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• Library for Dataflow in C

  - by msutherl

  How can I do dataflow (pipes and filters, stream processing, flow based) in C? And not with UNIX pipes. I recently came across stream.py. Streams are iterables with a pipelining mechanism to enable data-flow programming and easy parallelization. The idea is to take the output of a function that turns an iterable into another iterable and plug that as the input of another such function. While you can already do this using function composition, this package provides an elegant notation for it by overloading the operator. I would like to duplicate a simple version of this kind of functionality in C. I particularly like the overloading of the operator to avoid function composition mess. Wikipedia points to this hint from a Usenet post in 1990. Why C? Because I would like to be able to do this on microcontrollers and in C extensions for other high level languages (Max, Pd*, Python). * (ironic given that Max and Pd were written, in C, specifically for this purpose – I'm looking for something barebones)

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• Syncronizing indices of function pointer table to table contents

  - by Thomas Matthews

  In the embedded system I'm working on, we are using a table of function pointers to support proprietary Dynamic Libraries. We have a header file that uses named constants (#define) for the function pointer indices. These values are used in calculating the location in the table of the function's address. Example: *(export_table.c)* // Assume each function in the table has an associated declaration typedef void (*Function_Ptr)(void); Function_Ptr Export_Function_Table[] = { 0, Print, Read, Write, Process, }; Here is the header file: *export_table.h* #define ID_PRINT_FUNCTION 1 #define ID_READ_FUNCTION 2 #define ID_WRITE_FUNCTION 3 #define ID_PROCESS_FUNCTION 4 I'm looking for a scheme to define the named constants in terms of their location in the array so that when the order of the functions changes, the constants will also change. (Also, I would like the compiler or preprocessor to calculate the indices to avoid human mistakes like typeo's.)

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• How do you compose DataTemplates / link to a child datatemplate in WPF?

  - by Gishu

  Here's the problem. Given a large/intricate datatemplate A, which has 3 sections - General, Properties, Misc. Imagine 3 grids for each. Now I need to reuse the Properties section of the above Datatemplate in another place. Reasons: To avoid redundancy + ensure that further updates to the datatemplate are applied identically to all usages. So I guess what I am asking for is an ability to slot in a link to a child DataTemplate in a parent Datatemplate. What's the best way to go about this ? I found one way to do this.. but I'm not sure if its the right way or the best.. Posting it as an answer below so that it can be rated.

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• Multiple levels of 'collection.defaultdict' in Python

  - by Morlock

  Thanks to some great folks on SO, I discovered the possibilities offered by collections.defaultdict, notably in readability and speed. I have put them to use with success. Now I would like to implement three levels of dictionaries, the two top ones being defaultdict and the lowest one being int. I don't find the appropriate way to do this. Here is my attempt: from collections import defaultdict d = defaultdict(defaultdict) a = [("key1", {"a1":22, "a2":33}), ("key2", {"a1":32, "a2":55}), ("key3", {"a1":43, "a2":44})] for i in a: d[i[0]] = i[1] Now this works, but the following, which is the desired behavior, doesn't: d["key4"]["a1"] + 1 I suspect that I should have declared somewhere that the second level defaultdict is of type int, but I didn't find where or how to do so. The reason I am using defaultdict in the first place is to avoid having to initialize the dictionary for each new key. Any more elegant suggestion? Thanks pythoneers!

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• How to Execute Base Class's Method Before Implementors's Method?

  - by DaveDev

  I have the following page public partial class GenericOfflineCommentary : OfflineFactsheetBase { } where OfflineFactsheetBase is defined as public class OfflineFactsheetBase : System.Web.UI.Page { public OfflineFactsheetBase() { this.Load += new EventHandler(this.Page_Load); this.PreInit += new EventHandler(this.Page_PreInit); } protected void Page_PreInit(object sender, EventArgs e) { if (Request.QueryString["data"] != null) { this.PageData = StringCompressor.DecompressString(Request.QueryString["data"]); this.ExtractPageData(); } } } OfflineFactsheetBase has the following virtual method: public virtual void ExtractPageData() { // get stuff relevant to all pages that impmement OfflineFactsheetBase } which is implemented in all pages that impmement OfflineFactsheetBase as follows: public partial class GenericOfflineCommentary : OfflineFactsheetBase { public override void ExtractPageData() { // get stuff relevant to an OfflineCommentary page. } } Currently, only GenericOfflineCommentary's ExtractPageData() is firing. How can I modify this to first run OfflineFactsheetBase's ExtractPageData() and then GenericOfflineCommentary's? edit: I'm trying to avoid having to call base.ExtractPageData() in every implementor. Is this possible?

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• Insert into ... Select *, how to ignore identity?

  - by Haoest

  I have a temp table with the exact structure of a concrete table T. It was created like this: select top 0 * into #tmp from T After processing and filling in content into #tmp, I want to copy the content back to T like this: insert into T select * from #tmp This is okay as long as T doesn't have identity column, but in my case it does. Is there anyways I can ignore the auto-increment identity column from #tmp when I copy to T? My motivation is to avoid having to spell out every column name in the Insert Into list. EDIT: toggling identity_insert wouldn't work because the pkeys in #tmp may collide with those in T if rows were inserted into T outside of my script, that's if #tmp has auto-incremented the pkey to sync with T's in the first place.

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• Detect if an assembly is available

  - by jgaa

  I'm implementing an installer in Java, that is supposed to download and install an application for non-privileged users in Windows (from XP and up). The application is written in C++, and depend on the usual VC runtime-libraries (msvcm90.dll and friends). In order to save bandwidth, I want to avoid downloading the VC redistributables if they already are available for the user. I do however have a problem finding a reliable method to detect if an assembly is installed. If the assembly is missing, I will deploy it as described here: http://msdn.microsoft.com/en-us/library/ms235291%28VS.80%29.aspx So the question is simply how to detect if a (any) assembly is installed on the machine. It's no requirement that this can be done from Java. I can easily write a small probe in C++ and link it statically for the task. jgaa

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• How to automatically check out a database file in a source controlled web application ?

  - by TheRHCP

  Hello, I am working on an ASP.NET web application, we are a small team (4 students) and we do not have access to a dedicated server to host the database instance. So for this web application we decided just to put the database file in the App_Data folder. The problem is that our project is source controled on TFS, so every time you open the solution and try to launch the web application, we get an expcetion saying that database is read-only. That is logical because the databse file is not automatically checked-out. Is there a workaround to avoid a manual check-out of the database file everytime we open the solution ? Thanks.

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• How do I determine the cause of Qt's "*** is not a valid Qt plugin" error?

  - by chadjoan

  When I print the value of errorString from my QPluginLoader object, I get this: The file 'C:/pyprojects/test/qsqlpsqld4.dll' is not a valid Qt plugin. I would like to avoid some days worth of doing the time consuming "guess-and-check" methodology that my current internet searches reveal (so far none of them seem relevant anyways). Is there a way for me to get the Qt library itself to tell me why it is refusing to load this plugin? I don't want to guess; I want to know. Context: I am on Windows 7 running Qt 4.8.5 (32-bit, MinGW) and the qsqlpsqld4.dll file is also 32-bit and compiled with MinGW. I am using PySide to interact with Qt.

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• Three boolean values saved in one tinyint

  - by Casper

  Hello, probably a simple question but I seem to be suffering from programmer's block. :) I have three boolean values: A, B, and C. I would like to save the state combination as an unsigned tinyint (max 255) into a database and be able to derive the states from the saved integer. Even though there are only a limited number of combinations, I would like to avoid hard-coding each state combination to a specific value (something like if A=true and B=true has the value 1). I tried to assign values to the variables so (A=1, B=2, C=3) and then adding, but I can't differentiate between A and B being true from i.e. only C being true. I am stumped but pretty sure that it is possible. Thanks

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• Why isn't it possible to update an ObservableCollection from a different thread?

  - by MainMa

  In a multi-threaded WPF application, it is not possible to update an ObservableCollection from a thread other than WPF window thread. I know there are workarounds, so my question is not how to avoid the "This type of CollectionView does not support changes to its SourceCollection from a thread different from the Dispatcher thread" exception. My question is, why there is such an exception? Why wasn't it possible to allow collection updates from any thread? Personally, I don't see any reason to block UI update when ObservableCollection is changed from other threads. If two threads (including parallel ones) are accessing the same object, one listening for changes of object properties through events, the other one doing changes, it will always work, at least if locks are used properly. So, what are the reasons?

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• Jquery Accordion and multiple slideshows

  - by Dipesh Parmar

  I've been using a lot of slideshows recently on my sites and one thing thats puzzled me is using more than one slideshow per page. I'm currently working on my own site, experimenting with Jquery Accordion. I've managed to adopt a very simple javascript slideshow, see below: http://dvpwebdesign.com/test/accordion/blank.html However i'm unable to either incorporate or use a different multiple slideshow plugin. I dont need slideshow navigation, so the The Cycle plugin works really well and i know you can use multiple slideshows. But if i either use Cycle alongside the current javascript slideshow, or only use the Cycle slideshow to avoid any possible conflict, the Accordion menu stops working. I just cant see what i am doing wrong, can anyone help?

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• How to match the word in jquery

  - by Mirage

  I have the image and i am fade in and fade out the image on click. But i want that if the same is present then it should not fadein/fadeout. My jquery code is switch(current_id) { case 'l1': $("#left_img img").fadeOut(500, function() { $(this).attr("src","rrr.gif").load( function() { $(this).fadeIn(500); }); }); break; case 'l3': $("#left_img img").fadeOut(500, function() { $(this).attr("src","cc1.gif").load( function() { $(this).fadeIn(500); }); }); break; If i click on link 1 then image A appears with fade effect. but if i click again link 1 agan , then again i see fade effect . Is there any way i can avoid that if same link is clicked again

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• Prevent Erroneous Property Assignment

  - by Gordon

  Porting android applications to iphone applications always gives me the following pattern that I accidentally create: - (void) myFunc:(id)prop { self.property = property; } Which instead should be: - (void) myFunc:(id)prop { self.property = prop; } This always causes my program to quietly break because property gets reset to its existing value rather than being set to the new value, 'prop'. I cannot name the parameter 'prop' to 'property' since the compile complains that the parameter masks the instance variables visibility. Is there a good way to avoid this situation? There are no compiler warnings. Is there a way to make xcode prevent this? I cannot see very many situations where you would set a property to the value of its underlying instance variable (maybe to trigger a KVO binding?), but I don't see myself doing that in majority of cases. I understand the above code is synthetic and should be done with @synthesize, but I am just using it as a simplified example to illustrate my point.

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• Database(Partitions) related query.... Please suggest..........

  - by AGeek

  The Query is as follows:- We have an oracle schema, with tables partitioned. -- Need to make one of the partition offline. (How to achieve this,, or have thought of assigning each partition, a different tablespace, and then making that tablespace offline) any other way out possible so as to avoid making so many tablespaces???? -- Then, copy the data files/ logs related to that partition to the temporary storage..... how to achieve this thing... any docs related to the same.... -- Then We make this partition / related tablespace online... -- Then we create a second schema with the same tables as above..... -- Copy the partition data from temporary storage to this table. (How this can be achieved,,, any specific doc??? -- Then verifying to the data is accessible in all respects..... If possible, let's discuss to find out the solution........ Thanks....

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• How can I force a subscriber to be synchronized from a local snapshot?

  - by Brian

  Hello, I have a SQL 2005 server replicating(merge\push) to SQL 2005 and SQL 2000 servers. I have multiple subscribers spread througout the United states. I have set , @snapshot_in_defaultfolder = N'false', @alt_snapshot_folder = N'c:\snapshots\Merge\' (sample location). I take the snapshot from the publisher that is in the same location, 'c:\snapshots\Merge\', and copy it to the subscribers. I wanted to avoid applying the snapshot over the WAN but from the performance I am getting the synchronization is going over the WAN. Does anybody have any ideas how to make sure that I am using the local copy of the snapshot and not the copy at the publisher? Thanks

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• Patterns for avoiding jQuery silent fails

  - by Matias

  Is there any good practice to avoid your jQuery code silently fail? For example: $('.this #is:my(complexSelector)').doSomething(); I know that every time this line get executed, the selector is intended to match at least one element, or certain amount of elements. Is there any standard or good way to validate that? I thought about something like this: var $matchedElements = $('.this #is:my(complexSelector)'); if ($matchedElements.length < 0) throw 'No matched elements'; $matchedElements.doSomething(); Also I think unit testing would be a valid option instead of messing the code. My question may be silly, but I wonder whether there is a better option than the things that I'm currently doing or not. Also, maybe I'm in the wrong way checking if any element match my selector. However, as the page continues growing, the selectors could stop matching some elements and pieces of functionality could stop working inadvertently.

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• Use a function in a conditions hash

  - by Pierre

  Hi, I'm building a conditions hash to run a query but I'm having a problem with one specific case: conditions2 = ['extract(year from signature_date) = ?', params[:year].to_i] unless params[:year].blank? conditions[:country_id] = COUNTRIES.select{|c| c.geography_id == params[:geographies]} unless params[:geographies].blank? conditions[:category_id] = CATEGORY_CHILDREN[params[:categories].to_i] unless params[:categories].blank? conditions[:country_id] = params[:countries] unless params[:countries].blank? conditions['extract(year from signature_date)'] = params[:year].to_i unless params[:year].blank? But the last line breaks everything, as it gets interpreted as follows: AND ("negotiations"."extract(year from signature_date)" = 2010 Is there a way to avoid that "negotiations"." is prepended to my condition? thank you, P.

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• Custom inputAccessoryView push my UITableView first row partially off the screen

  - by TonyMocha

  Hi For my scenario, I have a UITableView with a UITextField for the first row. While I try to set custom toolbar for keyboard with UITextField.inputAccessoryView, it pushed my first row of textfield partially off the screen. This is not happening if I avoid adding the toolbar. Refer screen shot below: I tried with NSNotification with keyboardWillShow by reposition to first row of the tableview, but it just look awkward for the table pulling out and in. It might be something to do overriding UITableView/UIScrollView, but I am out of idea how to do this. Would like to know how you guys resolve this. Thanks you!

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• What is tha CAUSE of Error 523 and Error 200 in Blackberry handhelds

  - by voipsecuritydigest.com

  I'm Blackberry developer, customers using my application experiencing Error 523 and Error 200. Remedies to those errors are in first case - remove application, my application. In second case totally reload OS! This is very bad, and customers blame me! But this is I don't do anything illegal to make blackberry crash. I just used a lot of memory, which is obvious because customer want that. Everywhere including Blackberry knowledge base people talking how to fix the problem, which may happened to everybody using application from well known brands, for example Yahoo! finances. But nobody explains what is the mechanism behind this, and if it is possible to avoid the problem. I would like to know what is that CAUSE of Error 523 and Error 200?

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• What does "static" mean in the context of declaring global template functions?

  - by smf68

  I know what static means in the context of declaring global non-template functions (see e.g. What is a "static" function?), which is useful if you write a helper function in a header that is included from several different locations and want to avoid "duplicate definition" errors. So my question is: What does static mean in the context of declaring global template functions? Please note that I'm specifically asking about global, non-member template functions that do not belong to a class. In other words, what is the difference between the following two: template <typename T> void foo(T t) { /* implementation of foo here */ } template <typename T> static void bar(T t) { /* implementation of bar here */ }

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• Status corresponding to Minimum value

  - by Lijo

  Hi Team, I am using SQL Server 2005. I have a table as given below. There can be multiple cancellations for each FundingID. I want to select the FundingCancellationReason corrersponding to minimum date for each funding. I wrote a query as follows. It is an SQL error 1) Could you please help me to avoid the SQL Error? 2) Is there any better logic to achieve the same? CREATE TABLE #FundingCancellation( [FundingCancellationID] INT IDENTITY(1,1) NOT NULL, [FundingID] INT , FundingCancellationDt SMALLDATETIME , FundingCancellationReason VARCHAR(50) ) SELECT FundingID, MIN(FundingCancellationDt), ( SELECT FundingCancellationReason FROM #FundingCancellation FC2 WHERE FC1.FundingID = FC2.FundingID AND FC2.FundingCancellationDt = MIN(FundingCancellationDt) ) [Reason Corresponding Minimum Date] FROM #FundingCancellation FC1 GROUP BY FundingID -- An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference. I have seen the similar approach working in a somewhat complex query. So I believe tehre will be a way to correct my query Thanks Lijo

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• replacing values in formated file with python

  - by froggy

  I have a string see attached file like that and i would like to modify it using a function Giving section name parameter name and value to set Also in case i want to modify several parameters for a same section how can i have position in file to avoid scanning x time for a same section and other to pass my question and other to pass my question and other to pass my question and other to pass my question and other to pass my question and other to pass my question and other to pass my question and other to pass my question and other to pass my question and other to pass my question and other to pass my question an and other to pass my question d other to pass my question and other to pass my question and other to pass my question and other to pass my questionand other to pass my question and other to pass my question

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• Rails has_one vs belongs_to semantics

  - by Anurag

  I have a model representing a Content item that contains some images. The number of images are fixed as these image references are very specific to the content. For example, the Content model refers to the Image model twice (profile image, and background image). I am trying to avoid a generic has_many, and sticking to multiple has_one's. The current database structure looks like: contents - id:integer - integer:profile_image_id - integer:background_image_id images - integer:id - string:filename - integer:content_id I just can't figure out how to setup the associations correctly here. The Content model could contain two belongs_to references to an Image, but that doesn't seem semantically right cause ideally an image belongs to the content, or in other words, the content has two images. This is the best I could think of (by breaking the semantics): class Content belongs_to :profile_image, :class_name => 'Image', :foreign_key => 'profile_image_id' belongs_to :background_image, :class_name => 'Image', :foreign_key => 'background_image_id' end Am I way off, and there a better way to achieve this association?

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• deleting a large number of rows from a table

  - by Azeem

  We have a requirement to delete rows in the order of millions from multiple tables as a batch job (note that we are not deleting all the rows, we are deleting based on a timestamp stored in an indexed column). Obviously a normal DELETE takes forever (because of logging, referential constraint checking etc.). I know in the LUW world, we have ALTER TABLE NOT LOGGED INITIALLY but I can't seem to find the an equivalent SQL statement for DB2 v8 z/OS. Any one has any ideas on how to do this really fast? Also, any ideas on how to avoid the referential checks when deleting the rows? Please let me know.

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