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  • Jquery DateJs, is there validation for full date?

    - by Cesar Lopez
    Hi all, I just find out about the power of date js, And its great!!! As I am a newbie I was wondering if there is any kind of general validitation for different types of full dates. eg. var d1 = Date.parse('2000-10-18, 10:06 AM'); alert(d1.toString('HH:mm')); If date is ('200-10-18, 10:06 AM'), of course it doesn't like it. So my question is if there is any quick way to validate the full date, rather than having to validate one by one. Thanks.

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  • Optimize date query for large child tables: GiST or GIN?

    - by Dave Jarvis
    Problem 72 child tables, each having a year index and a station index, are defined as follows: CREATE TABLE climate.measurement_12_013 ( -- Inherited from table climate.measurement_12_013: id bigint NOT NULL DEFAULT nextval('climate.measurement_id_seq'::regclass), -- Inherited from table climate.measurement_12_013: station_id integer NOT NULL, -- Inherited from table climate.measurement_12_013: taken date NOT NULL, -- Inherited from table climate.measurement_12_013: amount numeric(8,2) NOT NULL, -- Inherited from table climate.measurement_12_013: category_id smallint NOT NULL, -- Inherited from table climate.measurement_12_013: flag character varying(1) NOT NULL DEFAULT ' '::character varying, CONSTRAINT measurement_12_013_category_id_check CHECK (category_id = 7), CONSTRAINT measurement_12_013_taken_check CHECK (date_part('month'::text, taken)::integer = 12) ) INHERITS (climate.measurement) CREATE INDEX measurement_12_013_s_idx ON climate.measurement_12_013 USING btree (station_id); CREATE INDEX measurement_12_013_y_idx ON climate.measurement_12_013 USING btree (date_part('year'::text, taken)); (Foreign key constraints to be added later.) The following query runs abysmally slow due to a full table scan: SELECT count(1) AS measurements, avg(m.amount) AS amount FROM climate.measurement m WHERE m.station_id IN ( SELECT s.id FROM climate.station s, climate.city c WHERE -- For one city ... -- c.id = 5182 AND -- Where stations are within an elevation range ... -- s.elevation BETWEEN 0 AND 3000 AND 6371.009 * SQRT( POW(RADIANS(c.latitude_decimal - s.latitude_decimal), 2) + (COS(RADIANS(c.latitude_decimal + s.latitude_decimal) / 2) * POW(RADIANS(c.longitude_decimal - s.longitude_decimal), 2)) ) <= 50 ) AND -- -- Begin extracting the data from the database. -- -- The data before 1900 is shaky; insufficient after 2009. -- extract( YEAR FROM m.taken ) BETWEEN 1900 AND 2009 AND -- Whittled down by category ... -- m.category_id = 1 AND m.taken BETWEEN -- Start date. (extract( YEAR FROM m.taken )||'-01-01')::date AND -- End date. Calculated by checking to see if the end date wraps -- into the next year. If it does, then add 1 to the current year. -- (cast(extract( YEAR FROM m.taken ) + greatest( -1 * sign( (extract( YEAR FROM m.taken )||'-12-31')::date - (extract( YEAR FROM m.taken )||'-01-01')::date ), 0 ) AS text)||'-12-31')::date GROUP BY extract( YEAR FROM m.taken ) The sluggishness comes from this part of the query: m.taken BETWEEN /* Start date. */ (extract( YEAR FROM m.taken )||'-01-01')::date AND /* End date. Calculated by checking to see if the end date wraps into the next year. If it does, then add 1 to the current year. */ (cast(extract( YEAR FROM m.taken ) + greatest( -1 * sign( (extract( YEAR FROM m.taken )||'-12-31')::date - (extract( YEAR FROM m.taken )||'-01-01')::date ), 0 ) AS text)||'-12-31')::date The HashAggregate from the plan shows a cost of 10006220141.11, which is, I suspect, on the astronomically huge side. There is a full table scan on the measurement table (itself having neither data nor indexes) being performed. The table aggregates 237 million rows from its child tables. Question What is the proper way to index the dates to avoid full table scans? Options I have considered: GIN GiST Rewrite the WHERE clause Separate year_taken, month_taken, and day_taken columns to the tables What are your thoughts? Thank you!

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  • a4j:commandButton causes full page reload on IE7

    - by Greg Charles
    Our process allows users to activate their account, and then configure e-mail preferences. We're using the tag: <a4j:commandButton id="activate" action="#{controller.agreeAction}" image="/img/ok.png" styleClass="activate-button" reRender="mainContent, sideBar" oncomplete="showEmailDialog();" /> This works fine on Firefox, but on IE, the showEmaiDialog() fires off to display the new dialog, and then the full page reloads, which instantly hides it again. I put in numerous alert() calls to make sure of what was happening. I see the e-mail dialog until I clear the final alert box in in the showEmailDialog() script, and then I see the alerts that I put into jQuery(document).ready(). Why does IE do a full page reload instead of just refreshing the requested sections?

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  • How can I make Ruby rake display the full backtrace on uncaught exception

    - by Martinos
    As you may know rake swallows the full backtrace on uncaught exception. If I want to have a full backtrace, I need to add the --trace option. I find this very annoying because some of my tasks take long time to run (up to 6 hours), when it crashes I don't have any debugging info. I need to run it again with the --trace. On top of that, the system may not be in the same state as when the error occurred, so it may not show afterward. I always have to add --trace on any tasks. This displasy stuff that I don't want to see when the task is executed. Is there a way to change this default behaviour? (which I don't think is useful at all)

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  • CSS/HTML: Highlighting the "full width avaialble" to a list item

    - by JoshuaD
    I'm working on a website for a small law office. In the side-menu, I'm trying to highlight the "current page". I have tried changing the background of the LI, but this doesn't quite do the trick; the list item doesn't spread to the full width of the menu, so it looks bad. Here's a jfiddle. I would like the yellow section to highlight like the pink section is highlighted: filling up the full vertical and horizontal space, not just highlighting the text. Any suggestions on how to do this? I've included the style tag in the html just for example, obviously, and my real solution will be a little different when it's done. But I can't move forward until I figure out how to somehow highlight the entire line.

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  • Search a string to find which records in table are inside said string

    - by Improfane
    Hello, Say I have a string. Then I have a number of unique tokens or keywords, potentially a large number in a database. I want to search and find out which of these database strings are inside the string I provide (and get the IDs of them). Is there a way of using a query to search the provided string or must it be taken to application space? Am I right in thinking that this is not a 'full text search'? Would the best method be to insert it into the database to make it a full text search?

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  • Nhibernate.Bytecode.Castle Trust Level on IIS

    - by jack london
    Trying to deploy the wcf service, depended on nhibernate. And getting the following exception On Reflection activator. [SecurityException: That assembly does not allow partially trusted callers.] System.Security.CodeAccessSecurityEngine.ThrowSecurityException(Assembly asm, PermissionSet granted, PermissionSet refused, RuntimeMethodHandle rmh, SecurityAction action, Object demand, IPermission permThatFailed) +150 System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck) +0 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache) +86 System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) +230 System.Activator.CreateInstance(Type type, Boolean nonPublic) +67 NHibernate.Bytecode.ActivatorObjectsFactory.CreateInstance(Type type) +8 NHibernate.Driver.ReflectionBasedDriver.CreateConnection() +28 NHibernate.Connection.DriverConnectionProvider.GetConnection() +56 NHibernate.Tool.hbm2ddl.SchemaExport.Execute(Action`1 scriptAction, Boolean export, Boolean justDrop) +376 in IIS configuration service's trust level is Full-trust also application's web config's trust level is full. how could i make this service in working state?

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  • Updating div after full page refresh following AJAX request

    - by TonE
    Hi, I have an AJAX controller action which returns JSON. The returned JSON is handled via jQuery and contains a message displayed in an update div. The JSON also contains a flag which indicates a change in state. If this is true the entire page needs to be reloaded from a different url. This is currently performed in the jQuery using window.location.replace(url). In the situation where a full page refresh occurs, I still want to display the message from the JSON in the update div, but after the page has fully reloaded. How can I ensure the div is updated with the message after the window.location.replace call and the page has been completely reloaded? Thanks. (I realise AJAX is not intended for full page refreshes but I can't think of a simple way of avoiding it in this scenario. Normal behaviour here is updating the div with a status message.)

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  • Removing a UIView from its superView and expanding its frame to full screen

    - by Magic Bullet Dave
    I have an object that is a subclass of UIView that can be added to a view hierarchy as a subView. I want to be able to remove the UIView from its superView and add it as a subView of the main window and then expand to full screen. Something along the lines of: // Remove from superView and add to mainWindow [self retain]; [self removeFromSuperView]; [self addSubView:mainWindow]; // Animate to full screen [UIView beginAnimations:@"expandToFullScreen" context:nil]; [UIView setAnimationDuration:1.0]; self.frame = [[UIScreen mainScreen] applicationFrame]; [UIView commitAnimations]; [self release]; Firstly am I on the right lines? Secondly, is there an easily way for the object to get a pointer to the mainWindow? Thanks Dave

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  • How to get only a filename (not full path) into $1, using the PERL, regular expressions

    - by Scott
    I want to keep only the filenames (not full paths) and add the filename to some bbcode. Here is the HTML to be converted: <a href=/path/to/full/image.jpg rel=prettyPhoto><img rel=prettyPhoto src=/path/to/thumb/image.jpg /></a> Notice I cannot have rel="foo" (no double quotes).. Here is what I have in PERL, to perform the conversion: s/\<a href=(.+?)\ rel=prettyPhoto\>\<img rel=prettyPhoto src=(.+?) \/>\<\/a\>/\[box\]$1\[\/box\]/gi; This converts the HTML to: [box]/path/to/image.jpg[/box] But this is what I want as a result: [box]image.jpg[/box] The HTML must remain the same. So how do I change my PERL so that $1 contains only the filename?

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  • facebook api getting full posts with > 2 comments or > 4 likes

    - by ejang
    when I make the user/feed request on the Facebook Open Graph API, I get a feed object where posts with 2 comments or 4 likes don't reveal the detailed information for those specific comments. I am using https://github.com/Thuzi/facebook-node-sdk to make requests but it is very similar to the 'request' NodeJS library. I can get the full posts individually by making a separate request for that post's Open Graph ID, but this doesn't lend itself to fun code because requests are asynchronous and nesting more asynchronous calls within asynchronous calls doesn't lend itself to fun code. Any way I can obtain the full posts?

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  • factory class, wrong number of arguments being passed to subclass constructor

    - by Hugh Bothwell
    I was looking at Python: Exception in the separated module works wrong which uses a multi-purpose GnuLibError class to 'stand in' for a variety of different errors. Each sub-error has its own ID number and error format string. I figured it would be better written as a hierarchy of Exception classes, and set out to do so: class GNULibError(Exception): sub_exceptions = 0 # patched with dict of subclasses once subclasses are created err_num = 0 err_format = None def __new__(cls, *args): print("new {}".format(cls)) # DEBUG if len(args) and args[0] in GNULibError.sub_exceptions: print(" factory -> {} {}".format(GNULibError.sub_exceptions[args[0]], args[1:])) # DEBUG return super(GNULibError, cls).__new__(GNULibError.sub_exceptions[args[0]], *(args[1:])) else: print(" plain {} {}".format(cls, args)) # DEBUG return super(GNULibError, cls).__new__(cls, *args) def __init__(self, *args): cls = type(self) print("init {} {}".format(cls, args)) # DEBUG self.args = args if cls.err_format is None: self.message = str(args) else: self.message = "[GNU Error {}] ".format(cls.err_num) + cls.err_format.format(*args) def __str__(self): return self.message def __repr__(self): return '{}{}'.format(type(self).__name__, self.args) class GNULibError_Directory(GNULibError): err_num = 1 err_format = "destination directory does not exist: {}" class GNULibError_Config(GNULibError): err_num = 2 err_format = "configure file does not exist: {}" class GNULibError_Module(GNULibError): err_num = 3 err_format = "selected module does not exist: {}" class GNULibError_Cache(GNULibError): err_num = 4 err_format = "{} is expected to contain gl_M4_BASE({})" class GNULibError_Sourcebase(GNULibError): err_num = 5 err_format = "missing sourcebase argument: {}" class GNULibError_Docbase(GNULibError): err_num = 6 err_format = "missing docbase argument: {}" class GNULibError_Testbase(GNULibError): err_num = 7 err_format = "missing testsbase argument: {}" class GNULibError_Libname(GNULibError): err_num = 8 err_format = "missing libname argument: {}" # patch master class with subclass reference # (TO DO: auto-detect all available subclasses instead of hardcoding them) GNULibError.sub_exceptions = { 1: GNULibError_Directory, 2: GNULibError_Config, 3: GNULibError_Module, 4: GNULibError_Cache, 5: GNULibError_Sourcebase, 6: GNULibError_Docbase, 7: GNULibError_Testbase, 8: GNULibError_Libname } This starts out with GNULibError as a factory class - if you call it with an error number belonging to a recognized subclass, it returns an object belonging to that subclass, otherwise it returns itself as a default error type. Based on this code, the following should be exactly equivalent (but aren't): e = GNULibError(3, 'missing.lib') f = GNULibError_Module('missing.lib') print e # -> '[GNU Error 3] selected module does not exist: 3' print f # -> '[GNU Error 3] selected module does not exist: missing.lib' I added some strategic print statements, and the error seems to be in GNULibError.__new__: >>> e = GNULibError(3, 'missing.lib') new <class '__main__.GNULibError'> factory -> <class '__main__.GNULibError_Module'> ('missing.lib',) # good... init <class '__main__.GNULibError_Module'> (3, 'missing.lib') # NO! ^ why? I call the subclass constructor as subclass.__new__(*args[1:]) - this should drop the 3, the subclass type ID - and yet its __init__ is still getting the 3 anyway! How can I trim the argument list that gets passed to subclass.__init__?

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  • Creating a popup tool bar in a full screen NSOpenGLView (OSX Cocoa)

    - by Mike2012
    I have a Cocoa app in which one of my NSOpenGLViews can go into full screen mode (I do this with the method enterFullScreenMode:withOptions:). I would like to create a little widget that when you mouse over it, a toolbar pops up with some different controls. I am wondering what would be the best way to implement this widget? At first I thought about using a panel but I don't think you can bring up any windows when in full screen mode. Also, it seems that you can't add a subview to an NSOpenGLView? Are these two assumptions correct? What else could I use to accomplish this?

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  • Replace url() relative path with full domain in css files

    - by deepwell
    I'd like to run a script on release that replaces all url() declarations in a css file with the full domain path, because images are hosted on a static web server. Example Current: background-image: url(/images/menu.gif); Desired: background-image: url(http://example.com/images/menu.gif); Current: background-image: url('/images/menu.gif'); Desired: background-image: url('http://example.com/images/menu.gif'); Current: background-image: url("/images/menu.gif"); Desired: background-image: url("http://example.com/images/menu.gif"); I have concocted a bash script using sed to do just that, but it does not handle url with quotes url(''), or urls that already have a full path. STATIC_HOST="http://example.com" sed -i '' "s|url(\([^)]*\)|url($STATIC_HOST\1|g" main.css

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  • CFfile -- value is not set to the queried data

    - by user494901
    I have this add user form, it also doubles as a edit user form by querying the data and setting the value="#query.xvalue#". If the user exists (eg, you're editing a user, it loads in the users data from the database. When doing this on the <cffile field it does not load in the data, then when the insert goes to insert data it overrights the database values with a blank string (If a user does not input a new file). How do I avoid this? Code: Form: <br/>Digital Copy<br/> <!--- If null, set a default if not, set the default to database default ---> <cfif len(Trim(certificationsList.cprAdultImage)) EQ 0> <cfinput type="file" required="no" name="cprAdultImage" value="" > <cfelse> File Exists: <cfoutput><a href="#certificationsList.cprAdultImage#">View File</a></cfoutput> <cfinput type="file" required="no" name="cprAdultImage" value="#certificationsList.cprAdultImage#"> </cfif> Form Processor: <!--- Has a file been specificed? ---> <cfif not len(Trim(form.cprAdultImage)) EQ 0> <cffile action="upload" filefield="cprAdultImage" destination="#destination#" nameConflict="makeUnique"> <cfinvokeargument name="cprAdultImage" value="#pathOfFile##cffile.serverFile#"> <cfelse> <cfinvokeargument name="cprAdultImage" value=""> </cfif> CFC ARGS: <cfargument name="cprAdultExp" required="NO"> <cfargument name="cprAdultCompany" type="string" required="no"> <cfargument name="cprAdultImage" type="string" required="no"> <cfargument name="cprAdultOnFile" type="boolean" required="no"> Query: UPDATE mod_StudentCertifications SET cprAdultExp='#DateFormat(ARGUMENTS.cprAdultExp, "mm/dd/yyyy")#', cprAdultCompany='#Trim(ARGUMENTS.cprAdultCompany)#', cprAdultImage='#Trim(ARGUMENTS.cprAdultImage)#', cprAdultOnFile='#Trim(ARGUMENTS.cprAdultOnFile)#' INSERT INTO mod_StudentCertifications( cprAdultExp, cprAdultcompany, cprAdultImage, cprAdultOnFile

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  • vagrant fails to bring up additional adapter for centos vm using virtual box provider

    - by Anadi Misra
    this is in continuation of the question asked here about host only adapter on dhcp I upgraded to vagrant 1.6.3 and the updated Vagrantfile to following setting for multiple adapters # add additional adapter for inter machine networking dev.vm.network :private_network, :type => "dhcp", :adapter => "2", :netmask => "255.255.255.0" it goes through creating adapters but then fails bringing up the mic on vm Anadis-MacBook-Pro:full-stack-env anadi$ vagrant up Bringing machine 'full-stack-env' up with 'virtualbox' provider... ==> full-stack-env: Clearing any previously set forwarded ports... ==> full-stack-env: Clearing any previously set network interfaces... ==> full-stack-env: Preparing network interfaces based on configuration... full-stack-env: Adapter 1: nat full-stack-env: Adapter 2: hostonly ==> full-stack-env: Forwarding ports... full-stack-env: 22 => 4223 (adapter 1) full-stack-env: 8080 => 8090 (adapter 1) ==> full-stack-env: Running 'pre-boot' VM customizations... ==> full-stack-env: Booting VM... ==> full-stack-env: Waiting for machine to boot. This may take a few minutes... full-stack-env: SSH address: 127.0.0.1:4223 full-stack-env: SSH username: vagrant full-stack-env: SSH auth method: private key full-stack-env: Warning: Connection timeout. Retrying... full-stack-env: Warning: Connection timeout. Retrying... full-stack-env: Warning: Remote connection disconnect. Retrying... ==> full-stack-env: Machine booted and ready! ==> full-stack-env: Checking for guest additions in VM... ==> full-stack-env: Setting hostname... ==> full-stack-env: Configuring and enabling network interfaces... The following SSH command responded with a non-zero exit status. Vagrant assumes that this means the command failed! ARPCHECK=no /sbin/ifup eth 2> /dev/null Stdout from the command: Device eth does not seem to be present, delaying initialization. Stderr from the command: how ever when I log in to the environment I see two network interfaces as expected Anadis-MacBook-Pro:full-stack-env anadi$ vagrant ssh Last login: Wed Jun 4 12:54:47 2014 from 10.0.2.2 [vagrant@full-stack-env ~]$ ifconfig eth0 Link encap:Ethernet HWaddr 08:00:27:BD:39:57 inet addr:10.0.2.15 Bcast:10.0.2.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:febd:3957/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:511 errors:0 dropped:0 overruns:0 frame:0 TX packets:360 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:54574 (53.2 KiB) TX bytes:46675 (45.5 KiB) eth1 Link encap:Ethernet HWaddr 08:00:27:A3:86:C9 inet addr:172.28.128.3 Bcast:172.28.128.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:fea3:86c9/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5 errors:0 dropped:0 overruns:0 frame:0 TX packets:9 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1360 (1.3 KiB) TX bytes:894 (894.0 b) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) I am bit confused here on why it is trying to add another mic (eth2)? In the VM I used for creating this vagrant box, I had added two NICs already.

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  • Why doesn't my environment variable get set?

    - by reprogrammer
    I have to set an environment variable called GDK_NATIVE_WINDOWS to fix the problem with Eclipse buttons in Ubuntu. To set the environment variable, I added the following line to ~/.pam_environment. GDK_NATIVE_WINDOWS DEFAULT=true Surprisingly, the environment variable doesn't get set when I echo $GDK_NATIVE_WINDOWS in a terminal. However, all other environment variables that I've listed in ~/.pam_environment are set properly. Besides, when I switch to a tty, e.g. Alt+Ctrl+F1, the environment variable gets set correctly. Can anyone tell what's wrong with setting this environment variable in ~/.pam_environment?

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  • Why doesn't my environment variable get set?

    - by reprogrammer
    I have to set an environment variable called GDK_NATIVE_WINDOWS to fix the problem with Eclipse buttons in Ubuntu. To set the environment variable, I added the following line to ~/.pam_environment. GDK_NATIVE_WINDOWS DEFAULT=true Surprisingly, the environment variable doesn't get set when I echo $GDK_NATIVE_WINDOWS in a terminal. However, all other environment variables that I've listed in ~/.pam_environment are set properly. Besides, when I switch to a tty, e.g. Alt+Ctrl+F1, the environment variable gets set correctly. Can anyone tell what's wrong with setting this environment variable in ~/.pam_environment?

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  • How can I make full-screen desktop applications only cover the snapped desktop?

    - by nhinkle
    In Windows 8, you can "snap" two apps next to each other, and one of those apps can be the legacy Windows desktop environment. A convenient application for this (or so I thought) would be to snap a chat client, small browser, or other app while watching content in full-screen on the desktop. The problem with this is that full screen desktop applications will take over the entire screen, even if the desktop is snapped to only occupy 3/4th of the display. What I would like is some way to force "full screen" desktop apps to only cover the snapped desktop area, and to truly go full screen if the desktop is snapped to full-width. Is there some way to configure this? If that didn't make sense, let me illustrate with pictures: Desktop in snapped view with SU chat in mini-browser: What happens when you click "full screen": What I want to happen when I click "full screen" (note this is digitally altered, not a real screenshot)

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  • Anatomy of a .NET Assembly - Custom attribute encoding

    - by Simon Cooper
    In my previous post, I covered how field, method, and other types of signatures are encoded in a .NET assembly. Custom attribute signatures differ quite a bit from these, which consequently affects attribute specifications in C#. Custom attribute specifications In C#, you can apply a custom attribute to a type or type member, specifying a constructor as well as the values of fields or properties on the attribute type: public class ExampleAttribute : Attribute { public ExampleAttribute(int ctorArg1, string ctorArg2) { ... } public Type ExampleType { get; set; } } [Example(5, "6", ExampleType = typeof(string))] public class C { ... } How does this specification actually get encoded and stored in an assembly? Specification blob values Custom attribute specification signatures use the same building blocks as other types of signatures; the ELEMENT_TYPE structure. However, they significantly differ from other types of signatures, in that the actual parameter values need to be stored along with type information. There are two types of specification arguments in a signature blob; fixed args and named args. Fixed args are the arguments to the attribute type constructor, named arguments are specified after the constructor arguments to provide a value to a field or property on the constructed attribute type (PropertyName = propValue) Values in an attribute blob are limited to one of the basic types (one of the number types, character, or boolean), a reference to a type, an enum (which, in .NET, has to use one of the integer types as a base representation), or arrays of any of those. Enums and the basic types are easy to store in a blob - you simply store the binary representation. Strings are stored starting with a compressed integer indicating the length of the string, followed by the UTF8 characters. Array values start with an integer indicating the number of elements in the array, then the item values concatentated together. Rather than using a coded token, Type values are stored using a string representing the type name and fully qualified assembly name (for example, MyNs.MyType, MyAssembly, Version=1.0.0.0, Culture=neutral, PublicKeyToken=0123456789abcdef). If the type is in the current assembly or mscorlib then just the type name can be used. This is probably done to prevent direct references between assemblies solely because of attribute specification arguments; assemblies can be loaded in the reflection-only context and attribute arguments still processed, without loading the entire assembly. Fixed and named arguments Each entry in the CustomAttribute metadata table contains a reference to the object the attribute is applied to, the attribute constructor, and the specification blob. The number and type of arguments to the constructor (the fixed args) can be worked out by the method signature referenced by the attribute constructor, and so the fixed args can simply be concatenated together in the blob without any extra type information. Named args are different. These specify the value to assign to a field or property once the attribute type has been constructed. In the CLR, fields and properties can be overloaded just on their type; different fields and properties can have the same name. Therefore, to uniquely identify a field or property you need: Whether it's a field or property (indicated using byte values 0x53 and 0x54, respectively) The field or property type The field or property name After the fixed arg values is a 2-byte number specifying the number of named args in the blob. Each named argument has the above information concatenated together, mostly using the basic ELEMENT_TYPE values, in the same way as a method or field signature. A Type argument is represented using the byte 0x50, and an enum argument is represented using the byte 0x55 followed by a string specifying the name and assembly of the enum type. The named argument property information is followed by the argument value, using the same encoding as fixed args. Boxed objects This would be all very well, were it not for object and object[]. Arguments and properties of type object allow a value of any allowed argument type to be specified. As a result, more information needs to be specified in the blob to interpret the argument bytes as the correct type. So, the argument value is simple prepended with the type of the value by specifying the ELEMENT_TYPE or name of the enum the value represents. For named arguments, a field or property of type object is represented using the byte 0x51, with the actual type specified in the argument value. Some examples... All property signatures start with the 2-byte value 0x0001. Similar to my previous post in the series, names in capitals correspond to a particular byte value in the ELEMENT_TYPE structure. For strings, I'll simply give the string value, rather than the length and UTF8 encoding in the actual blob. I'll be using the following enum and attribute types to demonstrate specification encodings: class AttrAttribute : Attribute { public AttrAttribute() {} public AttrAttribute(Type[] tArray) {} public AttrAttribute(object o) {} public AttrAttribute(MyEnum e) {} public AttrAttribute(ushort x, int y) {} public AttrAttribute(string str, Type type1, Type type2) {} public int Prop1 { get; set; } public object Prop2 { get; set; } public object[] ObjectArray; } enum MyEnum : int { Val1 = 1, Val2 = 2 } Now, some examples: Here, the the specification binds to the (ushort, int) attribute constructor, with fixed args only. The specification blob starts off with a prolog, followed by the two constructor arguments, then the number of named arguments (zero): [Attr(42, 84)] 0x0001 0x002a 0x00000054 0x0000 An example of string and type encoding: [Attr("MyString", typeof(Array), typeof(System.Windows.Forms.Form))] 0x0001 "MyString" "System.Array" "System.Windows.Forms.Form, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" 0x0000 As you can see, the full assembly specification of a type is only needed if the type isn't in the current assembly or mscorlib. Note, however, that the C# compiler currently chooses to fully-qualify mscorlib types anyway. An object argument (this binds to the object attribute constructor), and two named arguments (a null string is represented by 0xff and the empty string by 0x00) [Attr((ushort)40, Prop1 = 12, Prop2 = "")] 0x0001 U2 0x0028 0x0002 0x54 I4 "Prop1" 0x0000000c 0x54 0x51 "Prop2" STRING 0x00 Right, more complicated now. A type array as a fixed argument: [Attr(new[] { typeof(string), typeof(object) })] 0x0001 0x00000002 // the number of elements "System.String" "System.Object" 0x0000 An enum value, which is simply represented using the underlying value. The CLR works out that it's an enum using information in the attribute constructor signature: [Attr(MyEnum.Val1)] 0x0001 0x00000001 0x0000 And finally, a null array, and an object array as a named argument: [Attr((Type[])null, ObjectArray = new object[] { (byte)2, typeof(decimal), null, MyEnum.Val2 })] 0x0001 0xffffffff 0x0001 0x53 SZARRAY 0x51 "ObjectArray" 0x00000004 U1 0x02 0x50 "System.Decimal" STRING 0xff 0x55 "MyEnum" 0x00000002 As you'll notice, a null object is encoded as a null string value, and a null array is represented using a length of -1 (0xffffffff). How does this affect C#? So, we can now explain why the limits on attribute arguments are so strict in C#. Attribute specification blobs are limited to basic numbers, enums, types, and arrays. As you can see, this is because the raw CLR encoding can only accommodate those types. Special byte patterns have to be used to indicate object, string, Type, or enum values in named arguments; you can't specify an arbitary object type, as there isn't a generalised way of encoding the resulting value in the specification blob. In particular, decimal values can't be encoded, as it isn't a 'built-in' CLR type that has a native representation (you'll notice that decimal constants in C# programs are compiled as several integer arguments to DecimalConstantAttribute). Jagged arrays also aren't natively supported, although you can get around it by using an array as a value to an object argument: [Attr(new object[] { new object[] { new Type[] { typeof(string) } }, 42 })] Finally... Phew! That was a bit longer than I thought it would be. Custom attribute encodings are complicated! Hopefully this series has been an informative look at what exactly goes on inside a .NET assembly. In the next blog posts, I'll be carrying on with the 'Inside Red Gate' series.

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  • SQL Server 2008 ContainsTable, CTE, and Paging

    - by David Murdoch
    I'd like to perform efficient paging using containstable. The following query selects the top 10 ranked results from my database using containstable when searching for a name (first or last) that begins with "Joh". DECLARE @Limit int; SET @Limit = 10; SELECT TOP @Limit c.ChildID, c.PersonID, c.DOB, c.Gender FROM [Person].[vFullName] AS v INNER JOIN CONTAINSTABLE( [Person].[vFullName], (FullName), IS ABOUT ( "Joh*" WEIGHT (.4), "Joh" WEIGHT (.6)) ) AS k3 ON v.PersonID = k3.[KEY] JOIN [Child].[Details] c ON c.PersonID = v.PersonID JOIN [Person].[Details] p ON p.PersonID = c.PersonID ORDER BY k3.RANK DESC, FullName ASC, p.Active DESC, c.ChildID ASC I'd like to combine it with the following CTE which returns the 10th-20th results ordered by ChildID (the primary key): DECLARE @Start int; DECLARE @Limit int; SET @Start = 10; SET @Limit = 10; WITH ChildEntities AS ( SELECT ROW_NUMBER() OVER (ORDER BY ChildID) AS Row, ChildID FROM Child.Details ) SELECT c.ChildID, c.PersonID, c.DOB, c.Gender FROM ChildEntities cte INNER JOIN Child.Details c ON cte.ChildID = c.ChildID WHERE cte.Row BETWEEN @Start+1 AND @Start+@Limit ORDER BY cte.Row ASC

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