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  • How can I create two contructors that act differently but recieve the same data type?

    - by Sergio Tapia
    public class Parser { Downloader download = new Downloader(); HtmlDocument Page; public Parser(string MovieTitle) { Page = download.FindMovie(MovieTitle); } public Parser(string ActorName) { Page = download.FindActor(ActorName); } } I want to create a constructor that will allow other developers who use this library to easily create a Parser object with the relevant HtmlDocument already loaded as soon as it's done creating it. The problem lies in that a constructor cannot exist twice with the same type of parameters. Sure I can tell the logical difference between the two paramters, but the computer can't. Any suggestions on how to handle this? Thank you!

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  • Update mapping table in Linq

    - by Gary McGill
    I have a table Customers with a CustomerId field, and a table of Publications with a PublicationId field. Finally, I have a mapping table CustomersPublications that records which publications a customer can access - it has two fields: CustomerId field PublicationId. For a given customer, I want to update the CustomersPublications table based on a list of publication ids. I want to remove records in CustomersPublications where the PublicationId is not in the list, and add new records where the PublicationId is in the list but not already in the table. This would be easy in SQL, but I can't figure out how to do it in Linq. For the delete part, I tried: var recordsToDelete = dataContext.CustomersPublications.Where ( cp => (cp.CustomerId == customerId) && ! publicationIds.Contains(cp.PublicationId) ); dataContext.CustomersPublications.DeleteAllOnSubmit(recordsToDelete); ... but that didn't work. I got an error: System.NotSupportedException: Method 'Boolean Contains(Int32)' has no supported translation to SQL So, I tried using Any(), as follows: var recordsToDelete = dataContext.CustomersPublications.Where ( cp => (cp.CustomerId == customerId) && ! publicationIds.Any(p => p == cp.PublicationId) ); ... and this just gives me another error: System.NotSupportedException: Local sequence cannot be used in LINQ to SQL implementation of query operators except the Contains() operator Any pointers? [I have to say, I find Linq baffling (and frustrating) for all but the simplest queries. Better error messages would help!]

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  • rails: has_many :through validation?

    - by ramonrails
    Rails 2.1.0 (Cannot upgrade for now due to several constraints) I am trying to achieve this. Any hints? A project has many users through join model A user has many projects through join model Admin class inherits User class. It also has some Admin specific stuff. Admin like inheritance for Supervisor and Operator Project has one Admin, One supervisor and many operators. Now I want to 1. submit data for project, admin, supervisor and operator in a single project form 2. validate all and show errors on the project form. Project has_many :projects_users ; has_many :users, :through => :projects_users User has_many :projects_users ; has_many :projects, :through => :projects_users ProjectsUser = :id integer, :user_id :integer, :project_id :integer, :user_type :string ProjectUser belongs_to :project, belongs_to :user Admin < User # User has 'type:string' column for STI Supervisor < User Operator < User Is the approach correct? Any and all suggestions are welcome.

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  • Get the number of calendar weeks between 2 dates in C#

    - by Phil Scholtes
    For the purposes of this question, let's assume the user will be from the US and will use the standard Gregorian calendar. So, a calendar week starts on Sunday and ends on Saturday. What I'm trying to do is determine the number of calendar weeks that exist between two dates. A perfect example of my problem exists in October 2010. Between 10/16 and 10/31 there are 4 calendar weeks. View a picture of October 2010 October 10 - October 16 October 17 - October 23 October 24 - October 30 October 31 - November 6 I'd prefer to stay away from any hardcoded logic like: if (Day == DayOfWeek.Saturday && LastDayOfMonth == 31) { ... } Can anyone think of a logical way to do this?

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  • Should I unit test my JavaScript?

    - by Joseph Silvashy
    I'm curious to if it would be valuable, I'd like to start using QUnit, but I really don't know where to get started. Actually I'm not going to lie, I'm new to testing in general, not just with JS. I'm hoping to get some tips to how I would start using unit testing with an app that already has a large amount of JavaScript (ok so about 500 lines, not huge, be enough to make me wonder if I have regression that goes unnoticed). How would you recommend getting started and Where would I write my tests? (for example its rails app, where is a logical place to have my JS tests, it would be cool if they could go in the /test directory but it's outside the public directory and thus not possible... err is it?)

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  • Java JFileChooser getAbsoluteFile Add File Extension

    - by ikurtz
    i have this issue working but i would like to know if there is a better way of adding the file extension? what i am doing right now is: String filePath = chooser.getSelectedFile().getAbsoluteFile() + ".html"; im adding the extension hard coded. and then saving to it. just wondering if there is a more robust/logical manner this can be implemented? thank you for your time. EDIT: i ask this as i would like my app to be portable across platforms. so adding .html manually i may make this a windows only solution.

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  • What's your preferred pointer declaration style, and why?

    - by Owen
    I know this is about as bad as it gets for "religious" issues, as Jeff calls them. But I want to know why the people who disagree with me on this do so, and hear their justification for their horrific style. I googled for a while and couldn't find a style guide talking about this. So here's how I feel pointers (and references) should be declared: int* pointer = NULL; int& ref = *pointer; int*& pointer_ref = pointer; The asterisk or ampersand goes with the type, because it modifies the type of the variable being declared. EDIT: I hate to keep repeating the word, but when I say it modifies the type I'm speaking semantically. "int* something;" would translate into English as something like "I declare something, which is a pointer to an integer." The "pointer" goes along with the "integer" much more so than it does with the "something." In contrast, the other uses of the ampersand and asterisk, as address-of and dereferencing operators, act on a variable. Here are the other two styles (maybe there are more but I really hope not): int *ugly_but_common; int * uglier_but_fortunately_less_common; Why? Really, why? I can never think of a case where the second is appropriate, and the first only suitable perhaps with something like: int *hag, *beast; But come now... multiple variable declarations on one line is kind of ugly form in itself already.

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  • How to Import a CSV file containing multiple sections into R?

    - by PaulHurleyuk
    I want to import the contents of a csv file into R, the csv file contains multiple sections of data vertically, seperated by blank lines and asterisks. For example ******************************************************** * SAMPLE DATA ****************************************** ******************************************************** Name, DOB, Sex Rod, 1/1/1970, M Jane, 5/7/1980, F Freddy, 9.12,1965, M ******************************************************* * Income Data **************************************** ******************************************************* Name, Income Rod, 10000 Jane, 15000 Freddy, 7500 I would like to import this into R as two seperate dataframes. Currently I'm manually cutting the csv file up into smaller files, but I think I could do it using read.csv and the skip and nrows settings of read.csv, If I could work out where the secion breaks are. This gives me a logical TRUE for every blank line ifelse(readLines("DATA.csv")=="",TRUE,FALSE) I'm hoping someone has already solved this problem.

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  • Speech.Recognition GrammarBuilder/Choices Tree Structure

    - by user2210179
    In playing around with C#'s Speech Recognition, I've stumbled across a road block in the creation of an effective GrammerBuilder with Choices (more specifically, Choices of Choices). IE considering the following logical commands. One solution would to "hard code" every combination of Speech lines and add them to a GrammarBuilder (ie "SET LEFT COLOR RED" and "SET RIGHT CLEAR", however, this would quickly max out the limit of 1024, especially when dealing with number combinations. Another solution would to Append all 'columns' as "Choices" (and filter out incorrect paths upon 'recognition', however this seems like it's processor heavy and unnecessary. The middle ground, seems like the best path - with Choices of Choices - like a tree structure on a GrammarBuilder - however I'm not sure how to proceed. Any suggestions?

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  • Curious about python installation paths, especially on OSX.

    - by chiggsy
    First: I'm running Macports. No problems with that, except: /opt/local/Library/Frameworks/Python.framework/Versions/2.6/bin which is the value of sys.exec_prefix, for my macports python even though: /opt/local/lib/python2.6/site-packages/ seems to be quite a logical place to put things, /opt/local being the macports --prefix, as it were. Why does easy_install put things in this odd Frameworks/Python.framework thing? More importantly, can i use the methods here, to ensure that all my systemwide python, particularly the scripts which I really want in /opt/local/bin, things I use all over the place like (i|b)python for example are accessible?

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  • Objective-C convention to prevent "local declaration hides instance variable" warning

    - by Nippysaurus
    Is there a common convention for dealing with these scenarios? The following code is what I am using .. -(id) initWithVariableName: (NSString*)variableName withComparisonValue:(NSString*)comparisonValue { self.mustExist = NO; self.reverseCondition = NO; self.regularExpression = NO; self.variableName = variableName; self.comparisonValue = comparisonValue; return self; } But I am getting "Local declaration of 'variableName' hides instance variable" and the same for "comparisonValue". The function signature seems logical to me, but surely there must be a more "acceptable" standard which will still make sense and be accurate but not generate annoying warnings?

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  • Python/Tkinter Audio Player

    - by Nicholas Quirk
    Hey everyone reading this, I've recently got into doing GUI development with Python. Tkinter seems like the easiest and most logical choice starting out. I did a little with wxPython but it was more sophisticated than what I needed. Anyway, I'm developing a media player. Right now it's a simple window with a button to load .wav files. The problem is I would like to implement a pause button now. But, when playing a audio file the GUI isn't accessible again (no buttons can be pushed) till the file is done playing. How can I make the GUI dynamic while an audio file is playing? I was thinking this maybe be because I'm using PyAudio, and their implementation doesn't allow this. Anyway, thanks for any advice before hand.

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  • How does a programmer think?

    - by Gordon Potter
    This may be a hopelessly vague question. But I am interested to hear whatever logical thought processes people go through when learning a new concept or trying to get their brain around code they might not have ever seen before. Basically, what general steps does one take to to break down problems and what does it take to "get it"? If you were to diagram a flowchart of how your mental process works when you look at code or try to solve a problem what might it look like? What common references, tips, and mental assumptions do you find useful in problem solving? How is this different between different domains? For example in what ways is a web programmer's thought process similar or different from a traditional desktop app developer's process?

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  • Difference between try-finally and try-catch

    - by Vijay Kotari
    What's the difference between try { fooBar(); } finally { barFoo(); } and try { fooBar(); } catch(Throwable throwable) { barFoo(throwable); // Does something with throwable, logs it, or handles it. } I like the second version better because it gives me access to the Throwable. Is there any logical difference or a preferred convention between the two variations? Also, is there a way to access the exception from the finally clause?

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  • construct test environment for web application on PC - directory issues

    - by ernie
    I have a site that physically has this directory structure. -public_html --conf > contains file conf.php -SiteFiles -LiveSite > contains file ConfLive.php Directory public_html/conf/ contains a file called conf.php this file contains the following include include_once('/home/mydir/SiteFiles/LiveSite/conf/ConfLive.iphp'); I want to copy this application to test PC to test it. Test PC uses XAMPP Apache. "Root" directory on the test machine is: C:\xampp\htdocs\ My questions: 1. Where is logical path "/home/mydir/" defined? 2. What steps should I take to get this to work on my test machine preferably by server configuration and not changing application. Thanks. (PS maybe this question is better posed at Server Overflow site.)

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  • heterogeneous comparisons in python3

    - by Matt Anderson
    I'm 99+% still using python 2.x, but I'm trying to think ahead to the day when I switch. So, I know that using comparison operators (less/greater than, or equal to) on heterogeneous types that don't have a natural ordering is no longer supported in python3.x -- instead of some consistent (but arbitrary) result we raise TypeError instead. I see the logic in that, and even mostly think its a good thing. Consistency and refusing to guess is a virtue. But what if you essentially want the python2.x behavior? What's the best way to go about getting it? For fun (more or less) I was recently implementing a Skip List, a data structure that keeps its elements sorted. I wanted to use heterogeneous types as keys in the data structure, and I've got to compare keys to one another as I walk the data structure. The python2.x way of comparing makes this really convenient -- you get an understandable ordering amongst elements that have a natural ordering, and some ordering amongst those that don't. Consistently using a sort/comparison key like (type(obj).__name__, obj) has the disadvantage of not interleaving the objects that do have a natural ordering; you get all your floats clustered together before your ints, and your str-derived class separates from your strs. I came up with the following: import operator def hetero_sort_key(obj): cls = type(obj) return (cls.__name__+'_'+cls.__module__, obj) def make_hetero_comparitor(fn): def comparator(a, b): try: return fn(a, b) except TypeError: return fn(hetero_sort_key(a), hetero_sort_key(b)) return comparator hetero_lt = make_hetero_comparitor(operator.lt) hetero_gt = make_hetero_comparitor(operator.gt) hetero_le = make_hetero_comparitor(operator.le) hetero_ge = make_hetero_comparitor(operator.gt) Is there a better way? I suspect one could construct a corner case that this would screw up -- a situation where you can compare type A to B and type A to C, but where B and C raise TypeError when compared, and you can end up with something illogical like a > b, a < c, and yet b > c (because of how their class names sorted). I don't know how likely it is that you'd run into this in practice.

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  • Finding recurrence relations of an algorithm

    - by Roarke
    I'm reading my algorithms text book, and I'm reading about recurrence relations and finding the algorithms big O complexity. I run across this line "In the case of the merge-sort algorithm, we get the recurrence equation: t(n) = b if n < 2 = 2t(n/2) +bn if n >= 2 for b > 0 my response was "how the heck did we know that?!?!" So i'm wondering if there is a systematic approach, or just a logical way of getting these recurrence relations from the algorithms can some one explain where the b and the two 2's come from?

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  • Optimal password salt length

    - by Juliusz Gonera
    I tried to find the answer to this question on Stack Overflow without any success. Let's say I store passwords using SHA-1 hash (so it's 160 bits) and let's assume that SHA-1 is enough for my application. How long should be the salt used to generated password's hash? The only answer I found was that there's no point in making it longer than the hash itself (160 bits in this case) which sounds logical, but should I make it that long? E.g. Ubuntu uses 8-byte salt with SHA-512 (I guess), so would 8 bytes be enough for SHA-1 too or maybe it would be too much?

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  • Python threads all executing on a single core

    - by Rob Lourens
    I have a Python program that spawns many threads, runs 4 at a time, and each performs an expensive operation. Pseudocode: for object in list: t = Thread(target=process, args=(object)) # if fewer than 4 threads are currently running, t.start(). Otherwise, add t to queue But when the program is run, Activity Monitor in OS X shows that 1 of the 4 logical cores is at 100% and the others are at nearly 0. Obviously I can't force the OS to do anything but I've never had to pay attention to performance in multi-threaded code like this before so I was wondering if I'm just missing or misunderstanding something. Thanks.

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  • Encrypt text using a number

    - by Adam Matan
    Project Euler I have recently begun to solve some of the Project Euler riddles. I found the discussion forum in the site a bit frustrating (most of the discussions are closed and poorly-threaded), So I have decided to publish my Python solutions on launchpad for discussion. The problem is that it seems quite unethical to publish these solutions, as it would let other people gain reputation without doing the programming work, which the site deeply discourages. My Encryption problem I want to encrypt my answers so that only those who have already solved the riddles can see my code. The logical key would be the answer to the riddle, which is always numeric. In order to prevent brute-force attacks on my answers, I want to find an encryption algorithm that takes a significantly long time (few seconds) to run. Do you know any such algorithm? I would fancy a Python package, which I can attach to the code, over an external program that might have portability issues. Thanks, Adam

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  • Why will this code compile using ifort compiler and not when using gfortran compiler? Help!

    - by CuriousCompiler
    I'm rewriting some code to make a program compile with the gfortran compiler as opposed to ifort compiler I usually use. The code follows: _Subroutine SlideBits (WORD, BITS, ADDR) Implicit None Integer(4) WORD Integer(4) BITS Integer(4) ADDR Integer(4) ADDR1 ADDR1 = 32 - ADDR WORD = (WORD .And. (.Not.ISHFT(1,ADDR1))) .Or. ISHFT(BITS,ADDR1) End_ When I compile the above code using the gfortran compiler, I recieve this error: WORD = (WORD .And. (.Not.ISHFT(1,ADDR1))) .Or. ISHFT(BITS,ADDR1) Error: Operand of .NOT. operator at (1) is INTEGER(4) All three of the variables coming into the subroutine are integers. I've looked around a bit and the gfortran wiki states that the gfortran compiler should be able to handle logical statments being applied to integer values. Several other sites I've visited either quote from the gnu wiki or agree with it. This is the first time I've seen this error as the Intel Fortran compiler (ifort) I normally use compiles cleanly.

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  • LINQ to SQL - How to efficiently do either an AND or an OR search for multiple criteria

    - by Dan Diplo
    I have an ASP.NET MVC site (which uses Linq To Sql for the ORM) and a situation where a client wants a search facility against a bespoke database whereby they can choose to either do an 'AND' search (all criteria match) or an 'OR' search (any criteria match). The query is quite complex and long and I want to know if there is a simple way I can make it do both without having to have create and maintain two different versions of the query. For instance, the current 'AND' search looks something like this (but this is a much simplified version): private IQueryable<SampleListDto> GetSampleSearchQuery(SamplesCriteria criteria) { var results = from r in Table where (r.Id == criteria.SampleId) && (r.Status.SampleStatusId == criteria.SampleStatusId) && (r.Job.JobNumber.StartsWith(criteria.JobNumber)) && (r.Description.Contains(criteria.Description)) select r; } I could copy this and replace the && with || operators to get the 'OR' version, but feel there must be a better way of achieving this. Does anybody have any suggestions how this can be achieved in an efficient and flexible way that is easy to maintain? Thanks.

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  • In Django, why is user.is_authenticated a method and not a member variable like is_staff

    - by luc
    Hello all, I've lost some time with a bug in my app due to user authentication. I think that it's a bit confusing but maybe someone can explain the reason and it will appear to me very logical. The user.is_staff is a member variable while user.is_authenticated is a method. However is_authenticated only returns True or False depending if the class is User or AnonymousUser (see http://docs.djangoproject.com/en/dev/topics/auth/) Is there a reason for that? Why user.is_authenticated is a method? Thanks in advance

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  • What is a Web Framework ? How does it compare with LAMP

    - by Nishant
    I started web development in LAMP/WAMP and it was logical to me . There is a Web Server program called Apache which does the networking part of setting up a service on port 80 ( common port ) . If the request is regular HTML it uses the HTTP headers to transport files .And if the request for the file is a PHP one , it has a mod_php with which Apache invokes the PHP interpreter to process the file and it gives back HTML which is again transferred as usual HTML . Now the question is what is a Web Framework ? I came across Python based website creation and there is Flask . What is a flask , how does it compare with LAMP . Further are DJango / Ruby on Rails different from flask ? Can someone answer me and also give some good places to read on these .Thanks for your answers in advance . Further is things like LAMP slower than the common FRAMEWORKS because they claimn easy deplyment fo web apps .

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  • Flipping issue when interpolating Rotations using Quaternions

    - by uhuu
    I use slerp to interpolate between two quaternions representing rotations. The resulting rotation is then extracted as Euler angles to be fed into a graphics lib. This kind of works, but I have the following problem; when rotating around two (one works just fine) axes in the direction of the green arrow as shown in the left frame here the rotation soon jumps around to rotate from the opposite site to the opposite visual direction, as indicated by the red arrow in the right frame. This may be logical from a mathematical perspective (although not to me), but it is undesired. How could I achieve an interpolation with no visual flipping and changing of directions when rotating around more than one axis, following the green arrow at all times until the interpolation is complete? Thanks in advance.

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