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  • Search engine solution for Django that actually works?

    - by prometheus
    The story so far: Decided to go with Xapian as search backend because it has all search-engine features I was looking for, knows about Unicode, stemming, has few dependencies and requires no bloated app-server installation on top of it. Tried Django and Haystack (plus xapian-haystack, the backend glue code to tie Haystack to Xapian) because it was advertised on quite some blogs as "working". Did not work. Neither django-haystack nor the xapian-haystack project provide a version combination that actually works together. MASTER from both projects yields an error from Xapian, so it's not stable at all. Haystack 1.0.1 and xapian-haystack 1.0.x/1.1.0 are not API-compatible. Plus, in a minimally working installation of Haystack 1.0.1 and xapian-haystack MASTER, any complex query yields zero results due to errors in either django-haystack or xapian-haystack (I double-verified this), maybe because the unit-tests actually test very simple cases, and no edge-cases at all. Tried Djapian. The source-code is riddled with spelling errors (mind you, in variable names, not comments), documentation is also riddled with ambiguities and outdated information that will never lead to a working installation. Not surprisingly, users rarely ask for features but how to get it working in the first place. Next on the plate: exploring Solr (installing a Java environment plus Tomcat gives me headaches, the machine is RAM- and CPU-constrained), or Lucene (slightly less headaches, but still). Before I proceed spending more time with a solution that might or might not work as advertised, I'd like to know: Did anyone ever get an actual, real-world search solution working in Django? I'm serious. I find it really frustrating reading about "large problems mostly solved", and then realizing that you will never get a working installation from the source-code because, actually, all bloggers dealing with those "mostly solved problems" never went past basic installation and copy-pasting the official tutorials. So here are the requirements: must be able to search for 10-100 terms in one query must handle + (term must be present) and - (term must not be present), AND/OR must handle arbitrary grouping (i.e. parentheses around AND/OR) must allow for Django-ORM filtering before or after fulltext-search (i.e. pre-/post-processing of results with the full set of filters that Django knows about) alternatively, there must be a facility to bulk-fetch the result set and transform it into a QuerySet should be light on the machine, so preferably no humongous JVM and Java-based app-server installation Is there anything out there that does this? I'm not interested in anecdotal evidence, or references to some blog posts that claim it should be working. I'd like to hear from someone who actually has a fully-functional setup working in the real world, under real conditions, with real queries. EDIT: Let me repeat again that I'm not so much interested in anecdotal evidence that someone, somewhere has a somewhat running installation working with unspecified properties. I already went there, I read all the blog posts, mailing lists, I contacted the authors, but when it came to actual implementation of real-world scenarios, nothing ever worked as advertised. Also, and a user below brought that point up as well, considering the TCO of any project, I'm definitely not interested in hearing that someone, somewhere was able to pull it off once a vendor parachuted in an unknown number of specialists to monkey-patch the whole installation with specific domain-knowledge that's documented nowhere. So, please, if you claim you have a working installation that actually satisfies minimum requirements for a full-fledged search (see requirements above), please provide the following so that we can all benefit from a search solution for Django that actually solves the problem: exact Linux distribution, release version, exact release version of Haystack (or equivalent) and release version of search backend, exact release version of the search engine publicly (!) available documentation how to set up all components exactly in the way that your installation was set up such that the minimal requirements above are met. Thank you.

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  • Implementing a popularity algorithm in Django

    - by TheLizardKing
    I am creating a site similar to reddit and hacker news that has a database of links and votes. I am implementing hacker news' popularity algorithm and things are going pretty swimmingly until it comes to actually gathering up these links and displaying them. The algorithm is simple: Y Combinator's Hacker News: Popularity = (p - 1) / (t + 2)^1.5` Votes divided by age factor. Where` p : votes (points) from users. t : time since submission in hours. p is subtracted by 1 to negate submitter's vote. Age factor is (time since submission in hours plus two) to the power of 1.5.factor is (time since submission in hours plus two) to the power of 1.5. I asked a very similar question over yonder http://stackoverflow.com/questions/1964395/complex-ordering-in-django but instead of contemplating my options I choose one and tried to make it work because that's how I did it with PHP/MySQL but I now know Django does things a lot differently. My models look something (exactly) like this class Link(models.Model): category = models.ForeignKey(Category) user = models.ForeignKey(User) created = models.DateTimeField(auto_now_add = True) modified = models.DateTimeField(auto_now = True) fame = models.PositiveIntegerField(default = 1) title = models.CharField(max_length = 256) url = models.URLField(max_length = 2048) def __unicode__(self): return self.title class Vote(models.Model): link = models.ForeignKey(Link) user = models.ForeignKey(User) created = models.DateTimeField(auto_now_add = True) modified = models.DateTimeField(auto_now = True) karma_delta = models.SmallIntegerField() def __unicode__(self): return str(self.karma_delta) and my view: def index(request): popular_links = Link.objects.select_related().annotate(karma_total = Sum('vote__karma_delta')) return render_to_response('links/index.html', {'links': popular_links}) Now from my previous question, I am trying to implement the algorithm using the sorting function. An answer from that question seems to think I should put the algorithm in the select and sort then. I am going to paginate these results so I don't think I can do the sorting in python without grabbing everything. Any suggestions on how I could efficiently do this? EDIT This isn't working yet but I think it's a step in the right direction: from django.shortcuts import render_to_response from linkett.apps.links.models import * def index(request): popular_links = Link.objects.select_related() popular_links = popular_links.extra( select = { 'karma_total': 'SUM(vote.karma_delta)', 'popularity': '(karma_total - 1) / POW(2, 1.5)', }, order_by = ['-popularity'] ) return render_to_response('links/index.html', {'links': popular_links}) This errors out into: Caught an exception while rendering: column "karma_total" does not exist LINE 1: SELECT ((karma_total - 1) / POW(2, 1.5)) AS "popularity", (S... EDIT 2 Better error? TemplateSyntaxError: Caught an exception while rendering: missing FROM-clause entry for table "vote" LINE 1: SELECT ((vote.karma_total - 1) / POW(2, 1.5)) AS "popularity... My index.html is simply: {% block content %} {% for link in links %} karma-up {{ link.karma_total }} karma-down {{ link.title }} Posted by {{ link.user }} to {{ link.category }} at {{ link.created }} {% empty %} No Links {% endfor %} {% endblock content %} EDIT 3 So very close! Again, all these answers are great but I am concentrating on a particular one because I feel it works best for my situation. from django.db.models import Sum from django.shortcuts import render_to_response from linkett.apps.links.models import * def index(request): popular_links = Link.objects.select_related().extra( select = { 'popularity': '(SUM(links_vote.karma_delta) - 1) / POW(2, 1.5)', }, tables = ['links_link', 'links_vote'], order_by = ['-popularity'], ) return render_to_response('links/test.html', {'links': popular_links}) Running this I am presented with an error hating on my lack of group by values. Specifically: TemplateSyntaxError at / Caught an exception while rendering: column "links_link.id" must appear in the GROUP BY clause or be used in an aggregate function LINE 1: ...karma_delta) - 1) / POW(2, 1.5)) AS "popularity", "links_lin... Not sure why my links_link.id wouldn't be in my group by but I am not sure how to alter my group by, django usually does that.

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  • How to implement an offline reader writer lock

    - by Peter Morris
    Some context for the question All objects in this question are persistent. All requests will be from a Silverlight client talking to an app server via a binary protocol (Hessian) and not WCF. Each user will have a session key (not an ASP.NET session) which will be a string, integer, or GUID (undecided so far). Some objects might take a long time to edit (30 or more minutes) so we have decided to use pessimistic offline locking. Pessimistic because having to reconcile conflicts would be far too annoying for users, offline because the client is not permanently connected to the server. Rather than storing session/object locking information in the object itself I have decided that any aggregate root that may have its instances locked should implement an interface ILockable public interface ILockable { Guid LockID { get; } } This LockID will be the identity of a "Lock" object which holds the information of which session is locking it. Now, if this were simple pessimistic locking I'd be able to achieve this very simply (using an incrementing version number on Lock to identify update conflicts), but what I actually need is ReaderWriter pessimistic offline locking. The reason is that some parts of the application will perform actions that read these complex structures. These include things like Reading a single structure to clone it. Reading multiple structures in order to create a binary file to "publish" the data to an external source. Read locks will be held for a very short period of time, typically less than a second, although in some circumstances they could be held for about 5 seconds at a guess. Write locks will mostly be held for a long time as they are mostly held by humans. There is a high probability of two users trying to edit the same aggregate at the same time, and a high probability of many users needing to temporarily read-lock at the same time too. I'm looking for suggestions as to how I might implement this. One additional point to make is that if I want to place a write lock and there are some read locks, I would like to "queue" the write lock so that no new read locks are placed. If the read locks are removed withing X seconds then the write lock is obtained, if not then the write lock backs off; no new read-locks would be placed while a write lock is queued. So far I have this idea The Lock object will have a version number (int) so I can detect multi-update conflicts, reload, try again. It will have a string[] for read locks A string to hold the session ID that has a write lock A string to hold the queued write lock Possibly a recursion counter to allow the same session to lock multiple times (for both read and write locks), but not sure about this yet. Rules: Can't place a read lock if there is a write lock or queued write lock. Can't place a write lock if there is a write lock or queued write lock. If there are no locks at all then a write lock may be placed. If there are read locks then a write lock will be queued instead of a full write lock placed. (If after X time the read locks are not gone the lock backs off, otherwise it is upgraded). Can't queue a write lock for a session that has a read lock. Can anyone see any problems? Suggest alternatives? Anything? I'd appreciate feedback before deciding on what approach to take.

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  • Two network interfaces and two IP addresses on the same subnet in Linux

    - by Scott Duckworth
    I recently ran into a situation where I needed two IP addresses on the same subnet assigned to one Linux host so that we could run two SSL/TLS sites. My first approach was to use IP aliasing, e.g. using eth0:0, eth0:1, etc, but our network admins have some fairly strict settings in place for security that squashed this idea: They use DHCP snooping and normally don't allow static IP addresses. Static addressing is accomplished by using static DHCP entries, so the same MAC address always gets the same IP assignment. This feature can be disabled per switchport if you ask and you have a reason for it (thankfully I have a good relationship with the network guys and this isn't hard to do). With the DHCP snooping disabled on the switchport, they had to put in a rule on the switch that said MAC address X is allowed to have IP address Y. Unfortunately this had the side effect of also saying that MAC address X is ONLY allowed to have IP address Y. IP aliasing required that MAC address X was assigned two IP addresses, so this didn't work. There may have been a way around these issues on the switch configuration, but in an attempt to preserve good relations with the network admins I tried to find another way. Having two network interfaces seemed like the next logical step. Thankfully this Linux system is a virtual machine, so I was able to easily add a second network interface (without rebooting, I might add - pretty cool). A few keystrokes later I had two network interfaces up and running and both pulled IP addresses from DHCP. But then the problem came in: the network admins could see (on the switch) the ARP entry for both interfaces, but only the first network interface that I brought up would respond to pings or any sort of TCP or UDP traffic. After lots of digging and poking, here's what I came up with. It seems to work, but it also seems to be a lot of work for something that seems like it should be simple. Any alternate ideas out there? Step 1: Enable ARP filtering on all interfaces: # sysctl -w net.ipv4.conf.all.arp_filter=1 # echo "net.ipv4.conf.all.arp_filter = 1" >> /etc/sysctl.conf From the file networking/ip-sysctl.txt in the Linux kernel docs: arp_filter - BOOLEAN 1 - Allows you to have multiple network interfaces on the same subnet, and have the ARPs for each interface be answered based on whether or not the kernel would route a packet from the ARP'd IP out that interface (therefore you must use source based routing for this to work). In other words it allows control of which cards (usually 1) will respond to an arp request. 0 - (default) The kernel can respond to arp requests with addresses from other interfaces. This may seem wrong but it usually makes sense, because it increases the chance of successful communication. IP addresses are owned by the complete host on Linux, not by particular interfaces. Only for more complex setups like load- balancing, does this behaviour cause problems. arp_filter for the interface will be enabled if at least one of conf/{all,interface}/arp_filter is set to TRUE, it will be disabled otherwise Step 2: Implement source-based routing I basically just followed directions from http://lartc.org/howto/lartc.rpdb.multiple-links.html, although that page was written with a different goal in mind (dealing with two ISPs). Assume that the subnet is 10.0.0.0/24, the gateway is 10.0.0.1, the IP address for eth0 is 10.0.0.100, and the IP address for eth1 is 10.0.0.101. Define two new routing tables named eth0 and eth1 in /etc/iproute2/rt_tables: ... top of file omitted ... 1 eth0 2 eth1 Define the routes for these two tables: # ip route add default via 10.0.0.1 table eth0 # ip route add default via 10.0.0.1 table eth1 # ip route add 10.0.0.0/24 dev eth0 src 10.0.0.100 table eth0 # ip route add 10.0.0.0/24 dev eth1 src 10.0.0.101 table eth1 Define the rules for when to use the new routing tables: # ip rule add from 10.0.0.100 table eth0 # ip rule add from 10.0.0.101 table eth1 The main routing table was already taken care of by DHCP (and it's not even clear that its strictly necessary in this case), but it basically equates to this: # ip route add default via 10.0.0.1 dev eth0 # ip route add 130.127.48.0/23 dev eth0 src 10.0.0.100 # ip route add 130.127.48.0/23 dev eth1 src 10.0.0.101 And voila! Everything seems to work just fine. Sending pings to both IP addresses works fine. Sending pings from this system to other systems and forcing the ping to use a specific interface works fine (ping -I eth0 10.0.0.1, ping -I eth1 10.0.0.1). And most importantly, all TCP and UDP traffic to/from either IP address works as expected. So again, my question is: is there a better way to do this? This seems like a lot of work for a seemingly simple problem.

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  • LINQ Generic Query with inherited base class?

    - by sah302
    I am trying to write some generic LINQ queries for my entities, but am having issue doing the more complex things. Right now I am using an EntityDao class that has all my generics and each of my object class Daos (such as Accomplishments Dao) inherit it, am example: using LCFVB.ObjectsNS; using LCFVB.EntityNS; namespace AccomplishmentNS { public class AccomplishmentDao : EntityDao<Accomplishment>{} } Now my entityDao has the following code: using LCFVB.ObjectsNS; using LCFVB.LinqDataContextNS; namespace EntityNS { public abstract class EntityDao<ImplementationType> where ImplementationType : Entity { public ImplementationType getOneByValueOfProperty(string getProperty, object getValue) { ImplementationType entity = null; if (getProperty != null && getValue != null) { //Nhibernate Example: //ImplementationType entity = default(ImplementationType); //entity = Me.session.CreateCriteria(Of ImplementationType)().Add(Expression.Eq(getProperty, getValue)).UniqueResult(Of InterfaceType)() LCFDataContext lcfdatacontext = new LCFDataContext(); //Generic LINQ Query Here lcfdatacontext.GetTable<ImplementationType>(); lcfdatacontext.SubmitChanges(); lcfdatacontext.Dispose(); } return entity; } public bool insertRow(ImplementationType entity) { if (entity != null) { //Nhibernate Example: //Me.session.Save(entity, entity.Id) //Me.session.Flush() LCFDataContext lcfdatacontext = new LCFDataContext(); //Generic LINQ Query Here lcfdatacontext.GetTable<ImplementationType>().InsertOnSubmit(entity); lcfdatacontext.SubmitChanges(); lcfdatacontext.Dispose(); return true; } else { return false; } } } }             I have gotten the insertRow function working, however I am not even sure how to go about doing getOnebyValueOfProperty, the closest thing I could find on this site was: http://stackoverflow.com/questions/2157560/generic-linq-to-sql-query How can I pass in the column name and the value I am checking against generically using my current set-up? It seems like from that link it's impossible since using a where predicate because entity class doesn't know what any of the properties are until I pass them in. Lastly, I need some way of setting a new object as the return type set to the implementation type, in nhibernate (what I am trying to convert from) it was simply this line that did it: ImplentationType entity = default(ImplentationType); However default is an nhibernate command, how would I do this for LINQ? EDIT: getOne doesn't seem to work even when just going off the base class (this is a partial class of the auto generated LINQ classes). I even removed the generics. I tried: namespace ObjectsNS { public partial class Accomplishment { public Accomplishment getOneByWhereClause(Expression<Action<Accomplishment, bool>> singleOrDefaultClause) { Accomplishment entity = new Accomplishment(); if (singleOrDefaultClause != null) { LCFDataContext lcfdatacontext = new LCFDataContext(); //Generic LINQ Query Here entity = lcfdatacontext.Accomplishments.SingleOrDefault(singleOrDefaultClause); lcfdatacontext.Dispose(); } return entity; } } } Get the following error: Error 1 Overload resolution failed because no accessible 'SingleOrDefault' can be called with these arguments: Extension method 'Public Function SingleOrDefault(predicate As System.Linq.Expressions.Expression(Of System.Func(Of Accomplishment, Boolean))) As Accomplishment' defined in 'System.Linq.Queryable': Value of type 'System.Action(Of System.Func(Of LCFVB.ObjectsNS.Accomplishment, Boolean))' cannot be converted to 'System.Linq.Expressions.Expression(Of System.Func(Of LCFVB.ObjectsNS.Accomplishment, Boolean))'. Extension method 'Public Function SingleOrDefault(predicate As System.Func(Of Accomplishment, Boolean)) As Accomplishment' defined in 'System.Linq.Enumerable': Value of type 'System.Action(Of System.Func(Of LCFVB.ObjectsNS.Accomplishment, Boolean))' cannot be converted to 'System.Func(Of LCFVB.ObjectsNS.Accomplishment, Boolean)'. 14 LCF Okay no problem I changed: public Accomplishment getOneByWhereClause(Expression<Action<Accomplishment, bool>> singleOrDefaultClause) to: public Accomplishment getOneByWhereClause(Expression<Func<Accomplishment, bool>> singleOrDefaultClause) Error goes away. Alright, but now when I try to call the method via: Accomplishment accomplishment = new Accomplishment(); var result = accomplishment.getOneByWhereClause(x=>x.Id = 4) It doesn't work it says x is not declared. I also tried getOne, and various other Expression =(

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  • Chaining CSS classes in IE6 - Trying to find a jQuery solution?

    - by Mike Baxter
    Right, perhaps I ask the impossible? I consider myself fairly new to Javscript and jQuery, but that being said, I have written some fairly complex code recently so I am definitely getting there... however I am now possed with a rather interesting issue at my current freelance contract. The previous web coder has taken a Grid-960 approach to the HTML and as a result has used chained classes to style many of the elements. The example below is typical of what can be found in the code: <div class='blocks four-col-1 orange highlight'>Some content</div> And in the css there will be different declarations for: (not actual css... but close enough) .blocks {margin-right:10px;} .orange {background-image:url(someimage.jpg);} .highlight {font-weight:bold;} .four-col-1 {width:300px;} and to make matters worse... this is in the CSS: .blocks.orange.highlight {background-colour:#dd00ff;} Anyone not familiar with this particular bug can read more on it here: http://www.ryanbrill.com/archives/multiple-classes-in-ie/ it is very real and very annoying. Without wanting to go into the merrits of not chaining classes (I told them this, but it is no longer feasible to change their approach... 100 hand coded pages into a 150 page website, no CMS... sigh) and without the luxury of being able to change the way these blocks are styled... can anyone advise me on the complexity and benefits between any of my below proposed approaches or possible other options that would adequately solve this problem. Potential Solution 1 Using conditional comments I am considering loading a jquery script only for IE6 that: Reads the class of all divs in a certain section of the page and pushes to an array creates empty boxes off screen with only one of the classes applied at a time Reads the applied CSS values for each box Re-applies these styles to the individual box, somehow bearing in mind the order in which they are called and overwriting conflicting instructions as required Potential Solution 2 read the class of all divs in a certain section of the page and push to an array Scan the document for links to style sheets Ajax grab the stylesheets and traverse looking for matching names to those in class array Apply styles as needed Potential Solution 3 Create an IE6 only stylesheet containing the exact style to be applied as a unique name (ie: class='blocks orange highlight' becomes class='blocks-orange-highlight') Traverse the document in IE6 and convert all spaces in class declarations to hyphens and reapply classes based on new style name Summary: Solution 1 allows the people at this company to apply any styles in the future and the script will adjust as needed. However it does not allow for the chained style to be added, only the individual style... it is also processor intensive and time consuming, but also the most likely to be converted into a plugin that could be used the world over Solution 2 is a potential nightmare to code. But again will allow for an endless number of updates without breaking Solution 3 will require someone at the companty to hardcode the new styles every time they make a change, and if they don't, IE6 will break. Ironically the site, whilst needing to conform to IE6 in a limited manner, does not need to run wihtout javascript (they've made the call... have JS or go away), so consider all jQuery and JS solutions to be 'game on'. Did I mention how much i hate IE6? Anyway... any thoughts or comments would be appreciated. I will continue to develop my own solution and if I discover one that can be turned into a jQuery plugin I will post it here in the comments. Regards, Mike.

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  • Error Handling without Exceptions

    - by James
    While searching SO for approaches to error handling related to business rule validation , all I encounter are examples of structured exception handling. MSDN and many other reputable development resources are very clear that exceptions are not to be used to handle routine error cases. They are only to be used for exceptional circumstances and unexpected errors that may occur from improper use by the programmer (but not the user.) In many cases, user errors such as fields that are left blank are common, and things which our program should expect, and therefore are not exceptional and not candidates for use of exceptions. QUOTE: Remember that the use of the term exception in programming has to do with the thinking that an exception should represent an exceptional condition. Exceptional conditions, by their very nature, do not normally occur; so your code should not throw exceptions as part of its everyday operations. Do not throw exceptions to signal commonly occurring events. Consider using alternate methods to communicate to a caller the occurrence of those events and leave the exception throwing for when something truly out of the ordinary happens. For example, proper use: private void DoSomething(string requiredParameter) { if (requiredParameter == null) throw new ArgumentExpcetion("requiredParameter cannot be null"); // Remainder of method body... } Improper use: // Renames item to a name supplied by the user. Name must begin with an "F". public void RenameItem(string newName) { // Items must have names that begin with "F" if (!newName.StartsWith("F")) throw new RenameException("New name must begin with /"F/""); // Remainder of method body... } In the above case, according to best practices, it would have been better to pass the error up to the UI without involving/requiring .NET's exception handling mechanisms. Using the same example above, suppose one were to need to enforce a set of naming rules against items. What approach would be best? Having the method return a enumerated result? RenameResult.Success, RenameResult.TooShort, RenameResult.TooLong, RenameResult.InvalidCharacters, etc. Using an event in a controller class to report to the UI class? The UI calls the controller's RenameItem method, and then handles an AfterRename event that the controller raises and that has rename status as part of the event args? The controlling class directly references and calls a method from the UI class that handles the error, e.g. ReportError(string text). Something else... ? Essentially, I want to know how to perform complex validation in classes that may not be the Form class itself, and pass the errors back to the Form class for display -- but I do not want to involve exception handling where it should not be used (even though it seems much easier!) Based on responses to the question, I feel that I'll have to state the problem in terms that are more concrete: UI = User Interface, BLL = Business Logic Layer (in this case, just a different class) User enters value within UI. UI reports value to BLL. BLL performs routine validation of the value. BLL discovers rule violation. BLL returns rule violation to UI. UI recieves return from BLL and reports error to user. Since it is routine for a user to enter invalid values, exceptions should not be used. What is the right way to do this without exceptions?

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  • A format for storing personal contacts in a database

    - by Gart
    I'm thinking of the best way to store personal contacts in a database for a business application. The traditional and straightforward approach would be to create a table with columns for each element, i.e. Name, Telephone Number, Job title, Address, etc... However, there are known industry standards for this kind of data, like for example vCard, or hCard, or vCard-RDF/XML or even Windows Contacts XML Schema. Utilizing an standard format would offer some benefits, like inter-operablilty with other systems. But how can I decide which method to use? The requirements are mainly to store the data. Search and ordering queries are highly unlikely but possible. The volume of the data is 100,000 records at maximum. My database engine supports native XML columns. I have been thinking to use some XML-based format to store the personal contacts. Then it will be possible to utilize XML indexes on this data, if searching and ordering is needed. Is this a good approach? Which contacts format and schema would you recommend for this? Edited after first answers Here is why I think the straightforward approach is bad. This is due to the nature of this kind of data - it is not that simple. The personal contacts it is not well-structured data, it may be called semi-structured. Each contact may have different data fields, maybe even such fields which I cannot anticipate. In my opinion, each piece of this data should be treated as important information, i.e. no piece of data could be discarded just because there was no relevant column in the database. If we took it further, assuming that no data may be lost, then we could create a big text column named Comment or Description or Other and put there everything which cannot be fitted well into table columns. But then again - the data would lose structure - this might be bad. If we wanted structured data then - according to the database design principles - the data should be decomposed into entities, and relations should be established between the entities. But this adds complexity - there are just too many entities, and lots of design desicions should be made, like "How do we store Address? Personal Name? Phone number? How do we encode home phone numbers and mobile phone numbers? How about other contact info?.." The relations between entities are complex and multiple, and each relation is a table in the database. Each relation needs to be documented in the design papers. That is a lot of work to do. But it is possible to avoid the complexity entirely - just document that the data is stored according to such and such standard schema, period. Then anybody who would be reading that document should easily understand what it was all about. Finally, this is all about using an industry standard. The standard is, hopefully, designed by some clever people who anticipated and described the structure of personal contacts information much better than I ever could. Why should we all reinvent the wheel?? It's much easier to use a standard schema. The problem is, there are just too many standards - it's not easy to decide which one to use!

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  • Overriding Object.Equals() instance method in C#; now Code Analysis / FxCop warning CA2218: "should

    - by Chris W. Rea
    I've got a complex class in my C# project on which I want to be able to do equality tests. It is not a trivial class; it contains a variety of scalar properties as well as references to other objects and collections (e.g. IDictionary). For what it's worth, my class is sealed. To enable a performance optimization elsewhere in my system (an optimization that avoids a costly network round-trip), I need to be able to compare instances of these objects to each other for equality – other than the built-in reference equality – and so I'm overriding the Object.Equals() instance method. However, now that I've done that, Visual Studio 2008's Code Analysis a.k.a. FxCop, which I keep enabled by default, is raising the following warning: warning : CA2218 : Microsoft.Usage : Since 'MySuperDuperClass' redefines Equals, it should also redefine GetHashCode. I think I understand the rationale for this warning: If I am going to be using such objects as the key in a collection, the hash code is important. i.e. see this question. However, I am not going to be using these objects as the key in a collection. Ever. Feeling justified to suppress the warning, I looked up code CA2218 in the MSDN documentation to get the full name of the warning so I could apply a SuppressMessage attribute to my class as follows: [SuppressMessage("Microsoft.Naming", "CA2218:OverrideGetHashCodeOnOverridingEquals", Justification="This class is not to be used as key in a hashtable.")] However, while reading further, I noticed the following: How to Fix Violations To fix a violation of this rule, provide an implementation of GetHashCode. For a pair of objects of the same type, you must ensure that the implementation returns the same value if your implementation of Equals returns true for the pair. When to Suppress Warnings ----- Do not suppress a warning from this rule. [arrow & emphasis mine] So, I'd like to know: Why shouldn't I suppress this warning as I was planning to? Doesn't my case warrant suppression? I don't want to code up an implementation of GetHashCode() for this object that will never get called, since my object will never be the key in a collection. If I wanted to be pedantic, instead of suppressing, would it be more reasonable for me to override GetHashCode() with an implementation that throws a NotImplementedException? Update: I just looked this subject up again in Bill Wagner's good book Effective C#, and he states in "Item 10: Understand the Pitfalls of GetHashCode()": If you're defining a type that won't ever be used as the key in a container, this won't matter. Types that represent window controls, web page controls, or database connections are unlikely to be used as keys in a collection. In those cases, do nothing. All reference types will have a hash code that is correct, even if it is very inefficient. [...] In most types that you create, the best approach is to avoid the existence of GetHashCode() entirely. ... that's where I originally got this idea that I need not be concerned about GetHashCode() always.

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  • Disable antialiasing for a specific GDI device context

    - by Jacob Stanley
    I'm using a third party library to render an image to a GDI DC and I need to ensure that any text is rendered without any smoothing/antialiasing so that I can convert the image to a predefined palette with indexed colors. The third party library i'm using for rendering doesn't support this and just renders text as per the current windows settings for font rendering. They've also said that it's unlikely they'll add the ability to switch anti-aliasing off any time soon. The best work around I've found so far is to call the third party library in this way (error handling and prior settings checks ommitted for brevity): private static void SetFontSmoothing(bool enabled) { int pv = 0; SystemParametersInfo(Spi.SetFontSmoothing, enabled ? 1 : 0, ref pv, Spif.None); } // snip Graphics graphics = Graphics.FromImage(bitmap) IntPtr deviceContext = graphics.GetHdc(); SetFontSmoothing(false); thirdPartyComponent.Render(deviceContext); SetFontSmoothing(true); This obviously has a horrible effect on the operating system, other applications flicker from cleartype enabled to disabled and back every time I render the image. So the question is, does anyone know how I can alter the font rendering settings for a specific DC? Even if I could just make the changes process or thread specific instead of affecting the whole operating system, that would be a big step forward! (That would give me the option of farming this rendering out to a separate process- the results are written to disk after rendering anyway) EDIT: I'd like to add that I don't mind if the solution is more complex than just a few API calls. I'd even be happy with a solution that involved hooking system dlls if it was only about a days work. EDIT: Background Information The third-party library renders using a palette of about 70 colors. After the image (which is actually a map tile) is rendered to the DC, I convert each pixel from it's 32-bit color back to it's palette index and store the result as an 8bpp greyscale image. This is uploaded to the video card as a texture. During rendering, I re-apply the palette (also stored as a texture) with a pixel shader executing on the video card. This allows me to switch and fade between different palettes instantaneously instead of needing to regenerate all the required tiles. It takes between 10-60 seconds to generate and upload all the tiles for a typical view of the world. EDIT: Renamed GraphicsDevice to Graphics The class GraphicsDevice in the previous version of this question is actually System.Drawing.Graphics. I had renamed it (using GraphicsDevice = ...) because the code in question is in the namespace MyCompany.Graphics and the compiler wasn't able resolve it properly. EDIT: Success! I even managed to port the PatchIat function below to C# with the help of Marshal.GetFunctionPointerForDelegate. The .NET interop team really did a fantastic job! I'm now using the following syntax, where Patch is an extension method on System.Diagnostics.ProcessModule: module.Patch( "Gdi32.dll", "CreateFontIndirectA", (CreateFontIndirectA original) => font => { font->lfQuality = NONANTIALIASED_QUALITY; return original(font); }); private unsafe delegate IntPtr CreateFontIndirectA(LOGFONTA* lplf); private const int NONANTIALIASED_QUALITY = 3; [StructLayout(LayoutKind.Sequential)] private struct LOGFONTA { public int lfHeight; public int lfWidth; public int lfEscapement; public int lfOrientation; public int lfWeight; public byte lfItalic; public byte lfUnderline; public byte lfStrikeOut; public byte lfCharSet; public byte lfOutPrecision; public byte lfClipPrecision; public byte lfQuality; public byte lfPitchAndFamily; public unsafe fixed sbyte lfFaceName [32]; }

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  • TSQL Shred XML - Is this right or is there a better way (newbie @ shredding XML)

    - by drachenstern
    Ok, I'm a C# ASP.NET dev following orders: The orders are to take a given dataset, shred the XML and return columns. I've argued that it's easier to do the shredding on the ASP.NET side where we already have access to things like deserializers, etc, and the entire complex of known types, but no, the boss says "shred it on the server, return a dataset, bind the dataset to the columns of the gridview" so for now, I'm doing what I was told. This is all to head off the folks who will come along and say "bad requirements". Task at hand: Here's my code that works and does what I want it to: DECLARE @table1 AS TABLE ( ProductID VARCHAR(10) , Name VARCHAR(20) , Color VARCHAR(20) , UserEntered VARCHAR(20) , XmlField XML ) INSERT INTO @table1 SELECT '12345','ball','red','john','<sizes><size name="medium"><price>10</price></size><size name="large"><price>20</price></size></sizes>' INSERT INTO @table1 SELECT '12346','ball','blue','adam','<sizes><size name="medium"><price>12</price></size><size name="large"><price>25</price></size></sizes>' INSERT INTO @table1 SELECT '12347','ring','red','john','<sizes><size name="medium"><price>5</price></size><size name="large"><price>8</price></size></sizes>' INSERT INTO @table1 SELECT '12348','ring','blue','adam','<sizes><size name="medium"><price>8</price></size><size name="large"><price>10</price></size></sizes>' INSERT INTO @table1 SELECT '23456','auto','black','ann','<auto><type>car</type><wheels>4</wheels><doors>4</doors><cylinders>3</cylinders></auto>' INSERT INTO @table1 SELECT '23457','auto','black','ann','<auto><type>truck</type><wheels>4</wheels><doors>2</doors><cylinders>8</cylinders></auto><auto><type>car</type><wheels>4</wheels><doors>4</doors><cylinders>6</cylinders></auto>' DECLARE @x XML SELECT @x = ( SELECT ProductID , Name , Color , UserEntered , XmlField.query(' for $vehicle in //auto return <auto type = "{$vehicle/type}" wheels = "{$vehicle/wheels}" doors = "{$vehicle/doors}" cylinders = "{$vehicle/cylinders}" />') FROM @table1 table1 WHERE Name = 'auto' FOR XML AUTO ) SELECT @x SELECT ProductID = T.Item.value('../@ProductID', 'varchar(10)') , Name = T.Item.value('../@Name', 'varchar(20)') , Color = T.Item.value('../@Color', 'varchar(20)') , UserEntered = T.Item.value('../@UserEntered', 'varchar(20)') , VType = T.Item.value('@type' , 'varchar(10)') , Wheels = T.Item.value('@wheels', 'varchar(2)') , Doors = T.Item.value('@doors', 'varchar(2)') , Cylinders = T.Item.value('@cylinders', 'varchar(2)') FROM @x.nodes('//table1/auto') AS T(Item) SELECT @x = ( SELECT ProductID , Name , Color , UserEntered , XmlField.query(' for $object in //sizes/size return <size name = "{$object/@name}" price = "{$object/price}" />') FROM @table1 table1 WHERE Name IN ('ring', 'ball') FOR XML AUTO ) SELECT @x SELECT ProductID = T.Item.value('../@ProductID', 'varchar(10)') , Name = T.Item.value('../@Name', 'varchar(20)') , Color = T.Item.value('../@Color', 'varchar(20)') , UserEntered = T.Item.value('../@UserEntered', 'varchar(20)') , SubName = T.Item.value('@name' , 'varchar(10)') , Price = T.Item.value('@price', 'varchar(2)') FROM @x.nodes('//table1/size') AS T(Item) So for now, I'm trying to figure out if there's a better way to write the code than what I'm doing now... (I have a part 2 I'm about to go key in)

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  • How to query on table returned by Stored procedure within a procedure.

    - by Shantanu Gupta
    I have a stored procedure that is performing some ddl dml operations. It retrieves a data after processing data from CTE and cross apply and other such complex things. Now this returns me a 4 tables which gets binded to various sources at frontend. Now I want to use one of the table to further processing so as to get more usefull information from it. eg. This table would be containing approx 2000 records at most of which i want to get records that belongs to lodging only. PK_CATEGORY_ID DESCRIPTION FK_CATEGORY_ID IMMEDIATE_PARENT Department_ID Department_Name DESCRIPTION_HIERARCHY DEPTH IS_ACTIVE ID_PATH DESC_PATH -------------------- -------------------------------------------------- -------------------- -------------------------------------------------- -------------------- -------------------------------------------------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ----------- ----------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 1 Food NULL NULL 1 Food (Food) Food 0 1 0 Food 5 Chinese 1 Food 1 Food (Food) ----Chinese 1 1 1 Food->Chinese 14 X 5 Chinese 1 Food (Food) --------X 2 1 1->5 Food->Chinese->X 15 Y 5 Chinese 1 Food (Food) --------Y 2 1 1->5 Food->Chinese->Y 65 asdasd 5 Chinese 1 Food (Food) --------asdasd 2 1 1->5 Food->Chinese->asdasd 66 asdas 5 Chinese 1 Food (Food) --------asdas 2 1 1->5 Food->Chinese->asdas 8 Italian 1 Food 1 Food (Food) ----Italian 1 1 1 Food->Italian 48 hfghfgh 1 Food 1 Food (Food) ----hfghfgh 1 1 1 Food->hfghfgh 55 Asd 1 Food 1 Food (Food) ----Asd 1 1 1 Food->Asd 2 Lodging NULL NULL 2 Lodging (Lodging) Lodging 0 1 0 Lodging 3 Room 2 Lodging 2 Lodging (Lodging) ----Room 1 1 2 Lodging->Room 4 Floor 3 Room 2 Lodging (Lodging) --------Floor 2 1 2->3 Lodging->Room->Floor 9 First 4 Floor 2 Lodging (Lodging) ------------First 3 1 2->3->4 Lodging->Room->Floor->First 10 Second 4 Floor 2 Lodging (Lodging) ------------Second 3 1 2->3->4 Lodging->Room->Floor->Second 11 Third 4 Floor 2 Lodging (Lodging) ------------Third 3 1 2->3->4 Lodging->Room->Floor->Third 29 Fourth 4 Floor 2 Lodging (Lodging) ------------Fourth 3 1 2->3->4 Lodging->Room->Floor->Fourth 12 Air Conditioned 3 Room 2 Lodging (Lodging) --------Air Conditioned 2 1 2->3 Lodging->Room->Air Conditioned 20 With Balcony 12 Air Conditioned 2 Lodging (Lodging) ------------With Balcony 3 1 2->3->12 Lodging->Room->Air Conditioned->With Balcony 24 Mountain View 20 With Balcony 2 Lodging (Lodging) ----------------Mountain View 4 1 2->3->12->20 Lodging->Room->Air Conditioned->With Balcony->Mountain View 25 Ocean View 20 With Balcony 2 Lodging (Lodging) ----------------Ocean View 4 1 2->3->12->20 Lodging->Room->Air Conditioned->With Balcony->Ocean View 26 Garden View 20 With Balcony 2 Lodging (Lodging) ----------------Garden View 4 1 2->3->12->20 Lodging->Room->Air Conditioned->With Balcony->Garden View 52 Smoking 20 With Balcony 2 Lodging (Lodging) ----------------Smoking 4 1 2->3->12->20 Lodging->Room->Air Conditioned->With Balcony->Smoking 21 Without Balcony 12 Air Conditioned 2 Lodging (Lodging) ------------Without Balcony 3 1 2->3->12 Lodging->Room->Air Conditioned->Without Balcony 13 Non Air Conditioned 3 Room 2 Lodging (Lodging) --------Non Air Conditioned 2 1 2->3 Lodging->Room->Non Air Conditioned 22 With Balcony 13 Non Air Conditioned 2 Lodging (Lodging) ------------With Balcony 3 1 2->3->13 Lodging->Room->Non Air Conditioned->With Balcony 71 EA 3 Room 2 Lodging (Lodging) --------EA 2 1 2->3 Lodging->Room->EA 50 Casabellas 2 Lodging 2 Lodging (Lodging) ----Casabellas 1 1 2 Lodging->Casabellas 51 North Beach 50 Casabellas 2 Lodging (Lodging) --------North Beach 2 1 2->50 Lodging->Casabellas->North Beach 40 Fooding NULL NULL 40 Fooding (Fooding) Fooding 0 1 0 Fooding 41 Pizza 40 Fooding 40 Fooding (Fooding) ----Pizza 1 1 40 Fooding->Pizza 45 Onion 41 Pizza 40 Fooding (Fooding) --------Onion 2 1 40->41 Fooding->Pizza->Onion 47 Extra Cheeze 41 Pizza 40 Fooding (Fooding) --------Extra Cheeze 2 1 40->41 Fooding->Pizza->Extra Cheeze 77 Burger 40 Fooding 40 Fooding (Fooding) ----Burger 1 1 40 Fooding->Burger This result is being obtained to me using some stored procedure which contains some DML operations as well. i want something like this select description from exec spName where fk_category_id=5 Remember that this spName is returning me 4 tables of which i want to perform some query on one of the table whose index will be known to me. I dont have to send it to UI before querying further. I am using Sql Server 2008 but would like a compatible solution for 2005 also.

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  • Can't import my module when start my twisted application under root

    - by kepkin
    Here is absolutely minimal application so you could try to reproduce it on your machine. Having two files for example in /home/aln/tmp/tw_test: server.tac MyLib.py MyLib.py class Solver(object): def solve(self): """ do extremely complex stuff here """ print "Hello from solve" server.tac #!/usr/bin/python import MyLib from twisted.application import internet, service from twisted.internet import protocol, reactor, defer, utils, threads from twisted.protocols import basic class MyProtocol(basic.LineReceiver): def lineReceived(self, line): if line=="new job": self.transport.write("started a job" + '\r\n') self.factory.run_defered() class MyFactory(protocol.ServerFactory, MyLib.Solver): protocol = MyProtocol def run_defered_helper(self): self.solve() def run_defered(self): d = threads.deferToThread(self.run_defered_helper) application = service.Application('MyApplication') factory = MyFactory() internet.TCPServer(1079, factory).setServiceParent(service.IServiceCollection(application)) Everything works fine when I start it under non-root user. aln@aln-laptop:tw_test$ twistd -ny server.tac 2010-03-03 22:42:55+0300 [-] Log opened. 2010-03-03 22:42:55+0300 [-] twistd 8.2.0 (/usr/bin/python 2.6.4) starting up. 2010-03-03 22:42:55+0300 [-] reactor class: twisted.internet.selectreactor.SelectReactor. 2010-03-03 22:42:55+0300 [-] <class 'MyFactory'> starting on 1079 2010-03-03 22:42:55+0300 [-] Starting factory <MyFactory object at 0x2d5ea50> 2010-03-03 22:42:59+0300 [MyProtocol,0,127.0.0.1] Hello from solve ^C2010-03-03 22:43:01+0300 [-] Received SIGINT, shutting down. 2010-03-03 22:43:01+0300 [-] (Port 1079 Closed) 2010-03-03 22:43:01+0300 [-] Stopping factory <MyFactory object at 0x2d5ea50> 2010-03-03 22:43:01+0300 [-] Main loop terminated. 2010-03-03 22:43:02+0300 [-] Server Shut Down. But if try to start it under root (which is going to happen in my real application) I receive the following exception: aln@aln-laptop:tw_test$ sudo twistd -ny server.tac [sudo] password for aln: Traceback (most recent call last): File "/usr/lib/python2.6/dist-packages/twisted/application/app.py", line 694, in run runApp(config) File "/usr/lib/python2.6/dist-packages/twisted/scripts/twistd.py", line 23, in runApp _SomeApplicationRunner(config).run() File "/usr/lib/python2.6/dist-packages/twisted/application/app.py", line 411, in run self.application = self.createOrGetApplication() File "/usr/lib/python2.6/dist-packages/twisted/application/app.py", line 494, in createOrGetApplication application = getApplication(self.config, passphrase) --- <exception caught here> --- File "/usr/lib/python2.6/dist-packages/twisted/application/app.py", line 505, in getApplication application = service.loadApplication(filename, style, passphrase) File "/usr/lib/python2.6/dist-packages/twisted/application/service.py", line 390, in loadApplication application = sob.loadValueFromFile(filename, 'application', passphrase) File "/usr/lib/python2.6/dist-packages/twisted/persisted/sob.py", line 215, in loadValueFromFile exec fileObj in d, d File "server.tac", line 2, in <module> import MyLib exceptions.ImportError: No module named MyLib Failed to load application: No module named MyLib If I try to load MyLib module in the python intepreter under root, it works fine: aln@aln-laptop:tw_test$ sudo python Python 2.6.4 (r264:75706, Dec 7 2009, 18:43:55) [GCC 4.4.1] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import MyLib >>> import sys >>> print(sys.path) ['', '/usr/lib/python2.6', '/usr/lib/python2.6/plat-linux2', '/usr/lib/python2.6/lib-tk', '/usr/lib/python2.6/lib-old', '/usr/lib/python2.6/lib-dynload', '/usr/lib/python2.6/dist-packages', '/usr/lib/python2.6/dist-packages/PIL', '/usr/lib/python2.6/dist-packages/gst-0.10', '/usr/lib/pymodules/python2.6', '/usr/lib/python2.6/dist-packages/gtk-2.0', '/usr/lib/pymodules/python2.6/gtk-2.0', '/usr/local/lib/python2.6/dist-packages'] >>> sys.path is absolutely the same for aln user. I tried sudo -E too. Any suggestions?

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  • Where are classpath, path and pathelement documented in Ant version 1.8.0?

    - by Robert Menteer
    I'm looking over the documentation that comes with Apache Ant version 1.8.0 and can't find where classpath, path and pathelement are documented. I've found a page that describes path like structures but it doesn't list the valid attributes or nested elements for these. Another thing I can't find in the documentation is a description of the relationships between filelist, fileset, patternset and path and how to convert them back and forth. For instance there has to be an easier way to compile only those classes in one package while removing all class dependencies on the package classes and update documentation. <!-- Get list of files in which we're interested. --> <fileset id = "java.source.set" dir = "${src}"> <include name = "**/Package/*.java" /> </fileset> <!-- Get a COMMA separated list of classes to compile. --> <pathconvert property = "java.source.list" refid = "java.source.set" pathsep = ","> <globmapper from = "${src}/*.@{src.extent}" to = "*.class" /> </pathconvert> <!-- Remove ALL dependencies on package classes. --> <depend srcdir = "${src}" destdir = "${build}" includes = "${java.source.list}" closure = "yes" /> <!-- Get a list of up to date classes. --> <fileset id = "class.uptodate.set" dir = "${build}"> <include name = "**/*.class" /> </fileset> <!-- Get list of source files for up to date classes. --> <pathconvert property = "java.uptodate.list" refid = "class.uptodate.set" pathsep = ","> <globmapper from="${build}/*.class" to="*.java" /> </pathconvert> <!-- Compile only those classes in package that are not up to date. --> <javac srcdir = "${src}" destdir = "${build}" classpathref = "compile.classpath" includes = "${java.source.list}" excludes = "${java.uptodate.list}"/> <!-- Get list of directories of class files for package. --: <pathconvert property = "class.dir.list" refid = "java.source.set" pathsep = ","> <globmapper from = "${src}/*.java" to = "${build}*" /> </pathconvert> <!-- Convert directory list to path. --> <path id = "class.dirs.path"> <dirset dir = "${build}" includes = "class.dir.list" /> </path> <!-- Update package documentation. --> <jdepend outputfile = "${docs}/jdepend-report.txt"> <classpath refid = "compile.classpath" /> <classpath location = "${build}" /> <classespath> <path refid = "class.dirs.path" /> </classespath> <exclude name = "java.*" /> <exclude name = "javax.*" /> </jdepend> Notice there's a number of conversions between filesets, paths and comma separated list just to get the proper 'type' required for the different ant tasks. Is there a way to simplify this while still processing the fewest files in a complex directory structure?

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  • Problem using form builder & DOM manipulation in Rails with multiple levels of nested partials

    - by Chris Hart
    I'm having a problem using nested partials with dynamic form builder code (from the "complex form example" code on github) in Rails. I have my top level view "new" (where I attempt to generate the template): <% form_for (@transaction_group) do |txngroup_form| %> <%= txngroup_form.error_messages %> <% content_for :jstemplates do -%> <%= "var transaction='#{generate_template(txngroup_form, :transactions)}'" %> <% end -%> <%= render :partial => 'transaction_group', :locals => { :f => txngroup_form, :txn_group => @transaction_group }%> <% end -%> This renders the transaction_group partial: <div class="content"> <% logger.debug "in partial, class name = " + txn_group.class.name %> <% f.fields_for txn_group.transactions do |txn_form| %> <table id="transactions" class="form"> <tr class="header"><td>Price</td><td>Quantity</td></tr> <%= render :partial => 'transaction', :locals => { :tf => txn_form } %> </table> <% end %> <div>&nbsp;</div><div id="container"> <%= link_to 'Add a transaction', '#transaction', :class => "add_nested_item", :rel => "transactions" %> </div> <div>&nbsp;</div> ... which in turn renders the transaction partial: <tr><td><%= tf.text_field :price, :size => 5 %></td> <td><%= tf.text_field :quantity, :size => 2 %></td></tr> The generate_template code looks like this: def generate_html(form_builder, method, options = {}) options[:object] ||= form_builder.object.class.reflect_on_association(method).klass.new options[:partial] ||= method.to_s.singularize options[:form_builder_local] ||= :f form_builder.fields_for(method, options[:object], :child_index => 'NEW_RECORD') do |f| render(:partial => options[:partial], :locals => { options[:form_builder_local] => f }) end end def generate_template(form_builder, method, options = {}) escape_javascript generate_html(form_builder, method, options) end (Obviously my code is not the most elegant - I was trying to get this nested partial thing worked out first.) My problem is that I get an undefined variable exception from the transaction partial when loading the view: /Users/chris/dev/ss/app/views/transaction_groups/_transaction.html.erb:2:in _run_erb_app47views47transaction_groups47_transaction46html46erb_locals_f_object_transaction' /Users/chris/dev/ss/app/helpers/customers_helper.rb:29:in generate_html' /Users/chris/dev/ss/app/helpers/customers_helper.rb:28:in generate_html' /Users/chris/dev/ss/app/helpers/customers_helper.rb:34:in generate_template' /Users/chris/dev/ss/app/views/transaction_groups/new.html.erb:4:in _run_erb_app47views47transaction_groups47new46html46erb' /Users/chris/dev/ss/app/views/transaction_groups/new.html.erb:3:in _run_erb_app47views47transaction_groups47new46html46erb' /Users/chris/dev/ss/app/views/transaction_groups/new.html.erb:1:in _run_erb_app47views47transaction_groups47new46html46erb' /Users/chris/dev/ss/app/controllers/transaction_groups_controller.rb:17:in new' I'm pretty sure this is because the do loop for form_for hasn't executed yet (?)... I'm not sure that my approach to this problem is the best, but I haven't been able to find a better solution for dynamically adding form partials to the DOM. Basically I need a way to add records to a has_many model dynamically on a nested form. Any recommendations on a way to fix this particular problem or (even better!) a cleaner solution are appreciated. Thanks in advance. Chris

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  • Accessing py2exe program over network in Windows 98 throws ImportErrors

    - by darvids0n
    I'm running a py2exe-compiled python program from one server machine on a number of client machines (mapped to a network drive on every machine, say W:). For Windows XP and later machines, have so far had zero problems with Python picking up W:\python23.dll (yes, I'm using Python 2.3.5 for W98 compatibility and all that). It will then use W:\zlib.pyd to decompress W:\library.zip containing all the .pyc files like os and such, which are then imported and the program runs no problems. The issue I'm getting is on some Windows 98 SE machines (note: SOME Windows 98 SE machines, others seem to work with no apparent issues). What happens is, the program runs from W:, the W:\python23.dll is, I assume, found (since I'm getting Python ImportErrors, we'd need to be able to execute a Python import statement), but a couple of things don't work: 1) If W:\library.zip contains the only copy of the .pyc files, I get ZipImportError: can't decompress data; zlib not available (nonsense, considering W:\zlib.pyd IS available and works fine with the XP and higher machines on the same network). 2) If the .pyc files are actually bundled INSIDE the python exe by py2exe, OR put in the same directory as the .exe, OR put into a named subdirectory which is then set as part of the PYTHONPATH variable (e.g W:\pylib), I get ImportError: no module named os (os is the first module imported, before sys and anything else). Come to think of it, sys.path wouldn't be available to search if os was imported before it maybe? I'll try switching the order of those imports but my question still stands: Why is this a sporadic issue, working on some networks but not on others? And how would I force Python to find the files that are bundled inside the very executable I run? I have immediate access to the working Windows 98 SE machine, but I only get access to the non-working one (a customer of mine) every morning before their store opens. Thanks in advance! EDIT: Okay, big step forward. After debugging with PY2EXE_VERBOSE, the problem occurring on the specific W98SE machine is that it's not using the right path syntax when looking for imports. Firstly, it doesn't seem to read the PYTHONPATH environment variable (there may be a py2exe-specific one I'm not aware of, like PY2EXE_VERBOSE). Secondly, it only looks in one place before giving up (if the files are bundled inside the EXE, it looks there. If not, it looks in library.zip). EDIT 2: In fact, according to this, there is a difference between the sys.path in the Python interpreter and that of Py2exe executables. Specifically, sys.path contains only a single entry: the full pathname of the shared code archive. Blah. No fallbacks? Not even the current working directory? I'd try adding W:\ to PATH, but py2exe doesn't conform to any sort of standards for locating system libraries, so it won't work. Now for the interesting bit. The path it tries to load atexit, os, etc. from is: W:\\library.zip\<module>.<ext> Note the single slash after library.zip, but the double slash after the drive letter (someone correct me if this is intended and should work). It looks like if this is a string literal, then since the slash isn't doubled, it's read as an (invalid) escape sequence and the raw character is printed (giving W:\library.zipos.pyd, W:\library.zipos.dll, ... instead of with a slash); if it is NOT a string literal, the double slash might not be normpath'd automatically (as it should be) and so the double slash confuses the module loader. Like I said, I can't just set PYTHONPATH=W:\\library.zip\\ because it ignores that variable. It may be worth using sys.path.append at the start of my program but hard-coding module paths is an absolute LAST resort, especially since the problem occurs in ONE configuration of an outdated OS. Any ideas? I have one, which is to normpath the sys.path.. pity I need os for that. Another is to just append os.getenv('PATH') or os.getenv('PYTHONPATH') to sys.path... again, needing the os module. The site module also fails to initialise, so I can't use a .pth file. I also recently tried the following code at the start of the program: for pth in sys.path: fErr.write(pth) fErr.write(' to ') pth.replace('\\\\','\\') # Fix Windows 98 pathing issues fErr.write(pth) fErr.write('\n') But it can't load linecache.pyc, or anything else for that matter; it can't actually execute those commands from the looks of things. Is there any way to use built-in functionality which doesn't need linecache to modify the sys.path dynamically? Or am I reduced to hard-coding the correct sys.path?

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  • Neural Network Always Produces Same/Similar Outputs for Any Input

    - by l33tnerd
    I have a problem where I am trying to create a neural network for Tic-Tac-Toe. However, for some reason, training the neural network causes it to produce nearly the same output for any given input. I did take a look at Artificial neural networks benchmark, but my network implementation is built for neurons with the same activation function for each neuron, i.e. no constant neurons. To make sure the problem wasn't just due to my choice of training set (1218 board states and moves generated by a genetic algorithm), I tried to train the network to reproduce XOR. The logistic activation function was used. Instead of using the derivative, I multiplied the error by output*(1-output) as some sources suggested that this was equivalent to using the derivative. I can put the Haskell source on HPaste, but it's a little embarrassing to look at. The network has 3 layers: the first layer has 2 inputs and 4 outputs, the second has 4 inputs and 1 output, and the third has 1 output. Increasing to 4 neurons in the second layer didn't help, and neither did increasing to 8 outputs in the first layer. I then calculated errors, network output, bias updates, and the weight updates by hand based on http://hebb.mit.edu/courses/9.641/2002/lectures/lecture04.pdf to make sure there wasn't an error in those parts of the code (there wasn't, but I will probably do it again just to make sure). Because I am using batch training, I did not multiply by x in equation (4) there. I am adding the weight change, though http://www.faqs.org/faqs/ai-faq/neural-nets/part2/section-2.html suggests to subtract it instead. The problem persisted, even in this simplified network. For example, these are the results after 500 epochs of batch training and of incremental training. Input |Target|Output (Batch) |Output(Incremental) [1.0,1.0]|[0.0] |[0.5003781562785173]|[0.5009731800870864] [1.0,0.0]|[1.0] |[0.5003740346965251]|[0.5006347214672715] [0.0,1.0]|[1.0] |[0.5003734471544522]|[0.500589332376345] [0.0,0.0]|[0.0] |[0.5003674110937019]|[0.500095157458231] Subtracting instead of adding produces the same problem, except everything is 0.99 something instead of 0.50 something. 5000 epochs produces the same result, except the batch-trained network returns exactly 0.5 for each case. (Heck, even 10,000 epochs didn't work for batch training.) Is there anything in general that could produce this behavior? Also, I looked at the intermediate errors for incremental training, and the although the inputs of the hidden/input layers varied, the error for the output neuron was always +/-0.12. For batch training, the errors were increasing, but extremely slowly and the errors were all extremely small (x10^-7). Different initial random weights and biases made no difference, either. Note that this is a school project, so hints/guides would be more helpful. Although reinventing the wheel and making my own network (in a language I don't know well!) was a horrible idea, I felt it would be more appropriate for a school project (so I know what's going on...in theory, at least. There doesn't seem to be a computer science teacher at my school). EDIT: Two layers, an input layer of 2 inputs to 8 outputs, and an output layer of 8 inputs to 1 output, produces much the same results: 0.5+/-0.2 (or so) for each training case. I'm also playing around with pyBrain, seeing if any network structure there will work. Edit 2: I am using a learning rate of 0.1. Sorry for forgetting about that. Edit 3: Pybrain's "trainUntilConvergence" doesn't get me a fully trained network, either, but 20000 epochs does, with 16 neurons in the hidden layer. 10000 epochs and 4 neurons, not so much, but close. So, in Haskell, with the input layer having 2 inputs & 2 outputs, hidden layer with 2 inputs and 8 outputs, and output layer with 8 inputs and 1 output...I get the same problem with 10000 epochs. And with 20000 epochs. Edit 4: I ran the network by hand again based on the MIT PDF above, and the values match, so the code should be correct unless I am misunderstanding those equations. Some of my source code is at http://hpaste.org/42453/neural_network__not_working; I'm working on cleaning my code somewhat and putting it in a Github (rather than a private Bitbucket) repository. All of the relevant source code is now at https://github.com/l33tnerd/hsann.

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  • Rx IObservable buffering to smooth out bursts of events

    - by Dan
    I have an Observable sequence that produces events in rapid bursts (ie: five events one right after another, then a long delay, then another quick burst of events, etc.). I want to smooth out these bursts by inserting a short delay between events. Imagine the following diagram as an example: Raw: --oooo--------------ooooo-----oo----------------ooo| Buffered: --o--o--o--o--------o--o--o--o--o--o--o---------o--o--o| My current approach is to generate a metronome-like timer via Observable.Interval() that signals when it's ok to pull another event from the raw stream. The problem is that I can't figure out how to then combine that timer with my raw unbuffered observable sequence. IObservable.Zip() is close to doing what I want, but it only works so long as the raw stream is producing events faster than the timer. As soon as there is a significant lull in the raw stream, the timer builds up a series of unwanted events that then immediately pair up with the next burst of events from the raw stream. Ideally, I want an IObservable extension method with the following function signature that produces the bevaior I've outlined above. Now, come to my rescue StackOverflow :) public static IObservable<T> Buffered(this IObservable<T> src, TimeSpan minDelay) PS. I'm brand new to Rx, so my apologies if this is a trivially simple question... 1. Simple yet flawed approach Here's my initial naive and simplistic solution that has quite a few problems: public static IObservable<T> Buffered<T>(this IObservable<T> source, TimeSpan minDelay) { Queue<T> q = new Queue<T>(); source.Subscribe(x => q.Enqueue(x)); return Observable.Interval(minDelay).Where(_ => q.Count > 0).Select(_ => q.Dequeue()); } The first obvious problem with this is that the IDisposable returned by the inner subscription to the raw source is lost and therefore the subscription can't be terminated. Calling Dispose on the IDisposable returned by this method kills the timer, but not the underlying raw event feed that is now needlessly filling the queue with nobody left to pull events from the queue. The second problem is that there's no way for exceptions or end-of-stream notifications to be propogated through from the raw event stream to the buffered stream - they are simply ignored when subscribing to the raw source. And last but not least, now I've got code that wakes up periodically regardless of whether there is actually any work to do, which I'd prefer to avoid in this wonderful new reactive world. 2. Way overly complex appoach To solve the problems encountered in my initial simplistic approach, I wrote a much more complicated function that behaves much like IObservable.Delay() (I used .NET Reflector to read that code and used it as the basis of my function). Unfortunately, a lot of the boilerplate logic such as AnonymousObservable is not publicly accessible outside the system.reactive code, so I had to copy and paste a lot of code. This solution appears to work, but given its complexity, I'm less confident that its bug free. I just can't believe that there isn't a way to accomplish this using some combination of the standard Reactive extensions. I hate feeling like I'm needlessly reinventing the wheel, and the pattern I'm trying to build seems like a fairly standard one.

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  • Ant + JUnit: NoClassDefFoundError

    - by K-Boo
    Ok, I'm frustrated! I've hunted around for a good number of hours and am still stumped. Environment: WinXP, Eclipse Galileo 3.5 (straight install - no extra plugins). So, I have a simple JUnit test. It runs fine from it's internal Eclipse JUnit run configuration. This class has no dependencies on anything. To narrow this problem down as much as possible it simply contains: @Test public void testX() { assertEquals("1", new Integer(1).toString()); } No sweat so far. Now I want to take the super advanced step of running this test case from within Ant (the final goal is to integrate with Hudson). So, I create a build.xml: <project name="Test" default="basic"> <property name="default.target.dir" value="${basedir}/target" /> <property name="test.report.dir" value="${default.target.dir}/test-reports" /> <target name="basic"> <mkdir dir="${test.report.dir}" /> <junit fork="true" printSummary="true" showOutput="true"> <formatter type="plain" /> <classpath> <pathelement path="${basedir}/bin "/> </classpath> <batchtest fork="true" todir="${test.report.dir}" > <fileset dir="${basedir}/bin"> <include name="**/*Test.*" /> </fileset> </batchtest> </junit> </target> </project> ${basedir} is the Java project name in the workspace that contains the source, classes and build file. All .java's and the build.xml are in ${basedir}/src. The .class files are in ${basedir}/bin. I have added eclipse-install-dir/plugins/org.junit4_4.5.0.v20090423/junit.jar to the Ant Runtime Classpath via Windows / Preferences / Ant / Runtime / Contributed Entries. ant-junit.jar is in Ant Home Entries. So, what happens when I run this insanely complex target? My report file contains: Testsuite: com.xyz.test.RussianTest Tests run: 1, Failures: 0, Errors: 1, Time elapsed: 0 sec Testcase: initializationError took 0 sec Caused an ERROR org/hamcrest/SelfDescribing java.lang.NoClassDefFoundError: org/hamcrest/SelfDescribing at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(Unknown Source) at java.security.SecureClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.access$000(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClassInternal(Unknown Source) at java.lang.reflect.Constructor.newInstance(Unknown Source) Caused by: java.lang.ClassNotFoundException: org.hamcrest.SelfDescribing at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClassInternal(Unknown Source) What is this org.hamcrest.SelfDescribing class? Something to do with mocks? OK, fine. But why the dependency? I'm not doing anything at all with it. This is literally a Java project with no dependencies other than JUnit. Stumped (and frustrated)!!

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  • Recursive XSD Help

    - by Alon
    Hi, i'm trying to learn a little bit XSD and I'm trying to create a XSD for this xml: <Document> <TextBox Name="Username" /> <TextBox Name="Password" /> </Document> ... so there's an element, which is an abstract complex type. Every element have elements and so on. Document and TextBox are extending Element. I trid this: <?xml version="1.0" encoding="utf-8" ?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="Document"> <xs:complexType> <xs:complexContent> <xs:extension base="Element"> </xs:extension> </xs:complexContent> </xs:complexType> </xs:element> <xs:complexType name="Element" abstract="true"> <xs:sequence minOccurs="0" maxOccurs="unbounded"> <xs:element name="Element" type="Element"></xs:element> </xs:sequence> </xs:complexType> <xs:complexType name="TextBox"> <xs:complexContent> <xs:extension base="Element"> <xs:attribute name="Name" type="xs:string" /> </xs:extension> </xs:complexContent> </xs:complexType> </xs:schema> I compiled it to C# with Xsd2Code, and now I try to deserialize it: var serializer = new XmlSerializer(typeof(Document)); var document = (Document)serializer.Deserialize(new FileStream("Document1.xml", FileMode.Open)); foreach (var element in document.Element1) { Console.WriteLine(((TextBox)element).Name); } Console.ReadLine(); and it dosen't print anything. When I try to serialize it like so: var serializer = new XmlSerializer(typeof(Document)); var document = new Document(); document.Element1 = new List<Element>(); document.Element1.Add(new TextBox() { Name = "abc" }); serializer.Serialize(new FileStream("d.xml", FileMode.Create), document); ...the output is: <?xml version="1.0"?> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Element1> <Element xsi:type="TextBox"> <Element1 /> <Name>abc</Name> </Element> </Element1> </Document> When it should be: <Document> <TextBox Name="abc" /> </Document> Any ideas how to fix the xsd or another code generator? Thanks.

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  • PPTP ping client to client error

    - by Linux Intel
    I installed pptp server on a centos 6 64bit server PPTP Server ip : 55.66.77.10 PPTP Local ip : 10.0.0.1 Client1 IP : 10.0.0.60 centos 5 64bit Client2 IP : 10.0.0.61 centos5 64bit PPTP Server can ping Client1 And client 1 can ping PPTP Server PPTP Server can ping Client2 And client 2 can ping PPTP Server The problem is client 1 can not ping Client 2 route -n on PPTP Server Destination Gateway Genmask Flags Metric Ref Use Iface 10.0.0.60 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0 10.0.0.61 0.0.0.0 255.255.255.255 UH 0 0 0 ppp1 55.66.77.10 0.0.0.0 255.255.255.248 U 0 0 0 eth0 10.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 eth0 0.0.0.0 55.66.77.19 0.0.0.0 UG 0 0 0 eth0 route -n On Client 1 Destination Gateway Genmask Flags Metric Ref Use Iface 10.0.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0 55.66.77.10 70.14.13.19 255.255.255.255 UGH 0 0 0 eth0 10.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 eth1 0.0.0.0 70.14.13.19 0.0.0.0 UG 0 0 0 eth0 route -n On Client 2 Destination Gateway Genmask Flags Metric Ref Use Iface 10.0.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0 55.66.77.10 84.56.120.60 255.255.255.255 UGH 0 0 0 eth1 10.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 eth0 0.0.0.0 84.56.120.60 0.0.0.0 UG 0 0 0 eth1 cat /etc/ppp/options.pptpd on PPTP server ############################################################################### # $Id: options.pptpd,v 1.11 2005/12/29 01:21:09 quozl Exp $ # # Sample Poptop PPP options file /etc/ppp/options.pptpd # Options used by PPP when a connection arrives from a client. # This file is pointed to by /etc/pptpd.conf option keyword. # Changes are effective on the next connection. See "man pppd". # # You are expected to change this file to suit your system. As # packaged, it requires PPP 2.4.2 and the kernel MPPE module. ############################################################################### # Authentication # Name of the local system for authentication purposes # (must match the second field in /etc/ppp/chap-secrets entries) name pptpd # Strip the domain prefix from the username before authentication. # (applies if you use pppd with chapms-strip-domain patch) #chapms-strip-domain # Encryption # (There have been multiple versions of PPP with encryption support, # choose with of the following sections you will use.) # BSD licensed ppp-2.4.2 upstream with MPPE only, kernel module ppp_mppe.o # {{{ refuse-pap refuse-chap refuse-mschap # Require the peer to authenticate itself using MS-CHAPv2 [Microsoft # Challenge Handshake Authentication Protocol, Version 2] authentication. require-mschap-v2 # Require MPPE 128-bit encryption # (note that MPPE requires the use of MSCHAP-V2 during authentication) require-mppe-128 # }}} # OpenSSL licensed ppp-2.4.1 fork with MPPE only, kernel module mppe.o # {{{ #-chap #-chapms # Require the peer to authenticate itself using MS-CHAPv2 [Microsoft # Challenge Handshake Authentication Protocol, Version 2] authentication. #+chapms-v2 # Require MPPE encryption # (note that MPPE requires the use of MSCHAP-V2 during authentication) #mppe-40 # enable either 40-bit or 128-bit, not both #mppe-128 #mppe-stateless # }}} # Network and Routing # If pppd is acting as a server for Microsoft Windows clients, this # option allows pppd to supply one or two DNS (Domain Name Server) # addresses to the clients. The first instance of this option # specifies the primary DNS address; the second instance (if given) # specifies the secondary DNS address. #ms-dns 10.0.0.1 #ms-dns 10.0.0.2 # If pppd is acting as a server for Microsoft Windows or "Samba" # clients, this option allows pppd to supply one or two WINS (Windows # Internet Name Services) server addresses to the clients. The first # instance of this option specifies the primary WINS address; the # second instance (if given) specifies the secondary WINS address. #ms-wins 10.0.0.3 #ms-wins 10.0.0.4 # Add an entry to this system's ARP [Address Resolution Protocol] # table with the IP address of the peer and the Ethernet address of this # system. This will have the effect of making the peer appear to other # systems to be on the local ethernet. # (you do not need this if your PPTP server is responsible for routing # packets to the clients -- James Cameron) proxyarp # Normally pptpd passes the IP address to pppd, but if pptpd has been # given the delegate option in pptpd.conf or the --delegate command line # option, then pppd will use chap-secrets or radius to allocate the # client IP address. The default local IP address used at the server # end is often the same as the address of the server. To override this, # specify the local IP address here. # (you must not use this unless you have used the delegate option) #10.8.0.100 # Logging # Enable connection debugging facilities. # (see your syslog configuration for where pppd sends to) debug # Print out all the option values which have been set. # (often requested by mailing list to verify options) #dump # Miscellaneous # Create a UUCP-style lock file for the pseudo-tty to ensure exclusive # access. lock # Disable BSD-Compress compression nobsdcomp # Disable Van Jacobson compression # (needed on some networks with Windows 9x/ME/XP clients, see posting to # poptop-server on 14th April 2005 by Pawel Pokrywka and followups, # http://marc.theaimsgroup.com/?t=111343175400006&r=1&w=2 ) novj novjccomp # turn off logging to stderr, since this may be redirected to pptpd, # which may trigger a loopback nologfd # put plugins here # (putting them higher up may cause them to sent messages to the pty) cat /etc/ppp/options.pptp on Client1 and Client2 ############################################################################### # $Id: options.pptp,v 1.3 2006/03/26 23:11:05 quozl Exp $ # # Sample PPTP PPP options file /etc/ppp/options.pptp # Options used by PPP when a connection is made by a PPTP client. # This file can be referred to by an /etc/ppp/peers file for the tunnel. # Changes are effective on the next connection. See "man pppd". # # You are expected to change this file to suit your system. As # packaged, it requires PPP 2.4.2 or later from http://ppp.samba.org/ # and the kernel MPPE module available from the CVS repository also on # http://ppp.samba.org/, which is packaged for DKMS as kernel_ppp_mppe. ############################################################################### # Lock the port lock # Authentication # We don't need the tunnel server to authenticate itself noauth # We won't do PAP, EAP, CHAP, or MSCHAP, but we will accept MSCHAP-V2 # (you may need to remove these refusals if the server is not using MPPE) refuse-pap refuse-eap refuse-chap refuse-mschap # Compression # Turn off compression protocols we know won't be used nobsdcomp nodeflate # Encryption # (There have been multiple versions of PPP with encryption support, # choose which of the following sections you will use. Note that MPPE # requires the use of MSCHAP-V2 during authentication) # # Note that using PPTP with MPPE and MSCHAP-V2 should be considered # insecure: # http://marc.info/?l=pptpclient-devel&m=134372640219039&w=2 # https://github.com/moxie0/chapcrack/blob/master/README.md # http://technet.microsoft.com/en-us/security/advisory/2743314 # http://ppp.samba.org/ the PPP project version of PPP by Paul Mackarras # ppp-2.4.2 or later with MPPE only, kernel module ppp_mppe.o # If the kernel is booted in FIPS mode (fips=1), the ppp_mppe.ko module # is not allowed and PPTP-MPPE is not available. # {{{ # Require MPPE 128-bit encryption #require-mppe-128 # }}} # http://mppe-mppc.alphacron.de/ fork from PPP project by Jan Dubiec # ppp-2.4.2 or later with MPPE and MPPC, kernel module ppp_mppe_mppc.o # {{{ # Require MPPE 128-bit encryption #mppe required,stateless # }}} IPtables are stopped on clients and server, Also net.ipv4.ip_forward = 1 is enabled on PPTP Server. How can i solve this problem .?

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  • Paging, sorting and filtering in a stored procedure (SQL Server)

    - by Fruitbat
    I was looking at different ways of writing a stored procedure to return a "page" of data. This was for use with the asp ObjectDataSource, but it could be considered a more general problem. The requirement is to return a subset of the data based on the usual paging paremeters, startPageIndex and maximumRows, but also a sortBy parameter to allow the data to be sorted. Also there are some parameters passed in to filter the data on various conditions. One common way to do this seems to be something like this: [Method 1] ;WITH stuff AS ( SELECT CASE WHEN @SortBy = 'Name' THEN ROW_NUMBER() OVER (ORDER BY Name) WHEN @SortBy = 'Name DESC' THEN ROW_NUMBER() OVER (ORDER BY Name DESC) WHEN @SortBy = ... ELSE ROW_NUMBER() OVER (ORDER BY whatever) END AS Row, ., ., ., FROM Table1 INNER JOIN Table2 ... LEFT JOIN Table3 ... WHERE ... (lots of things to check) ) SELECT * FROM stuff WHERE (Row > @startRowIndex) AND (Row <= @startRowIndex + @maximumRows OR @maximumRows <= 0) ORDER BY Row One problem with this is that it doesn't give the total count and generally we need another stored procedure for that. This second stored procedure has to replicate the parameter list and the complex WHERE clause. Not nice. One solution is to append an extra column to the final select list, (SELECT COUNT(*) FROM stuff) AS TotalRows. This gives us the total but repeats it for every row in the result set, which is not ideal. [Method 2] An interesting alternative is given here (http://www.4guysfromrolla.com/articles/032206-1.aspx) using dynamic SQL. He reckons that the performance is better because the CASE statement in the first solution drags things down. Fair enough, and this solution makes it easy to get the totalRows and slap it into an output parameter. But I hate coding dynamic SQL. All that 'bit of SQL ' + STR(@parm1) +' bit more SQL' gubbins. [Method 3] The only way I can find to get what I want, without repeating code which would have to be synchronised, and keeping things reasonably readable is to go back to the "old way" of using a table variable: DECLARE @stuff TABLE (Row INT, ...) INSERT INTO @stuff SELECT CASE WHEN @SortBy = 'Name' THEN ROW_NUMBER() OVER (ORDER BY Name) WHEN @SortBy = 'Name DESC' THEN ROW_NUMBER() OVER (ORDER BY Name DESC) WHEN @SortBy = ... ELSE ROW_NUMBER() OVER (ORDER BY whatever) END AS Row, ., ., ., FROM Table1 INNER JOIN Table2 ... LEFT JOIN Table3 ... WHERE ... (lots of things to check) SELECT * FROM stuff WHERE (Row > @startRowIndex) AND (Row <= @startRowIndex + @maximumRows OR @maximumRows <= 0) ORDER BY Row (Or a similar method using an IDENTITY column on the table variable). Here I can just add a SELECT COUNT on the table variable to get the totalRows and put it into an output parameter. I did some tests and with a fairly simple version of the query (no sortBy and no filter), method 1 seems to come up on top (almost twice as quick as the other 2). Then I decided to test probably I needed the complexity and I needed the SQL to be in stored procedures. With this I get method 1 taking nearly twice as long as the other 2 methods. Which seems strange. Is there any good reason why I shouldn't spurn CTEs and stick with method 3? UPDATE - 15 March 2012 I tried adapting Method 1 to dump the page from the CTE into a temporary table so that I could extract the TotalRows and then select just the relevant columns for the resultset. This seemed to add significantly to the time (more than I expected). I should add that I'm running this on a laptop with SQL Server Express 2008 (all that I have available) but still the comparison should be valid. I looked again at the dynamic SQL method. It turns out I wasn't really doing it properly (just concatenating strings together). I set it up as in the documentation for sp_executesql (with a parameter description string and parameter list) and it's much more readable. Also this method runs fastest in my environment. Why that should be still baffles me, but I guess the answer is hinted at in Hogan's comment.

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  • Dispatcher Timer Problem

    - by will
    I am trying to make a game in silverlight that also has widgets in it. To do this I am using a dispatcher timer running a game loop that updates graphics etc. In this I have a variable that has to be accessed by both by the constantly running game loop and UI event code. At first look it seemed that the gameloop had its own local copy of currentUnit (the variable), despite the variable being declared globally. I am trying to update currentUnit with an event by the widget part of the app, but the timer's version of the variable is not being updated. What can I do get the currentUnit in the gameloop loop to be updated whenever I update currentUnit via a click event? Here is the code for setting currentUnit as part of a click event DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(Unit)); currentUnit = serializer.ReadObject(e.Result) as Unit; txtName.Text = currentUnit.name; Canvas.SetLeft(txtName, 100 - (int)Math.Ceiling(txtName.ActualWidth) / 2); txtX.Text = "" + currentUnit.x; txtY.Text = "" + currentUnit.y; txtX.Text = "" + currentUnit.owner; txtY.Text = "" + currentUnit.moved; txtName.Text = "" + currentUnit.GetHashCode(); And here is a snippet from the gameLoop loop //deal with phase changes and showing stuff if (txtPhase.Text == "Move" && movementPanel.Visibility == Visibility.Collapsed) { if (currentUnit != null) { if (currentUnit.owner) { if (currentUnit.moved) { txtMoved.Text = "This Unit has Already Moved!"; movementPanel.Visibility = Visibility.Collapsed; } else { txtMoved.Text = "" + currentUnit.GetHashCode(); movementPanel.Visibility = Visibility.Visible; } } else { txtMoved.Text = "bam"; movementPanel.Visibility = Visibility.Collapsed; } } else { txtMoved.Text = "slam"; movementPanel.Visibility = Visibility.Collapsed; } //loadUnitList(); } Here is the code for my unit class. using System; public class Unit { public int id { get; set; } public string name { get; set; } public string image { get; set; } public int x { get; set; } public int y { get; set; } public bool owner { get; set; } public int rotation { get; set; } public double movement { get; set; } public string type { get; set; } public bool moved { get; set; } public bool fired { get; set; } } Overall, any simple types, like a double is being 'updated' correctly, yet a complex of my own type (Unit) seems to be holding a local copy. Please help, I've asked other places and no one has had an answer for me!

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  • Boost::Spirit::Qi autorules -- avoiding repeated copying of AST data structures

    - by phooji
    I've been using Qi and Karma to do some processing on several small languages. Most of the grammars are pretty small (20-40 rules). I've been able to use autorules almost exclusively, so my parse trees consist entirely of variants, structs, and std::vectors. This setup works great for the common case: 1) parse something (Qi), 2) make minor manipulations to the parse tree (visitor), and 3) output something (Karma). However, I'm concerned about what will happen if I want to make complex structural changes to a syntax tree, like moving big subtrees around. Consider the following toy example: A grammar for s-expr-style logical expressions that uses autorules... // Inside grammar class; rule names match struct names... pexpr %= pand | por | var | bconst; pand %= lit("(and ") >> (pexpr % lit(" ")) >> ")"; por %= lit("(or ") >> (pexpr % lit(" ")) >> ")"; pnot %= lit("(not ") >> pexpr >> ")"; ... which leads to parse tree representation that looks like this... struct var { std::string name; }; struct bconst { bool val; }; struct pand; struct por; struct pnot; typedef boost::variant<bconst, var, boost::recursive_wrapper<pand>, boost::recursive_wrapper<por>, boost::recursive_wrapper<pnot> > pexpr; struct pand { std::vector<pexpr> operands; }; struct por { std::vector<pexpr> operands; }; struct pnot { pexpr victim; }; // Many Fusion Macros here Suppose I have a parse tree that looks something like this: pand / ... \ por por / \ / \ var var var var (The ellipsis means 'many more children of similar shape for pand.') Now, suppose that I want negate each of the por nodes, so that the end result is: pand / ... \ pnot pnot | | por por / \ / \ var var var var The direct approach would be, for each por subtree: - create pnot node (copies por in construction); - re-assign the appropriate vector slot in the pand node (copies pnot node and its por subtree). Alternatively, I could construct a separate vector, and then replace (swap) the pand vector wholesale, eliminating a second round of copying. All of this seems cumbersome compared to a pointer-based tree representation, which would allow for the pnot nodes to be inserted without any copying of existing nodes. My question: Is there a way to avoid copy-heavy tree manipulations with autorule-compliant data structures? Should I bite the bullet and just use non-autorules to build a pointer-based AST (e.g., http://boost-spirit.com/home/2010/03/11/s-expressions-and-variants/)?

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  • wpftoolkit DataGridTemplateColumn Template binding

    - by Guillaume
    I want my datagrid columns to share a cell/celledit template. I have the solution do that (thanks to WPF DataGridTemplateColumn shared template?). Now what I would love to is improving the readability by avoiding all the node nesting. My current view looks like that: <wpftk:DataGrid ItemsSource="{Binding Tests}" AutoGenerateColumns="False"> <wpftk:DataGrid.Resources> <DataTemplate x:Key="CustomCellTemplate"> <TextBlock Text="{TemplateBinding Content}"/> </DataTemplate> <DataTemplate x:Key="CustomCellEditingTemplate"> <TextBox Text="{TemplateBinding Content}"></TextBox> </DataTemplate> </wpftk:DataGrid.Resources> <wpftk:DataGrid.Columns> <wpftk:DataGridTemplateColumn Header="Start Date"> <wpftk:DataGridTemplateColumn.CellTemplate> <DataTemplate> <ContentPresenter ContentTemplate="{StaticResource CustomCellTemplate}" Content="{Binding StartDate}"/> </DataTemplate> </wpftk:DataGridTemplateColumn.CellTemplate> <wpftk:DataGridTemplateColumn.CellEditingTemplate> <DataTemplate> <ContentPresenter ContentTemplate="{StaticResource CustomCellEditingTemplate}" Content="{Binding StartDate}"/> </DataTemplate> </wpftk:DataGridTemplateColumn.CellEditingTemplate> </wpftk:DataGridTemplateColumn> <!--and again the whole block above for each columns...--> </wpftk:DataGrid.Columns> </wpftk:DataGrid> What I would like to achieve is to bind the value at the DataGridTemplateColumn level and propagate it to the template level. Anyone know how to do that? What I tried to do is something like that: <wpftk:DataGrid ItemsSource="{Binding Tests}" AutoGenerateColumns="False"> <wpftk:DataGrid.Resources> <DataTemplate x:Key="CustomCellTemplate"> <TextBlock Text="{Binding}"/> </DataTemplate> <DataTemplate x:Key="CustomCellEditingTemplate"> <TextBox Text="{Binding}"></TextBox> </DataTemplate> </wpftk:DataGrid.Resources> <wpftk:DataGrid.Columns> <wpftk:DataGridTemplateColumn Header="Start Date" Binding="{Binding StartDate}" CellTemplate="{StaticResource CustomCellTemplate}" CellEditingTemplate="{StaticResource CustomCellEditingTemplate}"/> <wpftk:DataGridTemplateColumn Header="End Date" Binding="{Binding EndDate}" CellTemplate="{StaticResource CustomCellTemplate}" CellEditingTemplate="{StaticResource CustomCellEditingTemplate}"/> </wpftk:DataGrid.Columns> </wpftk:DataGrid> Obviously the binding porperty is not a valid property of the DataGridTemplateColumn but maybe by playing with the datacontext and some relative source could do the trick but frankly I can't find a way to implement that. Not sure if what I want is possible and i'm willing to accept a "no way you can do that" as an answer NOTE: The TextBlock/TextBox in the template is just for test (the real template is much more complex) DataGridTextColumn will not do the trick Thanks in advance

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