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  • SWT TabFolder: Weird Drawing Behaviour

    - by JesperGJensen
    Hello StackOverflow Experts Description I have an SWT Page with a TabFolder with a number of dynamically created TabItems. On each TabItem i crate a Composite and set the TabItem.setControl() to the Composite. I then use this Composite as the page on which i draw my items. I draw a set of Controls, including Textbox's and Labels. For the First, Default Tab, this works fine. No problems. Problem On tabs that is not the first tab i have the following problems: I am unable to visually alter then Edited/Enabled state of my Controls. I am unable to visually set the Text content of my elements My Controls look disabled and have a Greyed out look. But i am able to Select the content with my mouse and use CTRL+C to copy it out. So the text contet is there and they are Editable. Visually it is just not updated. Any comments are appeciated, Any requests for code, examples will be supplied and help Welcommed. Updates I tried added the suggest debug loop to the code, where i attempt to enable my Controls. This was the result: [main] INFO [dk.viking.controller.LayerController] - f038.stklok is now Editable [true] and enabled [true] [main] INFO [dk.viking.controller.LayerController] - true Text {} [main] INFO [dk.viking.controller.LayerController] - true Composite {} [main] INFO [dk.viking.controller.LayerController] - true TabFolder {} [main] INFO [dk.viking.controller.LayerController] - true Shell {Viking GUI}

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  • Collision detections and how efficient they are

    - by Shadow
    How exactly do you implement collision detection? What are the costs involved? Do different platforms(c/c++, java, cocoa/iphone, flash, directX) have different optimizations for calculating collisions. And lastly are there libraries available to do this for me, or some that I can just interpret for my platform of choice? As I understand it you would need to loop through the collision map and find the area in question and then compair the input thing(e.g. a sprite) to the type of pixel that is in the questioned area. I understand the very basic idea, but I don't understand the underlying implementation or even a higher level one for that matter. It would seem that this type of detection, or any for that matter, is very costly. Tile map? Bit array? How are these created from an image(I would guess looping and doing stuff)? The reason I ask this question is to get a better understanding of the efficiency behind the scenes and to understand exactly what is going on. Links, references, or examples would be very helpful. I know this question is a bit longwinded so any help or references would be very welcome. Thanks SO!

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  • Practical rules for premature optimization

    - by DougW
    It seems that the phrase "Premature Optimization" is the buzz-word of the day. For some reason, iphone programmers in particular seem to think of avoiding premature optimization as a pro-active goal, rather than the natural result of simply avoiding distraction. The problem is, the term is beginning to be applied more and more to cases that are completely inappropriate. For example, I've seen a growing number of people say not to worry about the complexity of an algorithm, because that's premature optimization (eg http://stackoverflow.com/questions/2190275/help-sorting-an-nsarray-across-two-properties-with-nssortdescriptor/2191720#2191720). Frankly, I think this is just laziness, and appalling to disciplined computer science. But it has occurred to me that maybe considering the complexity and performance of algorithms is going the way of assembly loop unrolling, and other optimization techniques that are now considered unnecessary. What do you think? Are we at the point now where deciding between an O(n^n) and O(n!) complexity algorithm is irrelevant? What about O(n) vs O(n*n)? What do you consider "premature optimization"? What practical rules do you use to consciously or unconsciously avoid it? This is a bit vague, but I'm curious to hear other peoples' opinions on the topic.

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  • Looping and recursion based on parameter passed

    - by contactkx
    I have an XML organized like below- <section name="Parent 1 Text here" ID="1" > <section name="Child 1 Text here" ID="11"> </section> <section name="Child 2 Text here" ID="12"> <section name="GrandChild Text here" ID="121" > </section> </section> </section> <section name="Parent 2 Text here" ID="2" > <section name="Child 1 Text here" ID="22"> </section> <section name="Child 2 Text here" ID="23"> <section name="GrandChild Text here" ID="232" > </section> </section> </section> I have to produce the below output XML - <section name="Parent 1 Text here" ID="1" > <section name="Child 2 Text here" ID="12"> <section name="GrandChild Text here" ID="121" > </section> </section> </section> <section name="Parent 2 Text here" ID="2" > <section name="Child 2 Text here" ID="23"> </section> </section> I have to achive above using XSLT 1.0 transformation. I was planning to pass a comma separated string as a parameter with value= "1,12,121,2,23" My question- How to loop the comma separated parameter in XSLT 1.0 ? Is there a simpler way to achieve the above. Please remember I have to do this in XSLT 1.0 Your help is appreciated.

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  • Android getting XML values

    - by Nils
    Hello, I have the following XML code, which I got by a UPnP device and like to get the res value - the RTSP URL. In this case rtsp://10.42.0.103:554/live.sdp How can I do this? I heard that Android has some built-in support for reading XML. Is that true? <DIDL-Lite xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:upnp="urn:schemas-upnp-org:metadata-1-0/upnp/"> <item id="11" parentID="1" restricted="1"> <dc:title>Network Camera Stream 1</dc:title> <upnp:class>object.item.videoItem</upnp:class> <res protocolInfo="rtsp-rtp-udp:*:video/mpeg4-generic:*" resolution="640x480">rtsp://10.42.0.103:554/live.sdp</res> </item> <item id="12" parentID="1" restricted="1"> <dc:title>Network Camera Stream 2</dc:title> <upnp:class>object.item.videoItem</upnp:class> <res protocolInfo="rtsp-rtp-udp:*:video/mpeg4-generic:*" resolution="176x144">rtsp://10.42.0.103:554/live2.sdp</res> </item> </DIDL-Lite>

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  • Creating nested arrays on the fly

    - by adardesign
    I am trying to do is to loop this HTML and get a nested array of this HTML values that i want to grab. It might look complex at first but is a simple question... This script is just part of a Object containing methods. html <div class="configureData"> <div title="Large"> <a href="yellow" title="true" rel="$55.00" name="sku22828"></a> <a href="green" title="true" rel="$55.00" name="sku224438"></a> <a href="Blue" title="true" rel="$55.00" name="sku22222"></a> </div> <div title="Medium"> <a href="yellow" title="true" rel="$55.00" name="sku22828"></a> <a href="green" title="true" rel="$55.00" name="sku224438"></a> <a href="Blue" title="true" rel="$55.00" name="sku22222"></a> </div> <div title="Small"> <a href="yellow" title="true" rel="$55.00" name="sku22828"></a> <a href="green" title="true" rel="$55.00" name="sku224438"></a> <a href="Blue" title="true" rel="$55.00" name="sku22222"></a> </div> </div> javascript // this is part of a script..... parseData:function(dH){ dH.find(".configureData div").each(function(indA, eleA){ colorNSize.tempSizeArray[indA] = [eleA.title,[],[],[],[]] $(eleZ).find("a").each(function(indB, eleB){ colorNSize.tempSizeArray[indA][indB+1] = eleC.title }) }) }, I expect the end array should look like this. [ ["large", ["yellow", "green", "blue"], ["true", "true", "true"], ["$55", "$55","$55"] ], ["Medium", ["yellow", "green", "blue"], ["true", "true", "true"], ["$55", "$55","$55"] ] ] // and so on....

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  • Inheritance issue with ivar on the iPhone

    - by Buffalo
    I am using the BLIP/MYNetwork library to establish a basic tcp socket connection between the iPhone and my computer. So far, the code builds and runs correctly in simulator but deploying to device yields the following error: error: property 'delegate' attempting to use ivar '_delegate' declared in super class of 'TCPConnection' @interface TCPConnection : TCPEndpoint { @private TCPListener *_server; IPAddress *_address; BOOL _isIncoming, _checkedPeerCert; TCPConnectionStatus _status; TCPReader *_reader; TCPWriter *_writer; NSError *_error; NSTimeInterval _openTimeout; } /** The delegate object that will be called when the connection opens, closes or receives messages. */ @property (assign) id<TCPConnectionDelegate> delegate; /** The delegate messages sent by TCPConnection. All methods are optional. */ @protocol TCPConnectionDelegate <NSObject> @optional /** Called after the connection successfully opens. */ - (void) connectionDidOpen: (TCPConnection*)connection; /** Called after the connection fails to open due to an error. */ - (void) connection: (TCPConnection*)connection failedToOpen: (NSError*)error; /** Called when the identity of the peer is known, if using an SSL connection and the SSL settings say to check the peer's certificate. This happens, if at all, after the -connectionDidOpen: call. */ - (BOOL) connection: (TCPConnection*)connection authorizeSSLPeer: (SecCertificateRef)peerCert; /** Called after the connection closes. You can check the connection's error property to see if it was normal or abnormal. */ - (void) connectionDidClose: (TCPConnection*)connection; @end @interface TCPEndpoint : NSObject { NSMutableDictionary *_sslProperties; id _delegate; } - (void) tellDelegate: (SEL)selector withObject: (id)param; @end Does anyone know how I would fix this? Would I simply declare _delegate as a public property of the base class "TCPEndPoint"? Thanks for the help ya'll!

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  • Android SDK: hello world does not run

    - by Alex
    I have installed Java x64, Eclipse Classic Judo x64 + ADT Pluggin. OS win 7 x64. I did installation everything according to the manual. Then created first application and launched it. Emulator was launched but hello world was not. I have not idea what doing wrong. Do anyone knows of such error and my problem as a whole? thx Console log: [2012-10-06 13:35:42 - test] ------------------------------ [2012-10-06 13:35:42 - test] Android Launch! [2012-10-06 13:35:42 - test] adb is running normally. [2012-10-06 13:35:42 - test] Performing com.example.test.MainActivity activity launch [2012-10-06 13:35:42 - test] Automatic Target Mode: launching new emulator with compatible AVD 'AVD_41' [2012-10-06 13:35:42 - test] Launching a new emulator with Virtual Device 'AVD_41' [2012-10-06 13:35:42 - Emulator] Failed to create Context 0x3005 [2012-10-06 13:35:42 - Emulator] emulator: WARNING: Could not initialize OpenglES emulation, using software renderer. [2012-10-06 13:35:42 - Emulator] WARNING: Data partition already in use. Changes will not persist! [2012-10-06 13:35:42 - Emulator] WARNING: SD Card image already in use: C:\Users\Zewisa\.android\avd\AVD_41.avd/sdcard.img [2012-10-06 13:35:42 - Emulator] WARNING: Cache partition already in use. Changes will not persist! [2012-10-06 13:35:42 - Emulator] could not get wglGetExtensionsStringARB [2012-10-06 13:35:42 - Emulator] could not get wglGetExtensionsStringARB [2012-10-06 13:35:42 - Emulator] could not get wglGetExtensionsStringARB [2012-10-06 13:35:42 - Emulator] could not get wglGetExtensionsStringARB [2012-10-06 13:35:42 - Emulator] could not get wglGetExtensionsStringARB [2012-10-06 13:35:42 - Emulator] could not get wglGetExtensionsStringARB [2012-10-06 13:35:42 - Emulator] could not get wglGetExtensionsStringARB [2012-10-06 13:35:42 - Emulator] could not get wglGetExtensionsStringARB [2012-10-06 13:35:42 - Emulator] emulator: warning: opening audio input failed [2012-10-06 13:35:42 - Emulator]

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  • twython search api rate limit: Header information will not be updated

    - by user2715478
    I want to handle the Search-API rate limit of 180 requests / 15 minutes. The first solution I came up with was to check the remaining requests in the header and wait 900 seconds. See the following snippet: results = search_interface.cursor(search_interface.search, q=k, lang=lang, result_type=result_mode) while True: try: tweet = next(results) if limit_reached(search_interface): sleep(900) self.writer(tweet) def limit_reached(search_interface): remaining_rate = int(search_interface.get_lastfunction_header('X-Rate-Limit-Remaining')) return remaining_rate <= 2 But it seems, that the header information are not reseted to 180 after it reached the two remaining requests. The second solution I came up with was to handle the twython exception for rate limitation and wait the remaining amount of time: results = search_interface.cursor(search_interface.search, q=k, lang=lang, result_type=result_mode) while True: try: tweet = next(results) self.writer(tweet) except TwythonError as inst: logger.error(inst.msg) wait_for_reset(search_interface) continue except StopIteration: break def wait_for_reset(search_interface): reset_timestamp = int(search_interface.get_lastfunction_header('X-Rate-Limit-Reset')) now_timestamp = datetime.now().timestamp() seconds_offset = 10 t = reset_timestamp - now_timestamp + seconds_offset logger.info('Waiting {0} seconds for Twitter rate limit reset.'.format(t)) sleep(t) But with this solution I receive this message INFO: Resetting dropped connection: api.twitter.com" and the loop will not continue with the last element of the generator. Have somebody faced the same problems? Regards.

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  • uiview's controls unresponsive.. or how to foul up a view hierarchy

    - by user293139
    Hello all, I'm working on an app that has two sections, a config section and a results section. My config section needs to be 2 separate views (horizontal and vert, and yes, I can hear the intake of breath from here), with one rotatable view for the results. b/c of layout restraints and a lot of pain around rotation, I'm not using a navigation controller. I've been experiencing the joys of rotation experimentation and have settled upon keeping my views contained as subviews of my view controller. i.e. view controller.view.subviews = configH, configV, and results. I then use the controller.view bringSubviewToFront to bring the either the configH, configV, or the result view to the front. Rotation works-queue(humor intended) the angelic choirs... almost. What's happening is that my configV button's are responsive, but when the device (or simulator) is rotated, my configH controls are not. (configV is the second subview added, but the first one to be brought to the front because app comes up in portrait mode) The controls on the results view also work. Plan B was to assign the controller.view to configH, configV, or results. All of my controls now work, but rotation is now fouled up. Question 1: Is there a better way to do this? (a horizontal and vertical config view and a rotatable results view) Question 2: Does the above suggest a design issue, or is it more likely that my addled brain is just missing something in my own code. (nothing from the peanut gallery please) many thanks!

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  • Java many to many association map

    - by Raphael Jolivet
    Hi, I have to classes, ClassA and ClassB and a "many to many" AssociationClass. I want to use a structure to hold the associations between A and B such as I can know, for each instance of A or B, which are their counterparts. I thought of using a Hashmap, with pair keys: Hasmap<Pair<ClassA, ClassB>, AssociationClass> associations; This way, I can add and remove an association between two instances of ClassA and ClassB, and I can query a relation for two given instances. However, I miss the feature of getting all associations defined for a given instance of ClassA or ClassB. I could do it by brute force and loop over all keys of the map to search for associations between a given instance, but this is inefficient and not elegant. Do you know of any data structure / free library that enables this ? I don't want to reinvent the wheel. Thanks in advance for your help, Raphael NB: This is not a "database" question. These objects are pure POJO used for live computation, I don't need persistence stuff.

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  • Trying to convert existing production database table columns from enum to VARCHAR (Rails)

    - by dchua
    Hi everyone, I have a problem that needs me to convert my existing live production (I've duplicated the schema on my local development box, don't worry :)) table column types from enums to a string. Background: Basically, a previous developer left my codebase in absolute shit, migration versions are extremely out of date, and apparently he never used it after a certain point of time in development and now that I'm tasked with migrating a rails 1.2.6 app to 2.3.5, I can't get the tests to run properly on 2.3.5 because my table columns have ENUM column types and they convert to :string, :limit = 0 on my schema.rb which creates the problem of an invalid default value when doing a rake db:test:prepare, like in the case of: Mysql::Error: Invalid default value for 'own_vehicle': CREATE TABLE `lifestyles` (`id` int(11) DEFAULT NULL auto_increment PRIMARY KEY, `member_id` int(11) DEFAULT 0 NOT NULL, `own_vehicle` varchar(0) DEFAULT 'Y' NOT NULL, `hobbies` text, `sports` text, `AStar_activities` text, `how_know_IRC` varchar(100), `IRC_referral` varchar(200), `IRC_others` varchar(100), `IRC_rdrive` varchar(30)) ENGINE=InnoDB I'm thinking of writing a migration task that looks through all the database tables for columns with enum and replace it with VARCHAR and I'm wondering if this is the right way to approach this problem. I'm also not very sure how to write it such that it would loop through my database tables and replace all ENUM colum_types with a VARCHAR. References [1] https://rails.lighthouseapp.com/projects/8994/tickets/997-dbschemadump-saves-enum-columns-as-varchar0-on-mysql [2] http://dev.rubyonrails.org/ticket/2832

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  • Does complex JOINs causes high coupling and maintenance problems ?

    - by ashkan.kh.nazary
    Our project has ~40 tables with complex relations.A colleague believes in using long join queries which enforces me to learn about tables outside of my module but I think I should not concern about tables not directly related to my module and use data access functions (written by those responsible for other modules) when I need data from them. Let me clarify: I am responsible for the ContactVendor module which enables the customers to contact the vendor and start a conversation about some specific product. Products module has it's own complex tables and relations with functions that encapsulate details (for example i18n, activation, product availability etc ...). Now I need to show the product title of some product related to some conversation between the vendor and customers. I may either write a long query that retrieves the product info along with conversation stuff in one shot (which enforces me to learn about Product tables) OR I may pass the relevant product_id to the get_product_info(int) function. First approach is obviously demanding and introduces many bad practices and things I normally consider fault in programming. The problem with the second approach seems to be the countless mini queries these access functions cause and performance loss is a concern when a loop tries to fetch product titles for 100 products using functions that each perform a separate query. So I'm stuck between "don't code to the implementation, code to interface" and performance. What is the right way of doing things ? UPDATE: I'm specially concerned about possible future modifications to those tables outside of my module. What if the Products module decided to change the way they are doing things? or for some reason modify the schema? It means some other modules would break or malfunction until the change is integrated to them. The usual ripple effect problem.

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  • Problem in accessing Windows shared folder on Ubuntu using terminal

    - by vikramtheone
    Hi Guys, Description I have 2 systems with me, one running on Windows(Host) and one on Ubuntu, both on a LAN. On the Windows(Host) I develop software intended for the Linux system and because the Linux system has little external memory, my idea to overcome this is by making the project folder on the Host side a Shared Folder with full access and access it on Ubuntu over the network. To achieve this, I have installed Samba on Ubuntu, when I go to Places -> Network I can see the shared project folder and I simply mount it. A link appears on the desktop. Next, using Nautilus I open the link and I can access the contents of the shared folder. Problem Even though I mount the shared project folder, I don't see it appearing in the /media or the /mnt folder, as a result of this I don't know what path to use to access this folder, from the terminal. For example: When, I mounted my USB stick, as expected, a link for the device appears on the Desktop and I also see a folder in the media folder. So, similarly, a mounted shared folder should have appeared on the /mnt folder, too. Can anyone suggest what I should do now? There are many posts around, but no solid solution for this problem. Help!!! :) Vikram

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  • How can I display multiple django modelformset forms together?

    - by JT
    I have a problem with needing to provide multiple model backed forms on the same page. I understand how to do this with single forms, i.e. just create both the forms call them something different then use the appropriate names in the template. Now how exactly do you expand that solution to work with modelformsets? The wrinkle, of course, is that each 'form' must be rendered together in the appropriate fieldset. For example I want my template to produce something like this: <fieldset> <label for="id_base-0-desc">Home Base Description:</label> <input id="id_base-0-desc" type="text" name="base-0-desc" maxlength="100" /> <label for="id_likes-0-icecream">Want ice cream?</label> <input type="checkbox" name="likes-0-icecream" id="id_likes-0-icecream" /> </fieldset> <fieldset> <label for="id_base-1-desc">Home Base Description:</label> <input id="id_base-1-desc" type="text" name="base-1-desc" maxlength="100" /> <label for="id_likes-1-icecream">Want ice cream?</label> <input type="checkbox" name="likes-1-icecream" id="id_likes-1-icecream" /> </fieldset> I am using a loop like this to process the results for base_form, likes_form in map(None, base_forms, likes_forms): which works as I'd expect (I'm using map because the # of forms can be different). The problem is that I can't figure out a way to do the same thing with the templating engine. The system does work if I layout all the base models together then all the likes models after wards, but it doesn't meet the layout requirements.

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  • Python: Catching / blocking SIGINT during system call

    - by danben
    I've written a web crawler that I'd like to be able to stop via the keyboard. I don't want the program to die when I interrupt it; it needs to flush its data to disk first. I also don't want to catch KeyboardInterruptedException, because the persistent data could be in an inconsistent state. My current solution is to define a signal handler that catches SIGINT and sets a flag; each iteration of the main loop checks this flag before processing the next url. However, I've found that if the system happens to be executing socket.recv() when I send the interrupt, I get this: ^C Interrupted; stopping... // indicates my interrupt handler ran Traceback (most recent call last): File "crawler_test.py", line 154, in <module> main() ... File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/socket.py", line 397, in readline data = recv(1) socket.error: [Errno 4] Interrupted system call and the process exits completely. Why does this happen? Is there a way I can prevent the interrupt from affecting the system call?

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  • What is the Proper approach for Constructing a PhysicalAddress object from Byte Array

    - by Paul Farry
    I'm trying to understand what the correct approach for a constructor that accepts a Byte Array with regard to how it stores it's data (specifically with PhysicalAddress) I have an array of 6 bytes (theAddress) that is constructed once. I have a source array of 18bytes (theAddresses) that is loaded from a TCP Connection. I then copy the 6bytes from theAddress+offset into theAddress and construct the PhysicalAddress from it. Problem is that the PhysicalAddress just stores the Reference to the array that was passed in. Therefore if you subsequently check the addresses they only ever point to the last address that was copied in. When I took a look inside the PhysicalAddress with reflector it's easy to see what's going on. public PhysicalAddress(byte[] address) { this.changed = true; this.address = address; } Now I know this can be solved by creating theAddress array on each pass, but I wanted to find out what really is the best practice for this. Should the constructor of an object that accepts a byte array create it's own private Variable for holding the data and copy it from the original Should it just hold the reference to what was passed in. Should I just created theAddress on each pass in the loop

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  • Serial: write() throttling?

    - by damian
    Hi everyone, I'm working on a project sending serial data to control animation of LED lights, which need to stay in sync with a sound engine. There seems to be a large serial write buffer (OSX (POSIX) + FTDI chipset usb serial device), so without manually restricting the transmission rate, the animation system can get several seconds ahead of the serial transmission. Currently I'm manually restricting the serial write speed to the baudrate (8N1 = 10 bytes serial frame per 8 bytes data, 19200 bps serial - 1920 bytes per second max), but I am having a problem with the sound drifting out of sync over time - it starts fine, but after 10 minutes there's a noticeable (100ms+) lag between the sound and the lights. This is the code that's restricting the serial write speed (called once per animation frame, 'elapsed' is the duration of the current frame, 'baudrate' is the bps (19200)): void BufferedSerial::update( float elapsed ) { baud_timer += elapsed; if ( bytes_written > 1024 ) { // maintain baudrate float time_should_have_taken = (float(bytes_written)*10)/float(baudrate); float time_actually_took = baud_timer; // sleep if we have > 20ms lag between serial transmit and our write calls if ( time_should_have_taken-time_actually_took > 0.02f ) { float sleep_time = time_should_have_taken - time_actually_took; int sleep_time_us = sleep_time*1000.0f*1000.0f; //printf("BufferedSerial::update sleeping %i ms\n", sleep_time_us/1000 ); delayUs( sleep_time_us ); // subtract 128 bytes bytes_written -= 128; // subtract the time it should have taken to write 128 bytes baud_timer -= (float(128)*10)/float(baudrate); } } } Clearly there's something wrong, somewhere. A much better approach would be to be able to determine the number of bytes currently in the transmit queue, and try and keep that below a fixed threshold. Any advice appreciated.

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  • Lazy Sequences that "Look Ahead" for Project Euler Problem 14

    - by ivar
    I'm trying to solve Project Euler Problem 14 in a lazy way. Unfortunately, I may be trying to do the impossible: create a lazy sequence that is both lazy, yet also somehow 'looks ahead' for values it hasn't computed yet. The non-lazy version I wrote to test correctness was: (defn chain-length [num] (loop [len 1 n num] (cond (= n 1) len (odd? n) (recur (inc len) (+ 1 (* 3 n))) true (recur (inc len) (/ n 2))))) Which works, but is really slow. Of course I could memoize that: (def memoized-chain (memoize (fn [n] (cond (= n 1) 1 (odd? n) (+ 1 (memoized-chain (+ 1 (* 3 n)))) true (+ 1 (memoized-chain (/ n 2))))))) However, what I really wanted to do was scratch my itch for understanding the limits of lazy sequences, and write a function like this: (def lazy-chain (letfn [(chain [n] (lazy-seq (cons (if (odd? n) (+ 1 (nth lazy-chain (dec (+ 1 (* 3 n))))) (+ 1 (nth lazy-chain (dec (/ n 2))))) (chain (+ n 1)))))] (chain 1))) Pulling elements from this will cause a stack overflow for n2, which is understandable if you think about why it needs to look 'into the future' at n=3 to know the value of the tenth element in the lazy list because (+ 1 (* 3 n)) = 10. Since lazy lists have much less overhead than memoization, I would like to know if this kind of thing is possible somehow via even more delayed evaluation or queuing?

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  • animated swap position of two buttons

    - by Jagat
    I am trying to swap the position of two buttons. my swapping code looks as below. private void exchangeButtons(Button btn1, Button btn2) { // Create the animation set AnimationSet exchangeAnimation = new AnimationSet(true); TranslateAnimation translate = new TranslateAnimation( Animation.RELATIVE_TO_SELF, btn2.getLeft(), Animation.RELATIVE_TO_SELF, btn1.getLeft(), Animation.RELATIVE_TO_SELF, btn2.getRight(), Animation.RELATIVE_TO_SELF, btn1.getRight() ); translate.setDuration(500); exchangeAnimation.addAnimation(translate); // int fromX = btn1.getLeft(); // int fromY = btn1.getRight(); // int toX = btn2.getLeft(); // int toY = btn2.getRight(); Log.d("ArrangeMe", "view1 pos:" + btn1.getLeft() + ", " +btn1.getRight() + "view2 pos:" + btn2.getLeft() + ", " + btn2.getRight()); AnimationSet exchangeAnimation1 = new AnimationSet(true); TranslateAnimation translate1 = new TranslateAnimation( Animation.RELATIVE_TO_SELF, btn1.getLeft(), Animation.RELATIVE_TO_SELF, btn2.getLeft(), Animation.RELATIVE_TO_SELF, btn1.getRight(), Animation.RELATIVE_TO_SELF, btn2.getRight() ); translate1.setDuration(500); exchangeAnimation1.addAnimation(translate1); // EXECUTE btn1.startAnimation(exchangeAnimation); btn2.startAnimation(exchangeAnimation1); } I call the code as below exchangeButtons(button1, button2); my layout looks as below what happens when i execute the code is, instead of the buttons exchanging their positions, they just disappear for sometime[may be 500 ms] and reappear as they were originally. how to resolve this problem ? will it work properly in device ? regards

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  • Java application design question

    - by ring bearer
    I have a hobby project, which is basically to maintain 'todo' tasks in the way I like. One task can be described as: public class TodoItem { private String subject; private Date dueBy; private Date startBy; private Priority priority; private String category; private Status status; private String notes; } As you can imagine I would have 1000s of todo items at a given time. What is the best strategy to store a todo item? (currently on an XML file) such that all the items are loaded quickly up on app start up(the application shows kind of a dashboard of all the items at start up)? What is the best way to design its back-end so that it can be ported to Android/or a J2ME based phone? Currently this is done using Java Swing. What should I concentrate on so that it works efficiently on a device where memory is limited? The application throws open a form to enter new todo task. For now, I would like to save the newly added task to my-todos.xml once the user presses "save" button. What are the common ways to append such a change to an existing XML file?(note that I don't want to read the whole file again and then persist)

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  • How to embed XBase expressions in an Xtext DSL

    - by Marcus Mathioudakis
    I am writing a simple little DSL for specifying constraints on messages, and Have been trying without success for a while to embed XBase expressions into the language. The Grammar looks like this: grammar org.xtext.businessrules.BusinessRules with org.eclipse.xtext.xbase.Xbase //import "http://www.eclipse.org/xtext/xbase/Xbase" as xbase import "http://www.eclipse.org/xtext/common/JavaVMTypes" as jvmTypes generate businessRules "http://www.xtext.org/businessrules/BusinessRules" Start: rules+=Constraint*; Constraint: {Constraint} 'FOR' 'PAYLOAD' payload=PAYLOAD 'ELEMENT' element=ID 'CONSTRAINED BY' constraint=XExpression; PAYLOAD: "SimulationSessionEvents" |"stacons" |"any" ; Range: 'above' min=INT ('below' max=INT)? |'below' max=INT ('above' min=INT)? ; When trying to parse a file such as: FOR PAYLOAD SimulationSessionEvents ELEMENT matrix CONSTRAINED BY ... I can't get it to work for ... = any kind of Arithmetic expression, although it works for ...= loop or if expression, or even just a number. As soon as I do something like '-5' or '4-5' it says Couldn't resolve reference to JvmIdentifiableElement '-', even though the Xbase.xtext Grammar looks like it allows these expressions. I don't think I'm missing any Jars, as it doesn't complain when I run the mwe workflow, but only when trying to parse the input file. Any help would be much appreciated.

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  • iphone crash log with dSym not loading debug information

    - by AngeDeLaMort
    Hello, I was trying to see why my application crashed on the device (iPhone) using the dSym generated along the executable (in ad hoc), but I don't know why, there isn't any useful information. It seems that "Organizer" is able to find the appropriate dSym and translate some data into more readable one, but when it comes to my application, I just have an address. Since I know how to reproduce it, I've tried to setup my build so it can help me in the future. So, I've tried to find if I had all the proper flags set int the project build properties and everything seems fine. So after doing some research, it seems that all information are stripped during link time and the dSym seems completely useless. I've played with some flags, but nothing changed. So, is there something special to do in order to get the crash file human readable? Or is it impossible in the ad hoc setting? The closest thing near to work that I've done was to build a debug version and look up the address in it. At least it seems to give the right file. So, I made a sample app and here what I have: (the line I want is #4): Thread 0 Crashed: 0 libobjc.A.dylib 0x00003ebc objc_msgSend + 20 1 UIKit 0x0005c970 -[UIView dealloc] + 60 2 UIKit 0x0005c840 -[UIImageView dealloc] + 76 3 CoreFoundation 0x0003963a -[NSObject release] + 28 4 MyApplication 0x000046a6 0x1000 + 13990 5 UIKit 0x00069750 -[UIViewController view] + 44 6 MyApplication 0x000053fa 0x1000 + 17402 The crash is made using 2 successive releases on an object. Thanks in advance.

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  • XSLT-Looping and recursion based on parameter passed

    - by contactkx
    I have an XML organized like below- <section name="Parent 1 Text here" ID="1" > <section name="Child 1 Text here" ID="11"> </section> <section name="Child 2 Text here" ID="12"> <section name="GrandChild Text here" ID="121" > </section> </section> </section> <section name="Parent 2 Text here" ID="2" > <section name="Child 1 Text here" ID="22"> </section> <section name="Child 2 Text here" ID="23"> <section name="GrandChild Text here" ID="232" > </section> </section> </section> I have to produce the below output XML - <section name="Parent 1 Text here" ID="1" > <section name="Child 2 Text here" ID="12"> <section name="GrandChild Text here" ID="121" > </section> </section> </section> <section name="Parent 2 Text here" ID="2" > <section name="Child 2 Text here" ID="23"> </section> </section> I have to achive above using XSLT 1.0 transformation. I was planning to pass a comma separated string as a parameter with value= "1,12,121,2,23" My question- How to loop the comma separated parameter in XSLT 1.0 ? Is there a simpler way to achieve the above. Please remember I have to do this in XSLT 1.0 Your help is appreciated.

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  • why DataColumn AllowDbNull is true even if oracle db does not allow null

    - by matti
    Hi. I have column SomeId in table SomeLink. When I look with tOra or Sql Plus Worksheet both state: tOra: Column name Data type Default Null Comment SOMEID INTEGER {null} NOT NULL {null} Sql Plus: SOMEID NOT NULL NUMBER(38) I have authored a method that's intended to give default values to all NOT NULL fields that don't have values: public static void GetDefaultValuesForNonNullColumns(DataRow row) { foreach(DataColumn col in row.Table.Columns) { if (Convert.IsDBNull(row[col]) && !col.AllowDBNull) { if (ColumnIsNumeric(col.DataType)) row[col] = 0; else if (col.DataType == typeof(DateTime)) row[col] = DateTime.Now; else if (col.DataType == typeof(String)) row[col] = string.Empty; else if (col.DataType == typeof(Char)) row[col] = ' '; else throw new Exception(string.Format("Unsupported column type: {0}", col.DataType)); } } } When SOMEID is handled in loop the AllowDBNull = true. I really can't understand. The table is created in DataSet like this: _someLinkAdptr = _dbFactory.CreateDataAdapter(); _someLinkAdptr.SelectCommand = _dbFactory.CreateCommand(); _someLinkAdptr.SelectCommand.Connection = _cnctn; _someLinkAdptr.SelectCommand.CommandText = GetSomeLinkSelectTxtAndParams(_someLinkAdptr.SelectCommand, UndefinedValue.ToString(), UndefinedValue.ToString()); Select command returns no rows. The idea is that I can then use commandbuilder to get InsertCommand without building it myself. The row is added to dataset's table like this: private static void CreateDocLink(int anId, int anotherId) { DataRow row = _someDataSet.Tables["SomeLink"].NewRow(); row["AnId"] = anId; row["AnotherId"] = anotherId; Utility.GetDefaultValuesForNonNullColumns(row); _someDataSet.Tables["SomeLink"].Rows.Add(row); } When DataAdapter is updated to oracle db I get: ORA-01400: cannot insert NULL into (SOMESCHEMA.SOMELINK.SOMEID) Cheers & BR -Matti

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