff,00,ff,ff,ff,00,00,00,00,00,ff,ff,ff,00,00,\ 00,00,00,ff,ff,ff,00,2e,44,4f,00,00,14,3c,00,00,f0,ff,00,ff,ff,ff,00,c9,e7,\ e9,00,14,9c,a7,00,ff,ff,ff,00,14,9c,a7,00 And I realized that each four bytes represents a different color (RR,GG,BB,AA -- The AA I'm assuming here, as every color there has the AA byte as 00 which would mean that it's a solid color). What I can't get a fix on is what each index mean, as I have 41 different colors in there. Googling for SHGetSysColor in gives me only 7 matches, two of them are the KB from Microsoft (one in English, the other in French) one is from a Russian site (which I don't read), yet another two are from the freepascal.org and one from Koders.com that is describing the commctl.def file. I went to the commctl.h trying to see if I could find reference tom this function, and found absolutely nothing. No search on MSDN, either fro Google, Bing, or the default MSDN search gave me any result. So, does anyone know what indexes are we talking about here?

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  • Question about WeakHashMap

    - by michael
    Hi, In the Javadoc of "http://java.sun.com/j2se/1.4.2/docs/api/java/util/WeakHashMap.html", it said "Each key object in a WeakHashMap is stored indirectly as the referent of a weak reference. Therefore a key will automatically be removed only after the weak references to it, both inside and outside of the map, have been cleared by the garbage collector." And then Note that a value object may refer indirectly to its key via the WeakHashMap itself; that is, a value object may strongly refer to some other key object whose associated value object, in turn, strongly refers to the key of the first value object. But should not both Key and Value should be used weak reference in WeakHashMap? i.e. if there is low on memory, GC will free the memory held by the value object (since the value object most likely take up more memory than key object in most cases)? And if GC free the Value object, the Key Object can be free as well? Basically, I am looking for a HashMap which will reduce memory usage when there is low memory (GC collects the value and key objects if necessary). Is it possible in Java? Thank you.

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  • Are there pitfalls to using static class/event as an application message bus

    - by Doug Clutter
    I have a static generic class that helps me move events around with very little overhead: public static class MessageBus<T> where T : EventArgs { public static event EventHandler<T> MessageReceived; public static void SendMessage(object sender, T message) { if (MessageReceived != null) MessageReceived(sender, message); } } To create a system-wide message bus, I simply need to define an EventArgs class to pass around any arbitrary bits of information: class MyEventArgs : EventArgs { public string Message { get; set; } } Anywhere I'm interested in this event, I just wire up a handler: MessageBus<MyEventArgs>.MessageReceived += (s,e) => DoSomething(); Likewise, triggering the event is just as easy: MessageBus<MyEventArgs>.SendMessage(this, new MyEventArgs() {Message="hi mom"}); Using MessageBus and a custom EventArgs class lets me have an application wide message sink for a specific type of message. This comes in handy when you have several forms that, for example, display customer information and maybe a couple forms that update that information. None of the forms know about each other and none of them need to be wired to a static "super class". I have a couple questions: fxCop complains about using static methods with generics, but this is exactly what I'm after here. I want there to be exactly one MessageBus for each type of message handled. Using a static with a generic saves me from writing all the code that would maintain the list of MessageBus objects. Are the listening objects being kept "alive" via the MessageReceived event? For instance, perhaps I have this code in a Form.Load event: MessageBus<CustomerChangedEventArgs>.MessageReceived += (s,e) => DoReload(); When the Form is Closed, is the Form being retained in memory because MessageReceived has a reference to its DoReload method? Should I be removing the reference when the form closes: MessageBus<CustomerChangedEventArgs>.MessageReceived -= (s,e) => DoReload();

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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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  • Please help with passing multidimensional arrays

    - by nn
    Hi, I'm writing a simple test program to pass multidimensional arrays. I've been struggling to get the signature of the callee function. void p(int (*s)[100], int n) { ... } In the code I have: int s1[10][100], s2[10][1000]; p(s1, 100); This code appears to work, but it's not what I intended. I want to the function p to be oblivious whether the range of values is 100 or 1000, but it should know there are 10 pointers. I tried as a first attempt: void p(int (*s)[10], int n) // n = # elements in the range of the array and also: void p(int **s, int n) // n = # of elements in the range of the array But to no avail can I seem to get this correct. I don't want to hardcode the 100 or 1000, but instead pass it in, but there will always be 10 arrays. Obviously, I want to avoid having to declare the function: void p(int *s1, int *s2, int *s3, ..., int *s10, int n) FYI, I'm looking at the answers to a similar question but still confused.

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  • JQuery UI Tabs - replace tab and contents

    - by Tauren
    What is the best way to replace the currently selected tab and its contents? The content is dynamically generated with jquery, not loaded via a URL. I need to do this from outside of any tab code or tab event handler (show, add, etc.). There is a link elsewhere on the page that should do the following when clicked: Change the tab's title Change the tab's className Clear out all elements of the tabcontent div Change the tabcontent div's className Generate new content inside the tabcontent div Note that the only reference this link's click() handler has is to the JQuery tabs object ($Tabs). I can get the selected tab with $Tabs.tabs('option','selected'). But how can I get a reference to the selected tab's tab and panel? Inside of a jquery tab handler (show, add, etc.), I have access to ui.tab and ui.panel, but is there a way to get them from a tabs option? Would it be better to simply remove the currently selected tab and then add a new tab in the same index location? I'd have to put the code to generate the tab content into the add() handler then I suppose.

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