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  • TransactionScope question - how can I keep the DTC from getting involved in this?

    - by larryq
    (I know the circumstances surrounding the DTC and promoting a transaction can be a bit mysterious to those of us not in the know, but let me show you how my company is doing things, and if you can tell me why the DTC is getting involved, and if possible, what I can do to avoid it, I'd be grateful.) I have code running on an ASP.Net webserver. We have one database, SQL 2008. Our data access code looks something like this-- We have a data access layer that uses a wrapper object for SQLConnections and SQLCommands. Typical use looks like this: void method1() { objDataObject = new DataAccessLayer(); objDataObject.Connection = SomeConnectionMethod(); SqlCommand objCommand = DataAccessUtils.CreateCommand(SomeStoredProc); //create some SqlParameters, add them to the objCommand, etc.... objDataObject.BeginTransaction(IsolationLevel.ReadCommitted); objDataObject.ExecuteNonQuery(objCommand); objDataObject.CommitTransaction(); objDataObject.CloseConnection(); } So indeed, a very thin wrapper around SqlClient, SqlConnection etc. I want to run several stored procs in a transaction, and the wrapper class doesn't allow me access to the SqlTransaction so I can't pass it from one component to the next. This led me to use a TransactionScope: using (TransactionScope tx1 = new TransactionScope(TransactionScope.RequiresNew)) { method1(); method2(); method3(); tx1.Complete(); } When I do this, the DTC gets involved, and unfortunately our webservers don't have "allow remote clients" enabled in the MSDTC settings-- getting IT to allow that will be a fight. I'd love to avoid DTC becoming involved but can I do it? Can I leave out the transactional calls in methods1-3() and just let the TransactionScope figure it all out?

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  • Javascript callback with AJAX + jQuery

    - by Fred
    Hey! I have this jQuery code (function () { function load_page (pagename) { $.ajax({ url: "/backend/index.php/frontend/pull_page/", type: "POST", data: {page: pagename}, success: function (json) { var parsed = $.parseJSON(json); console.log(parsed); return parsed; }, error: function (error) { $('#content').html('Sorry, there was an error: <br>' + error); return false; } }); } ... var json = load_page(page); console.log(json); if (json == false) { $('body').fadeIn(); } else { document.title = json.pagename + ' | The Other Half | freddum.com'; $("#content").html(json.content); $('#header-navigation-ul a:Contains('+page+')').addClass('nav-selected'); $('body').fadeIn(); } })(); and, guessed it, it doesn't work. The AJAX fires fine, the server returns valid JSON but the console.log(json); returns undefined and the js crashes when it gets to json.pagename. The first console.log(parsed) also returns good data so it's just a problem with the return (I think). I knew I was clutching at straws and would be extremely if this worked, but it doesn't. To be honest, I don't know how to program callback functions for this situation. Any help is greatly appreciated!

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  • JPA - Entity design problem

    - by Yatendra Goel
    I am developing a Java Desktop Application and using JPA for persistence. I have a problem mentioned below: I have two entities: Country City Country has the following attribute: CountryName (PK) City has the following attribute: CityName Now as there can be two cities with same name in two different countries, the primaryKey for City table in the datbase is a composite primary key composed of CityName and CountryName. Now my question is How to implement the primary key of the City as an Entity in Java @Entity public class Country implements Serializable { private String countryName; @Id public String getCountryName() { return this.countryName; } } @Entity public class City implements Serializable { private CityPK cityPK; private Country country; @EmbeddedId public CityPK getCityPK() { return this.cityPK; } } @Embeddable public class CityPK implements Serializable { public String cityName; public String countryName; } Now as we know that the relationship from Country to City is OneToMany and to show this relationship in the above code, I have added a country variable in City class. But then we have duplicate data(countryName) stored in two places in the City class: one in the country object and other in the cityPK object. But on the other hand, both are necessary: countryName in cityPK object is necessary because we implement composite primary keys in this way. countryName in country object is necessary because it is the standard way of showing relashionship between objects. How to get around this problem?

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  • Return unordered list from hierarchical sql data

    - by Milan
    I have table with pageId, parentPageId, title columns. Is there a way to return unordered nested list using asp.net, cte, stored procedure, UDF... anything? Table looks like this: PageID ParentId Title 1 null Home 2 null Products 3 null Services 4 2 Category 1 5 2 Category 2 6 5 Subcategory 1 7 5 SubCategory 2 8 6 Third Level Category 1 ... Result should look like this: Home Products Category 1 SubCategory 1 Third Level Category 1 SubCategory 2 Category 2 Services Ideally, list should contain <a> tags as well, but I hope I can add it myself if I find a way to create <ul> list. EDIT 1: I thought that already there is a solution for this, but it seems that there isn't. I wanted to keep it simple as possible and to escape using ASP.NET menu at any cost, because it uses tables by default. Then I have to use CSS Adapters etc. Even if I decide to go down the "ASP.NET menu" route I was able to find only this approach: http://aspalliance.com/822 which uses DataAdapter and DataSet :( Any more modern or efficient way?

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  • How to determine the size of a project (lines of code, function points, other)

    - by sixtyfootersdude
    How would you evaluate project size? Part A: Before you start a project. Part B: For a complete project. I am interested in comparing unrelated projects. Here are some options: 1) Lines of code. I know that this is not a good metric of productivity but is this a reasonable measure of project size? If I wanted to estimate how long it would take to recreate a project would this be a reasonable way to do it? How many lines of code should I estimate a day? 2) Function Points. Functions points are defined as the number of: inputs outputs inquires internal files external interfaces Anyone have a veiw point on whether this is a good measure? Is there a way to **actually do this? Does anyone have another solution? Hours taken seems like it could be a useful metric but not solely. If I ask you what is a "bigger program" and give you two programs how would you approach the question? I have seen several discussions of this on stackover flow but most discuss how to measure programmer productivity. I am more interested in project size.

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  • Is it possible to wrap an asynchronous event and its callback in a function that returns a boolean?

    - by Rob Flaherty
    I'm trying to write a simple test that creates an image element, checks the image attributes, and then returns true/false. The problem is that using the onload event makes the test asynchronous. On it own this isn't a problem (using a callback as I've done in the code below is easy), but what I can't figure out is how to encapsulate this into a single function that returns a boolean. I've tried various combinations of closures, recursion, and self-executing functions but have had no luck. So my question: am I being dense and overlooking something simple, or is this in fact not possible, because, no matter what, I'm still trying to wrap an asynchronous function in synchronous expectations? Here's the code: var supportsImage = function(callback) { var img = new Image(); img.onload = function() { //Check attributes and pass true or false to callback callback(true); }; img.src = 'data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs='; }; supportsImage(function(status){ console.log(status); }); To be clear, what I want is to be able to wrap this in something such that it can be used like: if (supportsImage) { //Do some crazy stuff } Thanks! (Btw, I know there are a ton of SO questions regarding confusion about synchronous vs. asynchronous. Apologies if this can be reduced to something previously answered.)

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  • No "redefinition of default parameter error" for class template member function?

    - by STingRaySC
    Why does the following give no compilation error?: // T.h template<class T> class X { public: void foo(int a = 42); }; // Main.cpp #include "T.h" #include <iostream> template<class T> void X<T>::foo(int a = 13) { std::cout << a << std::endl; } int main() { X<int> x; x.foo(); // prints 42 } It seems as though the 13 is just silently ignored by the compiler. Why is this? The cooky thing is that if the template declaration is in Main.cpp instead of a header file, I do indeed get the default parameter redefinition error. Now I know the compiler will complain about this if it were just an ordinary (non-template) function. What does the standard have to say about default parameters in class template member functions or function templates?

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  • Show users a list of unique items on Java Google App Engine

    - by James
    I've been going round in circles with what must be a very simple challenge but I want to do it the most efficient way from the start. So, I've watched Brett Slatkin's Google IO videos (2008 & 2009) about building scalable apps including http://www.youtube.com/watch?v=AgaL6NGpkB8 and read the docs but as a n00b, I'm still not sure. I'm trying to build an app on GAEJ similar to the original 'hotornot' where a user is presented with an item which they rate. Once they rate it, they are presented with another one which they haven't seen before. My question is this; is it most efficient to do a query up front to grab x items (say 100) and put them in a list (stored in memcache?) or is it better to simply make a query for a new item after each rating. To keep track of the items a user has seen, I'm planning to keep those items' keys in a list property of the user's entity. Does that sound sensible? I've really got myself confused about this so any help would be much appreciated.

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  • Oracle DBMS_PROFILER only shows Anonymous in the results tables

    - by Greg Reynolds
    I am new to DBMS_PROFILER. All the examples I have seen use a simple top-level procedure to demonstrate the use of the profiler, and from there get all the line numbers etc. I deploy all code in packages, and I am having great difficulty getting my profile session to populate the plsql_profiler_units with useful data. Most of my runs look like this: RUNID RUN_COMMENT UNIT_OWNER UNIT_NAME SECS PERCEN ----- ----------- ----------- -------------- ------- ------ 5 Test <anonymous> <anonymous> .00 2.1 Profiler 5 Test <anonymous> <anonymous> .00 2.1 Profiler 5 Test <anonymous> <anonymous> .00 2.1 Profiler I have just embedded the calls to the dbms_profiler.start_profiler, flush_data and stop_profiler as per all the examples. The main difference is that my code is in a package, and calls in to other package. Do you have to profile every single stored procedure in your call stack? If so that makes this tool a little useless! I have checked http://www.dba-oracle.com/t_plsql_dbms_profiler.htm for hints, among other similar sites.

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  • mod_rewrite if file exists

    - by Mathieu Parent
    Hi everyone, I already have two rewrite rules that work correctly for now but some more code has to be added to work perfectly. I have a website hosted at mydomain.com and all subdom.mydomain.com are rewrited to mydomain.com/subs/subdom . My CMS has to handle the request if the file being reached does not exist, the rewrite is done like so: RewriteCond $1 !^subs/ RewriteCond %{HTTP_HOST} ^([^.]+)\.mydomain\.com$ RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^(.*)$ subs/%1/index.php?page=$1 [L] My CMS handles the next part of the parsing as usual. The problem is if a file really exists, I need to link to it without passing through my CMS, I managed to do it like this: RewriteCond $1 !^subs/ RewriteCond %{HTTP_HOST} ^([^.]+)\.mydomain\.com$ RewriteCond %{REQUEST_FILENAME} -f [OR] RewriteCond %{REQUEST_FILENAME} -d RewriteRule ^(.*)$ subs/%1/$1 [L] So far it seems to work like a charm. Now I am being picky and I need to have default files that are stored in subs/default/. If the file exists in the subdomain folder, we should grab this one but if not, we need to get the file from the default subdomain. And if the file does not exist anywhere, we should be using the 404 page from the current subdomain unless there is none. I hope it describes well enough. Thank you for your time!

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  • FF extension: saving a value in preferences and retrieving in the js file

    - by encryptor
    I am making an extension which should take a link as the user input only once. Then the entire extension keeps using that link on various functions in the JS file. When the user changes it, the value accessed by the js file also changes accordingly. I am using the following but it does not work for me var pref_manager = Components.classes["@mozilla.org/preferencesservice;1"].getService(Components.interfaces.nsIPrefService) function setInstance(){ if (pref_manager.prefHasUserValue("myvar")) { instance = pref_manager.getString("myvar"); alert(instance); } if(instance == null){ instance = prompt("Please enter webcenter host and port"); // Setting the value pref_manager.setString("myvar", instance); } } instance is the global variable in which i take the user input. The alert (instance) does not show up, which means there is some problem by the way i am saving the pref or extracting it. Can someone please help me with this. I have never worked with preferences before. so even if there are minor problems i might not be able to figure out.

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  • How do I do MongoDB console-style queries in PHP?

    - by Zoe Boles
    I'm trying to get a MongoDB query from the javascript console into my PHP app. What I'm trying to avoid is having to translate the query into the PHP "native driver"'s format... I don't want to hand build arrays and hand-chain functions any more than I want to manually build an array of MySQL's internal query structure just to get data. I already have a string producing the exact content I want in the Mongo console: db.intake.find({"processed": {"$exists": "false"}}).sort({"insert_date": "1"}).limit(10); The question is, is there a way for me to hand this string, as is, to MongoDB and have it return a cursor with the dataset I request? Right now I'm at the "write your own parser because it's not valid json to kinda turn a subset of valid Mongo queries into the format the PHP native driver wants" state, which isn't very fun. I don't want an ORM or a massive wrapper library; I just want to give a function my query string as it exists in the console and get an Iterator back that I can work with. I know there are a couple of PHP-based Mongo manager applications that apparently take console-style queries and handle them, but initial browsing through their code, I'm not sure how they handle the translation. I absolutely love working with mongo in the console, but I'm rapidly starting to loathe the thought of converting every query into the format the native writer wants...

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  • Flex Modules vs RSL

    - by nil
    Hi, I'm a little bit confused about when is better to use Flex Modules or RSL libriaries (in Flex 3.5). My goal is split my project in several unit projects, so I can test and work separately. Let's assume I have a Customer app and Vendor app. I also have a front-end panel with two buttons. Each button launches Customer app or Vendor app. These applications make different things. They share some .as functions and common components, too. I understand that if I make a main project (for user login and to show a first panel) and two modules (customer, vendor) I must have all that components in my Eclipse project, isn't it? Instead of doing modules, should I create SWC for Vendor and other for Customer app and call from main app by using RSL? So, which option is more suitable? What do you advise me? Which are the trade-offs of each option? On the other side, this flex application is integrated with Java through Blaze and ibatis for persistence managment, and hold by a web apache server. I considered also to create independent war files to keep this indpendence, but I thought this do not optimize flex code. I'm right? Thank you. Nil

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  • .each or search function, how can I make use of those?

    - by Noor
    I have a ul list, with 10 items, and I have a label that displays the selected li text. When I click a button, I need to check the label, versus all the list items to find the matching one, when it finds that I need to assign the corresponding number. I.e. list: Messi Cristiano Zlatan hidden values of list items: www.messi.com www.cronaldo.com www.ibra.com label: Zlatan script (thought)procces: get label text, search list for matching string, get the value of that string. (and if someone could point me in a direction to learn these basic(?) stuff. tried to be as specific as possible, thanks guys! edit: really sorry for not being clear. the li's are all getting a class dynamically (.listitem). the links can be stored in an array or in a hidden field (or other ul thats hidden) it doesn't really matter where the links are.. $('.listitem').click(function() { $("#elname").text($(this).text()); $("#such").attr("href", $(this).attr('value')); }); I was trying that with the li's having values but I realized that li's can't have values.. thanks again!

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  • Designing a class in such a way that it doesn't become a "God object"

    - by devoured elysium
    I'm designing an application that will allow me to draw some functions on a graphic. Each function will be drawn from a set of points that I will pass to this graphic class. There are different kinds of points, all inheriting from a MyPoint class. For some kind of points it will be just printing them on the screen as they are, others can be ignored, others added, so there is some kind of logic associated to them that can get complex. How to actually draw the graphic is not the main issue here. What bothers me is how to make the code logic such that this GraphicMaker class doesn't become the so called God-Object. It would be easy to make something like this: class GraphicMaker { ArrayList<Point> points = new ArrayList<Point>(); public void AddPoint(Point point) { points.add(point); } public void DoDrawing() { foreach (Point point in points) { if (point is PointA) { //some logic here else if (point is PointXYZ) { //...etc } } } } How would you do something like this? I have a feeling the correct way would be to put the drawing logic on each Point object (so each child class from Point would know how to draw itself) but two problems arise: There will be kinds of points that need to know all the other points that exist in the GraphicObject class to know how to draw themselves. I can make a lot of the methods/properties from the Graphic class public, so that all the points have a reference to the Graphic class and can make all their logic as they want, but isn't that a big price to pay for not wanting to have a God class?

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  • How to not use JavaScript with in the elements events attributes but still load via AJAX

    - by thecoshman
    I am currently loading HTMl content via AJAX. I have code for things on different elements onclick attributes (and other event attributes). It does work, but I am starting to find that the code is getting rather large, and hard to read. I have also read that it is considered bad practice to have the event code 'inline' like this and that I should really do by element.onclick = foobar and have foobar defined somewhere else. I understand how with a static page it is fairly easy to do this, just have a script tag at the bottom of the page and once the page is loaded have it executed. This can then attach any and all events as you need them. But how can I get this sort of affect when loading content via AJAX. There is also the slight case that the content loaded can very depending on what is in the database, some times certain sections of HTML, such as tables of results, will not even be displayed there will be something else entirely. I can post some samples of code if any body needs them, but I have no idea what sort of things would help people with this one. I will point out, that I am using Jquery already so if it has some helpful little functions that would be rather sweet¬

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  • Newbie question: When to use extern "C" { //code } ?

    - by Russel
    Hello, Maybe I'm not understanding the differences between C and C++, but when and why do we need to use: extern "C" { ? Apparently its a "linkage convention"? I read about it briefly and noticed that all the .h header files included with MSVS surround their code with it. What type of code exactly is "C code" and NOT "C++ code"? I thought C++ included all C code? I'm guessing that this is not the case and that C++ is different and that standard features/functions exist in one or the other but not both (ie: printf is C and cout is C++), but that C++ is backwards compatible though the extern "C" declaration. Is this correct? My next question depends on the answer to the first, but I'll ask it here anyway: Since MSVS header files that are written in C are surrounded by extern "C" { ... }, when would you ever need to use this yourself in your own code? If your code is C code and you are trying to compile it in a C++ compiler, shouldn't it work without problem because all the standard h files you include will already have the extern "C" thing in them with the C++ compiler? Do you have to use this when compiling in C++ but linking to alteady built C libraries or something? Please help clarify this for me... Thanks! --Keith

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  • How to check whether a CGPoint is inside a UIImageView?

    - by Horace Ho
    In touchesBegan: CGPoint touch_point = [[touches anyObject] locationInView:self.view]; There are tens of UIImageView around, stored in a NSMutableArray images. I'd like to know is there a built-in function to check if a CGPoint (touch_point) is inside one of the images, e.g.: for (UIImageView *image in images) { // how to test if touch_point is tapped on a image? } Thanks Follow up: For unknown reason, pointInside never returns true. Here is the full code. - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; touch_point = [touch locationInView:self.view]; for (UIImageView *image in piece_images) { if ([image pointInside:touch_point withEvent:event]) { image.hidden = YES; } else { image.hidden = NO; } NSLog(@"image %.0f %.0f touch %.0f %.0f", image.center.x, image.center.y, touch_point.x, touch_point.y); } } although I can the two points are sometimes identical in the NSLog output ... I also tried: if ([image pointInside:touch_point withEvent:nil]) the result is the same. never returns a true. To eliminate the chance of anything goes with with the images. I tried the following: if (YES or [image pointInside:touch_point withEvent:event]) all images are hidden ater the first click on screen.

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  • Load SQL query result data into cache in advance

    - by Marc
    I have the following situation: .net 3.5 WinForm client app accessing SQL Server 2008 Some queries returning relatively big amount of data are used quite often by a form Users are using local SQL Express and restarting their machines at least daily Other users are working remotely over slow network connections The problem is that after a restart, the first time users open this form the queries are extremely slow and take more or less 15s on a fast machine to execute. Afterwards the same queries take only 3s. Of course this comes from the fact that no data is cached and must be loaded from disk first. My question: Would it be possible to force the loading of the required data in advance into SQL Server cache? Note My first idea was to execute the queries in a background worker when the application starts, so that when the user starts the form the queries will already be cached and execute fast directly. I however don't want to load the result of the queries over to the client as some users are working remotely or have otherwise slow networks. So I thought just executing the queries from a stored procedure and putting the results into temporary tables so that nothing would be returned. Turned out that some of the result sets are using dynamic columns so I couldn't create the corresponding temp tables and thus this isn't a solution. Do you happen to have any other idea?

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  • Getting element position in IE versus other browsers

    - by Channel72
    We all know IE6 is difficult. But there seems to be disparate behavior in positioning in later versions of IE as well, when compared with Firefox or other browsers. I have a simple pair of javascript functions which finds the position of an element, and then displays another element in relation to the first element. The idea is to get the second element, which is somewhat larger, to appear in front of the first element when the mouse hovers over it. It works fine, except on all versions of Internet Explorer, the position of the second element appears different than in Firefox. The code to get the position of an element is: function getPosition(e) { var left = 0; var top = 0; while (e.offsetParent) { left += e.offsetLeft; top += e.offsetTop; e = e.offsetParent; } left += e.offsetLeft; top += e.offsetTop; return {x:left, y:top}; } And the actual rollover display code is: var pos = getPosition(elem1); elem2.style.top = pos.y - 8; elem2.style.left = pos.x - 6; In Firefox, elem2 appears directly over elem1, as I want it to. But in IE7 or IE8 it appears way off. What is the reason this occurs, and is there a way to fix it?

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  • Setting up relations/mappings for a SQLAlchemy many-to-many database

    - by Brent Ramerth
    I'm new to SQLAlchemy and relational databases, and I'm trying to set up a model for an annotated lexicon. I want to support an arbitrary number of key-value annotations for the words which can be added or removed at runtime. Since there will be a lot of repetition in the names of the keys, I don't want to use this solution directly, although the code is similar. My design has word objects and property objects. The words and properties are stored in separate tables with a property_values table that links the two. Here's the code: from sqlalchemy import Column, Integer, String, Table, create_engine from sqlalchemy import MetaData, ForeignKey from sqlalchemy.orm import relation, mapper, sessionmaker from sqlalchemy.ext.declarative import declarative_base engine = create_engine('sqlite:///test.db', echo=True) meta = MetaData(bind=engine) property_values = Table('property_values', meta, Column('word_id', Integer, ForeignKey('words.id')), Column('property_id', Integer, ForeignKey('properties.id')), Column('value', String(20)) ) words = Table('words', meta, Column('id', Integer, primary_key=True), Column('name', String(20)), Column('freq', Integer) ) properties = Table('properties', meta, Column('id', Integer, primary_key=True), Column('name', String(20), nullable=False, unique=True) ) meta.create_all() class Word(object): def __init__(self, name, freq=1): self.name = name self.freq = freq class Property(object): def __init__(self, name): self.name = name mapper(Property, properties) Now I'd like to be able to do the following: Session = sessionmaker(bind=engine) s = Session() word = Word('foo', 42) word['bar'] = 'yes' # or word.bar = 'yes' ? s.add(word) s.commit() Ideally this should add 1|foo|42 to the words table, add 1|bar to the properties table, and add 1|1|yes to the property_values table. However, I don't have the right mappings and relations in place to make this happen. I get the sense from reading the documentation at http://www.sqlalchemy.org/docs/05/mappers.html#association-pattern that I want to use an association proxy or something of that sort here, but the syntax is unclear to me. I experimented with this: mapper(Word, words, properties={ 'properties': relation(Property, secondary=property_values) }) but this mapper only fills in the foreign key values, and I need to fill in the other value as well. Any assistance would be greatly appreciated.

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  • Cryptography: best practices for keys in memory?

    - by Johan
    Background: I got some data encrypted with AES (ie symmetric crypto) in a database. A server side application, running on a (assumed) secure and isolated Linux box, uses this data. It reads the encrypted data from the DB, and writes back encrypted data, only dealing with the unencrypted data in memory. So, in order to do this, the app is required to have the key stored in memory. The question is, is there any good best practices for this? Securing the key in memory. A few ideas: Keeping it in unswappable memory (for linux: setting SHM_LOCK with shmctl(2)?) Splitting the key over multiple memory locations. Encrypting the key. With what, and how to keep the...key key.. secure? Loading the key from file each time its required (slow and if the evildoer can read our memory, he can probably read our files too) Some scenarios on why the key might leak: evildoer getting hold of mem dump/core dump; bad bounds checking in code leading to information leakage; The first one seems like a good and pretty simple thing to do, but how about the rest? Other ideas? Any standard specifications/best practices? Thanks for any input!

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  • std::list : get next element

    - by sheepsimulator
    I'm trying to build a string using data elements stored in a std::list, where I want commas placed only between the elements (ie, if elements are {A,B,C,D} in list, result string should be "A,B,C,D". This code does not work: typedef std::list< shared_ptr<EventDataItem> > DataItemList; // ... std::string Compose(DataItemList& dilList) { std::stringstream ssDataSegment; for(iterItems = dilList.begin(); iterItems = dilList.end(); iterItems++) { // Lookahead in list to see if next element is end if((iterItems + 1) == dilList.end()) { ssDataSegment << (*iterItems)->ToString(); } else { ssDataSegment << (*iterItems)->ToString() << ","; } } return ssDataSegment.str(); } How do I get at "the-next-item" in a std::list using an iterator? I would expect that it's a linked-list, why can't I get at the next item?

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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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  • Setting the default stack size on Linux globally for the program

    - by wowus
    So I've noticed that the default stack size for threads on linux is 8MB (if I'm wrong, PLEASE correct me), and, incidentally, 1MB on Windows. This is quite bad for my application, as on a 4-core processor that means 64 MB is space is used JUST for threads! The worst part is, I'm never using more than 100kb of stack per thread (I abuse the heap a LOT ;)). My solution right now is to limit the stack size of threads. However, I have no idea how to do this portably. Just for context, I'm using Boost.Thread for my threading needs. I'm okay with a little bit of #ifdef hell, but I'd like to know how to do it easily first. Basically, I want something like this (where windows_* is linked on windows builds, and posix_* is linked under linux builds) // windows_stack_limiter.c int limit_stack_size() { // Windows impl. return 0; } // posix_stack_limiter.c int limit_stack_size() { // Linux impl. return 0; } // stack_limiter.cpp int limit_stack_size(); static volatile int placeholder = limit_stack_size(); How do I flesh out those functions? Or, alternatively, am I just doing this entirely wrong? Remember I have no control over the actual thread creation (no new params to CreateThread on Windows), as I'm using Boost.Thread.

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