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  • Why do bind1st and bind2nd require constant function objects?

    - by rlbond
    So, I was writing a C++ program which would allow me to take control of the entire world. I was all done writing the final translation unit, but I got an error: error C3848: expression having type 'const `anonymous-namespace'::ElementAccumulator<T,BinaryFunction>' would lose some const-volatile qualifiers in order to call 'void `anonymous-namespace'::ElementAccumulator<T,BinaryFunction>::operator ()(const point::Point &,const int &)' with [ T=SideCounter, BinaryFunction=std::plus<int> ] c:\program files (x86)\microsoft visual studio 9.0\vc\include\functional(324) : while compiling class template member function 'void std::binder2nd<_Fn2>::operator ()(point::Point &) const' with [ _Fn2=`anonymous-namespace'::ElementAccumulator<SideCounter,std::plus<int>> ] c:\users\****\documents\visual studio 2008\projects\TAKE_OVER_THE_WORLD\grid_divider.cpp(361) : see reference to class template instantiation 'std::binder2nd<_Fn2>' being compiled with [ _Fn2=`anonymous-namespace'::ElementAccumulator<SideCounter,std::plus<int>> ] I looked in the specifications of binder2nd and there it was: it took a const AdaptibleBinaryFunction. So, not a big deal, I thought. I just used boost::bind instead, right? Wrong! Now my take-over-the-world program takes too long to compile (bind is used inside a template which is instantiated quite a lot)! At this rate, my nemesis is going to take over the world first! I can't let that happen -- he uses Java! So can someone tell me why this design decision was made? It seems like an odd decision. I guess I'll have to make some of the elements of my class mutable for now...

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  • Set "Start With" value for Oracle sequence dynamically

    - by Allan
    I'm trying to create a release script that can be deployed on multiple databases, but where the data can be merged back together at a later date. The obvious way to handle this is to set the sequence numbers for production data sufficiently high in subsequent deployments to prevent collisions. The problem is in coming up with a release script that will accept the environment number and set the "Start With" value of the sequences appropriately. Ideally, I'd like to use something like this: ACCEPT EnvironNum PROMPT 'Enter the Environment Number: ' --[more scripting] CREATE SEQUENCE seq1 START WITH &EnvironNum*100000; --[more scripting] This doesn't work because you can't evaluate a numeric expression in DDL. Another option is to create the sequences using dynamic SQL via PL/SQL. ACCEPT EnvironNum PROMPT 'Enter the Environment Number: ' --[more scripting] EXEC execute immediate 'CREATE SEQUENCE seq1 START WITH ' || &EnvironNum*100000; --[more scripting] However, I'd prefer to avoid this solution as I generally try to avoid issuing DDL in PL/SQL. Finally, the third option I've come up with is simply to accept the Start With value as a substitution variable, instead of the environment number. Does anyone have a better thought on how to go about this?

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  • SQL Server 2005 Import from Excel

    - by user327045
    I'd like to know what my best option would be to import data from an excel file on a weekly or monthly basis. At first, I thought I would use SSIS, but after much struggle with seemingly simple tasks, I'm starting to rethink my plan. Would it be better/easier to just write the SQL by hand or use the services of an SSIS package? The basic process will be as follows: A separate process will download an .xls file to a local fileshare. The xls file will have a filename like: 'myfilename MON YY'. I will need to read the month and year from the the filename, reformat it to a sql date and then query a DimDate table to find the corresponding date key. For each row (after the first 2 header rows), insert the data with the date key, unless the row is a total row, then ignore. Here are some of the issues I've been encountering with SSIS: I can parse the date string from a flat file datasource, but can't seem to do it with an excel data source. Also, once parsed, i cannot seem to convert the string to a date in order to perform the lookup for the date key. For example, I want to do something like this: select DateKey from DimDate where ActualDate = convert(datetime, '01-' + 'JAN-10', 120) but i don't think it is possible to use the 'convert' or 'datetime' keywords in an expression builder. I have been also unable to find where I can edit the SQL to ignore the first 2 rows of data. I'm very skeptical of using SSIS because it seems like a Kludgy way of doing something that can probably be accomplished more efficiently writing the SQL yourself, but I may be forced to use SSIS. Thoughts?

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  • Tools\addin's for formating or cleaning up xaml?

    - by cody
    I'm guessing these don't exist since I searched around for these but I'm looking for a few tools: 1) A tool that cleans up my xaml so that the properties of elements are consistent through a file. I think enforcing that consistence would make the xaml easier to read. Maybe there could be a hierarchy of what comes first but if not alphabetical might work. Example before: TextBox Name="myTextBox1" Grid.Row="3" Grid.Column="1" Margin="4" TextBox Grid.Column="1" Margin="4" Name="t2" Grid.Row="3" Example after: TextBox Name="myTextBox1" Grid.Row="3" Grid.Column="1" Margin="4" TextBox Name="t2" Grid.Row="3" Grid.Column="1" Margin="4" (note < / has been remove from the above since control seem to have issues parsing whe the after section was added) 2) Along the same lines as above, to increase readability, a tool to align properties, so from the above code example similar props would start in the same place. <TextBox Name="myTextBox1" Grid.Row="3" Grid.Column="1" Margin="4"/> <TextBox Name="t2" Grid.Row="3" Grid.Column="1" Margin="4"/> I know VS has default settings for XAML documents so props can be on one line or separate lines so maybe if there was a tool as described in (1) this would not be needed...but it would still be nice if you like your props all on one line. 3) A tool that adds X to the any of the Grid.Row values and Y to any of the Grid.Column values in the selected text. Every time I add a new row\column I have to go manually fix these. From my understanding Expression Blend can help with this but seem excessive to open Blend just to increment some numbers (and just don't grok Blend). Maybe vs2010 with the designer will help but right now I'm on VS08 and Silverlight. Any one know of any tools to help with this? Anyone planning to write something like this...I'm looking at you JetBrains and\or DevExpress. Thanks.

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  • Silverlight MVVM Confusion: Updating Image Based on State

    - by senfo
    I'm developing a Silverlight application and I'm trying to stick to the MVVM principals, but I'm running into some problems changing the source of an image based on the state of a property in the ViewModel. For all intents and purposes, you can think of the functionality I'm implementing as a play/pause button for an audio app. When in the "Play" mode, IsActive is true in the ViewModel and the "Pause.png" image on the button should be displayed. When paused, IsActive is false in the ViewModel and "Play.png" is displayed on the button. Naturally, there are two additional images to handle when the mouse hovers over the button. I thought I could use a Style Trigger, but apparently they're not supported in Silverlight. I've been reviewing a forum post with a question similar to mine where it's suggested to use the VisualStateManager. While this might help with changing the image for hover/normal states, the part missing (or I'm not understanding) is how this would work with a state set via the view model. The post seems to apply only to events rather than properties of the view model. Having said that, I also haven't successfully completed the normal/hover affects, either. Below is my Silverlight 4 XAML. It should also probably be noted I'm working with MVVM Light. <UserControl x:Class="Foo.Bar.MyUserControl" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" mc:Ignorable="d" d:DesignHeight="100" d:DesignWidth="200"> <UserControl.Resources> <Style x:Key="MyButtonStyle" TargetType="Button"> <Setter Property="IsEnabled" Value="true"/> <Setter Property="IsTabStop" Value="true"/> <Setter Property="Background" Value="#FFA9A9A9"/> <Setter Property="Foreground" Value="#FF000000"/> <Setter Property="MinWidth" Value="5"/> <Setter Property="MinHeight" Value="5"/> <Setter Property="Margin" Value="0"/> <Setter Property="HorizontalAlignment" Value="Left" /> <Setter Property="HorizontalContentAlignment" Value="Center"/> <Setter Property="VerticalAlignment" Value="Top" /> <Setter Property="VerticalContentAlignment" Value="Center"/> <Setter Property="Cursor" Value="Hand"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="Button"> <Grid> <Image Source="/Foo.Bar;component/Resources/Icons/Bar/Play.png"> <VisualStateManager.VisualStateGroups> <VisualStateGroup x:Name="Active"> <VisualState x:Name="MouseOver"> <Storyboard> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Source" Storyboard.TargetName="/Foo.Bar;component/Resources/Icons/Bar/Play_Hover.png" /> </Storyboard> </VisualState> </VisualStateGroup> </VisualStateManager.VisualStateGroups> </Image> </Grid> </ControlTemplate> </Setter.Value> </Setter> </Style> </UserControl.Resources> <Grid x:Name="LayoutRoot" Background="White"> <Button Style="{StaticResource MyButtonStyle}" Command="{Binding ChangeStatus}" Height="30" Width="30" /> </Grid> </UserControl> What is the proper way to update images on buttons with the state determined by the view model? Update I changed my Button to a ToggleButton hoping I could use the Checked state to differentiate between play/pause. I practically have it, but I ran into one additional problem. I need to account for two states at the same time. For example, Checked Normal/Hover and Unchecked Normal/Hover. Following is my updated XAML: <UserControl x:Class="Foo.Bar.MyUserControl" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" mc:Ignorable="d" d:DesignHeight="100" d:DesignWidth="200"> <UserControl.Resources> <Style x:Key="MyButtonStyle" TargetType="ToggleButton"> <Setter Property="IsEnabled" Value="true"/> <Setter Property="IsTabStop" Value="true"/> <Setter Property="Background" Value="#FFA9A9A9"/> <Setter Property="Foreground" Value="#FF000000"/> <Setter Property="MinWidth" Value="5"/> <Setter Property="MinHeight" Value="5"/> <Setter Property="Margin" Value="0"/> <Setter Property="HorizontalAlignment" Value="Left" /> <Setter Property="HorizontalContentAlignment" Value="Center"/> <Setter Property="VerticalAlignment" Value="Top" /> <Setter Property="VerticalContentAlignment" Value="Center"/> <Setter Property="Cursor" Value="Hand"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="ToggleButton"> <Grid> <VisualStateManager.VisualStateGroups> <VisualStateGroup x:Name="CommonStates"> <VisualState x:Name="Normal"> <Storyboard> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="Pause"> <DiscreteObjectKeyFrame KeyTime="0"> <DiscreteObjectKeyFrame.Value> <Visibility>Collapsed</Visibility> </DiscreteObjectKeyFrame.Value> </DiscreteObjectKeyFrame> </ObjectAnimationUsingKeyFrames> </Storyboard> </VisualState> <VisualState x:Name="MouseOver"> <Storyboard> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="PlayHover"> <DiscreteObjectKeyFrame KeyTime="0"> <DiscreteObjectKeyFrame.Value> <Visibility>Visible</Visibility> </DiscreteObjectKeyFrame.Value> </DiscreteObjectKeyFrame> </ObjectAnimationUsingKeyFrames> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="Play"> <DiscreteObjectKeyFrame KeyTime="0"> <DiscreteObjectKeyFrame.Value> <Visibility>Collapsed</Visibility> </DiscreteObjectKeyFrame.Value> </DiscreteObjectKeyFrame> </ObjectAnimationUsingKeyFrames> </Storyboard> </VisualState> </VisualStateGroup> <VisualStateGroup x:Name="CheckStates"> <VisualState x:Name="Checked"> <Storyboard> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="Pause"> <DiscreteObjectKeyFrame KeyTime="0"> <DiscreteObjectKeyFrame.Value> <Visibility>Visible</Visibility> </DiscreteObjectKeyFrame.Value> </DiscreteObjectKeyFrame> </ObjectAnimationUsingKeyFrames> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="Play"> <DiscreteObjectKeyFrame KeyTime="0"> <DiscreteObjectKeyFrame.Value> <Visibility>Collapsed</Visibility> </DiscreteObjectKeyFrame.Value> </DiscreteObjectKeyFrame> </ObjectAnimationUsingKeyFrames> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="PlayHover"> <DiscreteObjectKeyFrame KeyTime="0"> <DiscreteObjectKeyFrame.Value> <Visibility>Collapsed</Visibility> </DiscreteObjectKeyFrame.Value> </DiscreteObjectKeyFrame> </ObjectAnimationUsingKeyFrames> </Storyboard> </VisualState> <VisualState x:Name="Unchecked" /> </VisualStateGroup> </VisualStateManager.VisualStateGroups> <Image x:Name="Play" Source="/Foo.Bar;component/Resources/Icons/Bar/Play.png" /> <Image x:Name="Pause" Source="/Foo.Bar;component/Resources/Icons/Bar/Pause.png" Visibility="Collapsed" /> <Image x:Name="PlayHover" Source="/Foo.Bar;component/Resources/Icons/Bar/Play_Hover.png" Visibility="Collapsed" /> <Image x:Name="PauseHover" Source="/Foo.Bar;component/Resources/Icons/Bar/Pause_Hover.png" Visibility="Collapsed" /> </Grid> </ControlTemplate> </Setter.Value> </Setter> </Style> </UserControl.Resources> <Grid x:Name="LayoutRoot" Background="White"> <ToggleButton Style="{StaticResource MyButtonStyle}" IsChecked="{Binding IsPlaying}" Command="{Binding ChangeStatus}" Height="30" Width="30" /> </Grid> </UserControl>

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  • Is there any way to filter certain things in pages served by IIS?

    - by Ruslan
    Hello, This is my first time posting here so please keep that in mind... I'll try to be short and get right to defining the problem. We have an ASP.NET 2 application (eCommerce package) running on IIS (Windows Server 2003). The main site's page(s) are using plain HTTP (no SSL), but the whole checkout process and the shopping cart page is using SSL (HTTPS). Now, the problem is that the site's header is located in a template file, and inside it it has a plain HTML 'img' tag calling an image with the "http://" portion hard-coded into it... This header appears on absolutely every page (including the https pages), and due to its insecure image tag, a warning box pops up in IE on every stage of the checkout process... Now, the problem: The live application cannot be touched in any way (no changes can be made to the template (so simply changing "http://" to "//" is not an option), IIS cannot be restarted, and the website/app pool cannot be restarted). Is there any way in the world (maybe plugin for IIS or a setting somewhere) that I can filter the pages right before they are served to replace the '<img src="http://example.com/image.jpg">' with '<img src="//example.com/image.jpg">' in the final HTML? Possibly via a regular expression or something? Thanks to everybody in advance.

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  • Binding a Value from a View-Model to the View-Model of a child User Control in Silverlight?

    - by andrej351
    Hi there, So i have a UserControl for one of my Views and have another 'child' UserControl inside that. The outer 'parent' UserControl has a Collection on its View-Model and a Grid control on it to display a list of Items. I want to place another UserControl inside this UserControl to display a form representing the details of one Item. The outer / parent UserControl's View-Model already has a property on it to hold the currently selected Item and i would like to bind this to a DependancyProperty on the inner / child UserControl. I would then like to bind that DependancyProperty to a property on the child UserControl's View-Model. I can then set the DependancyProperty once in XAML with a binding expression and have the child UserControl do all its work in its View-Model like it should. The code i have looks like this.. Parent UserControl: <UserControl x:Class="ItemsListView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" DataContext="{Binding Source={StaticResource ServiceLocator}, Path=ItemsListViewModel}"> <!-- Grid Control here... --> <ItemDetailsView Item="{Binding Source={StaticResource ServiceLocator}, Path=ItemsListViewModel.SelectedItem}" /> </UserControl> Child UserControl: <UserControl x:Class="ItemDetailsView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" DataContext="{Binding Source={StaticResource ServiceLocator}, Path=ItemDetailsViewModel}" ItemDetailsView.Item="{Binding Source={StaticResource ServiceLocator}, Path=ItemDetailsViewModel.Item, Mode=TwoWay}"> <!-- Form controls here... --> </UserControl> The selected Item is bound to the DependancyProperty fine. However from the DependancyProperty to the child View-Model does not. I've used this sort of apporach in a WPF app without problems. It appears to be a situation where there are two concurrent bindings which need to work but with the same target for two sources. Why won't the second (in the child UserControl) binding work?? Is there a way to acheive the behaviour I'm after?? Cheers.

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  • Why are references compacted inside Perl lists?

    - by parkan
    Putting a precompiled regex inside two different hashes referenced in a list: my @list = (); my $regex = qr/ABC/; push @list, { 'one' => $regex }; push @list, { 'two' => $regex }; use Data::Dumper; print Dumper(\@list); I'd expect: $VAR1 = [ { 'one' => qr/(?-xism:ABC)/ }, { 'two' => qr/(?-xism:ABC)/ } ]; But instead we get a circular reference: $VAR1 = [ { 'one' => qr/(?-xism:ABC)/ }, { 'two' => $VAR1->[0]{'one'} } ]; This will happen with indefinitely nested hash references and shallowly copied $regex. I'm assuming the basic reason is that precompiled regexes are actually references, and references inside the same list structure are compacted as an optimization (\$scalar behaves the same way). I don't entirely see the utility of doing this (presumably a reference to a reference has the same memory footprint), but maybe there's a reason based on the internal representation Is this the correct behavior? Can I stop it from happening? Aside from probably making GC more difficult, these circular structures create pretty serious headaches. For example, iterating over a list of queries that may sometimes contain the same regular expression will crash the MongoDB driver with a nasty segfault (see https://rt.cpan.org/Public/Bug/Display.html?id=58500)

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  • Object-oriented GUI development in python

    - by ptabatt
    Hey guys, new programmer here. I have an assignment for class and I'm stuck... What I need to do is a create a GUI that gives someone a basic arithmetic problem in one box, asks the person to answer it, evaluates it, and tells you if you're right or wrong... Basically, what I have is this: [code] class Lesson(Frame): def init (self, parent=None): Frame.init(self, parent) self.pack() Lesson.make_widgets(self) def make_widgets(self): Label(self, text="").pack(side=TOP) ent = Entry(self) self.a = randrange(1,10) self.b = randrange(1,10) self.expr = choice(["+","-"]) ent.insert(END, str(self.a) + str(self.expr) + str(self.a)) [/code] I've broken this down into many little steps and basically, what I'm trying to do right now is insert a default random expression into the first entry widget. When I run this code, I just get a blank Label. Why is that? How can I put a something like "7+7" into the box? If you absolutely need background to the problem, it's question #3 on this link. http://reed.cs.depaul.edu/lperkovic/csc242/homeworks/Homework8.html -Thanks for all help in advance.

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  • A weird crash...

    - by Nima
    Hi, I have a piece of code that runs in debug mode in VS2008, C++. The problem is that when I am debugging the code line by line, at a very weird point of the code, it crashes and says: debug assertion faild. Expression: _BLOCK_TYPE_IS_VALID(pHead-nBlockUse) The crash point is on the first closed curly bracket (after mesh-edges[e].needsUpdate=false;) I don't understand why on a curly bracket? does that make sense to you guys? Can anybody help me understanding what is going on..? for(int e=0; e<mesh->edges.size(); e++) { if(mesh->edges[e].valid && mesh->edges[e].v[0]>=0 && mesh->edges[e].v[1]>=0 && mesh->points[mesh->edges[e].v[0]].writable && mesh->points[mesh->edges[e].v[1]].writable) { //update v_hat and its corresponding error DecEdge Current = DecEdge(e); pair<Point, float> ppf = computeVhat(e); Current.v_hat = ppf.first; Current.error = ppf.second; edgeSoup.push(Current); mesh->edges[e].needsUpdate=false; } }

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  • Differences between Assembly Code output of the same program

    - by ultrajohn
    I have been trying to replicate the buffer overflow example3 from this article aleph one I'm doing this as a practice for a project in a computer security course i'm taking so please, I badly need your help. I've been the following the example, performing the tasks as I go along. My problem is the assembly code dumped by gdb in my computer (i'm doing this on a debian linux image running on VM Ware) is different from that of the example in the article. There are some constructs which I find confusing. Here is the one from my computer: here is the one from the article... Dump of assembler code for function main: 0x8000490 <main>: pushl %ebp 0x8000491 <main+1>: movl %esp,%ebp 0x8000493 <main+3>: subl $0x4,%esp 0x8000496 <main+6>: movl $0x0,0xfffffffc(%ebp) 0x800049d <main+13>: pushl $0x3 0x800049f <main+15>: pushl $0x2 0x80004a1 <main+17>: pushl $0x1 0x80004a3 <main+19>: call 0x8000470 <function> 0x80004a8 <main+24>: addl $0xc,%esp 0x80004ab <main+27>: movl $0x1,0xfffffffc(%ebp) 0x80004b2 <main+34>: movl 0xfffffffc(%ebp),%eax 0x80004b5 <main+37>: pushl %eax 0x80004b6 <main+38>: pushl $0x80004f8 0x80004bb <main+43>: call 0x8000378 <printf> 0x80004c0 <main+48>: addl $0x8,%esp 0x80004c3 <main+51>: movl %ebp,%esp 0x80004c5 <main+53>: popl %ebp 0x80004c6 <main+54>: ret 0x80004c7 <main+55>: nop As you can see, there are differences between the two. I'm confuse and I can't understand totally the assembly code from my computer. I would like to know the differences between the two. How is pushl different from push, mov vs movl , and so on... what does the expression 0xhexavalue(%register) means? I am sorry If I'm asking a lot, But I badly need your help. Thanks for the help really...

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  • d2: assigning ranges/iterators to array slices

    - by modchan
    Consider following code: enum size = 16; double[size] arr1 = [...]; double[size] arr2 = [...]; process = (double x) { return (x + 1); }; arr2[] = map!(process)(arr1[]); // here I have trouble converting results of map back to my plain array. Problem applies not only to map, but also to take, repeat and all those fine tools from std.algorithm and std.range that operate on ranges. On this assignment, I get Error: cannot implicitly convert expression (map(arr1[])) of type Result to double[]. How can I evaluate range to array without using uint i = 0; foreach (x; map!(process)(arr1[])) { arr2[i] = x; i++; } ? Additionally, can someone please explain, why I must call map!(process)(arr1[]) instead of map!(process)(arr1) with static arrays? Shouldn't static arrays be compatible with dynamic for means of iteration, or I don't get something? Also, it seems that straightforward enumeration syntax foreach (index, item; sequence) does not work for ranges - are there workarounds? I guess the reason is the same as why ranges cannot be assigned to array slices.

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  • Is there a practical benefit to casting a NULL pointer to an object and calling one of its member fu

    - by zdawg
    Ok, so I know that technically this is undefined behavior, but nonetheless, I've seen this more than once in production code. And please correct me if I'm wrong, but I've also heard that some people use this "feature" as a somewhat legitimate substitute of a lacking aspect of the current C++ standard, namely, the inability to obtain the address (well, offset really) of a member function. For example, this is out of a popular implementation of a PCRE (Perl-compatible Regular Expression) library: #ifndef offsetof #define offsetof(p_type,field) ((size_t)&(((p_type *)0)->field)) #endif One can debate whether the exploitation of such a language subtlety in a case like this is valid or not, or even necessary, but I've also seen it used like this: struct Result { void stat() { if(this) // do something... else // do something else... } }; // ...somewhere else in the code... ((Result*)0)->stat(); This works just fine! It avoids a null pointer dereference by testing for the existence of this, and it does not try to access class members in the else block. So long as these guards are in place, it's legitimate code, right? So the question remains: Is there a practical use case, where one would benefit from using such a construct? I'm especially concerned about the second case, since the first case is more of a workaround for a language limitation. Or is it? PS. Sorry about the C-style casts, unfortunately people still prefer to type less if they can.

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  • How do I tell nant to only call csc when there are cs files in to compile?

    - by rob_g
    In my NAnt script I have a compile target that calls csc. Currently it fails because no inputs are specified: <target name="compile"> <csc target="library" output="${umbraco.bin.dir}\Mammoth.${project::get-name()}.dll"> <sources> <include name="project/*.cs" /> </sources> <references> </references> </csc> </target> How do I tell NAnt to not execute the csc task if there are no CS files? I read about the 'if' attribute but am unsure what expression to use with it, as ${file::exists('*.cs')} does not work. The build script is a template for Umbraco (a CMS) projects and may or may not ever have .cs source files in the project. Ideally I would like to not have developers need to remember to modify the NAnt script to include the compile task when .cs files are added to the project (or exclude it when all .cs files are removed).

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  • Type result with Ternary operator in C#

    - by Vaccano
    I am trying to use the ternary operator, but I am getting hung up on the type it thinks the result should be. Below is an example that I have contrived to show the issue I am having: class Program { public static void OutputDateTime(DateTime? datetime) { Console.WriteLine(datetime); } public static bool IsDateTimeHappy(DateTime datetime) { if (DateTime.Compare(datetime, DateTime.Parse("1/1")) == 0) return true; return false; } static void Main(string[] args) { DateTime myDateTime = DateTime.Now; OutputDateTime(IsDateTimeHappy(myDateTime) ? null : myDateTime); Console.ReadLine(); ^ } | } | // This line has the compile issue ---------------+ On the line indicated above, I get the following compile error: Type of conditional expression cannot be determined because there is no implicit conversion between '< null ' and 'System.DateTime' I am confused because the parameter is a nullable type (DateTime?). Why does it need to convert at all? If it is null then use that, if it is a date time then use that. I was under the impression that: condition ? first_expression : second_expression; was the same as: if (condition) first_expression; else second_expression; Clearly this is not the case. What is the reasoning behind this? (NOTE: I know that if I make "myDateTime" a nullable DateTime then it will work. But why does it need it? As I stated earlier this is a contrived example. In my real example "myDateTime" is a data mapped value that cannot be made nullable.)

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  • How do I bind arrays to columns in a WPF datagrid

    - by user1432917
    I have a Log object that contains a list of Curve objects. Each curve has a Name property and an array of doubles. I want the Name to be in the column header and the data below it. I have a user control with a datagid. Here is the XAML; <UserControl x:Class="WellLab.UI.LogViewer" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" mc:Ignorable="d" d:DesignHeight="500" d:DesignWidth="500"> <Grid> <StackPanel Height="Auto" HorizontalAlignment="Stretch" Margin="0" Name="stackPanel1" VerticalAlignment="Stretch" Width="Auto"> <ToolBarTray Height="26" Name="toolBarTray1" Width="Auto" /> <ScrollViewer Height="Auto" Name="scrollViewer1" Width="Auto" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Visible" CanContentScroll="True" Background="#E6ABA4A4"> <DataGrid AutoGenerateColumns="True" Height="Auto" Name="logDataGrid" Width="Auto" ItemsSource="{Binding}" HorizontalAlignment="Left"> </DataGrid> </ScrollViewer> </StackPanel> </Grid> In the code behind I have figured out how to create columns and name them, but I have not figured out how to bind the data. public partial class LogViewer { public LogViewer(Log log) { InitializeComponent(); foreach (var curve in log.Curves) { var data = curve.GetData(); var col = new DataGridTextColumn { Header = curve.Name }; logDataGrid.Columns.Add(col); } } } I wont even show the code I tried to use to bind the array "data", since nothing even came close. I am sure I am missing something simple, but after hours of searching the web, I have to come begging for an answer.

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  • Vector insert() causes program to crash

    - by wrongusername
    This is the first part of a function I have that's causing my program to crash: vector<Student> sortGPA(vector<Student> student) { vector<Student> sorted; Student test = student[0]; cout << "here\n"; sorted.insert(student.begin(), student[0]); cout << "it failed.\n"; ... It crashes right at the sorted part because I can see "here" on the screen but not "it failed." The following error message comes up: Debug Assertion Failed! (a long path here...) Expression: vector emplace iterator outside range For more information on how your program can cause an assertion failure, see the Visual C++ documentation on asserts. I'm not sure what's causing the problem now, since I have a similar line of code elsewhere student.insert(student.begin() + position(temp, student), temp); that does not crash (where position returns an int and temp is another declaration of a struct Student). What can I do to resolve the problem, and how is the first insert different from the second one?

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  • Can't use Visual Studio 2008 Designer with MVVMLight V3 SP1

    - by mcauthorn
    I wish I knew what I did to cause this, but I cannot use the Visual Studio 2008 Designer at all with with MVVMLight templates. I receive a "Could not create an instance of type 'ViewModelLocator'. in any of my xaml pages. The application builds and runs fine but only the designer is broken. In the App.xaml is <Application x:Class="ExcelReportGenerator.App" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:vm="clr-namespace:ExcelReportGenerator.ViewModel" xmlns:res="clr-namespace:ExcelReportGenerator.Resources" Startup="Application_Startup" mc:Ignorable="d"> <Application.Resources> <!--Global View Model Locator--> <vm:ViewModelLocator x:Key="Locator" d:IsDataSource="True" /> </Application.Resources> I even receive the error when I create a brand new MVVMLight application. The interesting thing is if I use an express version of VS2010 I can view, edit and work in designer just fine. As much as I would love to go to VS2010, I can't right now convince IT to make that move.

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  • problems selecting a mutliple select value from database in Rails

    - by Ramy
    From inside of a form_for in rails, I'm inserting multiple select values into the database, like this: <div class="new-partner-form"> <%= form_for [:admin, matching_profile.partner, matching_profile], :html => {:id => "edit_profile", :multipart => true} do |f| %> <%= f.submit "Submit", :class => "hidden" %> <div class="rounded-block quarter-wide radio-group"> <h4>Exclude customers from source:</h4> <%= f.select :source, User.select(:source).group(:source).order(:source).map {|u| [u.source,u.source]}, {:include_blank => false}, {:multiple => true} %> <%= f.error_message_on :source %> </div> I'm then trying to pull the value from the database like this: def does_not_contain_source(matching_profiles) Expression.select(matching_profiles, :source) do |keyword| Rails.logger.info("Keyword is : " + keyword) @customer_source_tokenizer ||= Tokenizer.new(User.select(:source).where("id = ?", self.owner_id).map {|u| u.source}[0]) #User.select("source").where("id = ?", self.owner_id).to_s) @customer_source_tokenizer.divergent?(keyword) end end but getting this: ExpressionErrors: Bad syntax: --- - "" - B - "" this is what the value is in the database but it seems to choke when i access it this way. What's the right way to do this?

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  • C standard addressing simplification inconsistency

    - by Chris Lutz
    Section §6.5.3.2 "Address and indirection operators" ¶3 says (relevant section only): The unary & operator returns the address of its operand. ... If the operand is the result of a unary * operator, neither that operator nor the & operator is evaluated and the result is as if both were omitted, except that the constraints on the operators still apply and the result is not an lvalue. Similarly, if the operand is the result of a [] operator, neither the & operator nor the unary * that is implied by the [] is evaluated and the result is as if the & operator were removed and the [] operator were changed to a + operator. ... This means that this: int *i = NULL; printf("%p", (void *) (&*i) ); printf("%p", (void *) (&i[10]) ); Should be perfectly legal, printing the null pointer (probably 0) and the null pointer plus 10 (probably 10). The standard seems very clear that both of those cases are required to be optimized. However, it doesn't seem to require the following to be optimized: struct { int a; short b; } *s = 0; printf("%p", (void *) (&s->b) ); This seems awfully inconsistent. I can see no reason that the above code shouldn't print the null pointer plus sizeof(int) (possibly 4). Simplifying a &-> expression is going to be the same conceptually (IMHO) as &[], a simple address-plus-offset. It's even an offset that's going to be determinable at compile time, rather than potentially runtime with the [] operator. Is there anything in the rationale about why this is so seemingly inconsistent?

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  • Using ADO.NET Entities LINQ Provider to model complex SQL Queries?

    - by Ivan Zlatanov
    What I find really powerful in ADO.NET Entities or LINQ to SQL, is the ability to model complex queries. I really don't need the mappings that Entities or LINQ to SQL are doing for me - I just need the ability to model complex expressions that can be translated into T-SQL. My question is - am I abusing too much? Can I use the Entity Framework for modeling queries and just that? Should I? I know I can write my own custom LINQ to SQL provider, but that is just not possible to handle in the time spans I have. What is the best approach to model complex T-SQL queries? How do you handle conditional group byes, orders, joins, unions etc in the OOP world? Using StringBuilders for this kind of job feels too ugly and harder to maintain given the possibilities we have with Expression Trees. When I use StringBuilder to model a complex SQL Query I feel kind of guilty! I feel the same way as when I have to hard code any number into my code that is different than 0 or 1. Feeling that makes you ask yourself if there is a better and cleaner way of doing it... I must mention that I am using C# 4.0, but I am not specifically looking for an answer in this language, but rather in the domain of CLR 4.

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  • Help me clean up this crazy lambda with the out keyword

    - by Sarah Vessels
    My code looks ugly, and I know there's got to be a better way of doing what I'm doing: private delegate string doStuff( PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt ); private bool tryEncryptPassword( doStuff encryptPassword, out string errorMessage ) { ...get some variables... string encryptedPassword = encryptPassword(encrypter, publicKey, privateKey, out salt); ... } This stuff so far doesn't bother me. It's how I'm calling tryEncryptPassword that looks so ugly, and has duplication because I call it from two methods: public bool method1(out string errorMessage) { string rawPassword = "foo"; return tryEncryptPassword( (PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt) => encrypter.EncryptPasswordAndDoStuff( // Overload 1 rawPassword, publicKey, privateKey, out salt ), out errorMessage ); } public bool method2(SecureString unencryptedPassword, out string errorMessage) { return tryEncryptPassword( (PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt) => encrypter.EncryptPasswordAndDoStuff( // Overload 2 unencryptedPassword, publicKey, privateKey, out salt ), out errorMessage ); } Two parts to the ugliness: I have to explicitly list all the parameter types in the lambda expression because of the single out parameter. The two overloads of EncryptPasswordAndDoStuff take all the same parameters except for the first parameter, which can either be a string or a SecureString. So method1 and method2 are pretty much identical, they just call different overloads of EncryptPasswordAndDoStuff. Any suggestions? Edit: if I apply Jeff's suggestions, I do the following call in method1: return tryEncryptPassword( (encrypter, publicKey, privateKey) => { var result = new EncryptionResult(); string salt; result.EncryptedValue = encrypter.EncryptPasswordAndDoStuff( rawPassword, publicKey, privateKey, out salt ); result.Salt = salt; return result; }, out errorMessage ); Much the same call is made in method2, just with a different first value to EncryptPasswordAndDoStuff. This is an improvement, but it still seems like a lot of duplicated code.

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  • How can I define a verb in J that applies a different verb alternately to each atom in a list?

    - by Gregory Higley
    Imagine I've defined the following name in J: m =: >: i. 2 4 5 This looks like the following: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 I want to create a monadic verb of rank 1 that applies to each list in this list of lists. It will double (+:) or add 1 (>:) to each alternate item in the list. If we were to apply this verb to the first row, we'd get 2 3 6 5 10. It's fairly easy to get a list of booleans which alternate with each item, e.g., 0 1 $~{:$ m gives us 0 1 0 1 0. I thought, aha! I'll use something like +:`>: @. followed by some expression, but I could never quite get it to work. Any suggestions? UPDATE The following appears to work, but perhaps it can be refactored into something more elegant by a J pro. poop =: monad define (($ y) $ 0 1 $~{:$ y) ((]+:)`(]:) @. [)"0 y )

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  • NHibernate query against the key field of a dictionary (map)

    - by Carl Raymond
    I have an object model where a Calendar object has an IDictionary<MembershipUser, Perms> called UserPermissions, where MembershipUser is an object, and Perms is a simple enumeration. This is in the mapping file for Calendar as <map name="UserPermissions" table="CalendarUserPermissions" lazy="true" cascade="all"> <key column="CalendarID"/> <index-many-to-many class="MembershipUser" column="UserGUID" /> <element column="Permissions" type="CalendarPermission" not-null="true" /> </map> Now I want to execute a query to find all calendars for which a given user has some permission defined. The permission is irrelevant; I just want a list of the calendars where a given user is present as a key in the UserPermissions dictionary. I have the username property, not a MembershipUser object. How do I build that using QBC (or HQL)? Here's what I've tried: ISession session = SessionManager.CurrentSession; ICriteria calCrit = session.CreateCriteria<Calendar>(); ICriteria userCrit = calCrit.CreateCriteria("UserPermissions.indices"); userCrit.Add(Expression.Eq("Username", username)); return calCrit.List<Calendar>(); This constructed invalid SQL -- the WHERE clause contained WHERE membership1_.Username = @p0 as expected, but the FROM clause didn't include the MemberhipUsers table. Also, I really had to struggle to learn about the .indices notation. I found it by digging through the NHibernate source code, and saw that there's also .elements and some other dotted notations. Where's a reference to the allowed syntax of an association path? I feel like what's above is very close, and just missing something simple.

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  • Why is a Silverlight application created from an exported template show a blank screen in the browse

    - by Edward Tanguay
    I created a silverlight app (without website) named TestApp, with one TextBox: <UserControl x:Class="TestApp.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480"> <Grid x:Name="LayoutRoot"> <TextBlock Text="this is a test"/> </Grid> </UserControl> I press F5 and see "this is a test" in my browser (firefox). I select File | Export Template | name it TestAppTemplate and save it. I create a new silverlight app based on the above template. The MainPage.xaml has the exact same XAML as above. I press F5 and see a blank screen in my browser. I look at the HTML source of both of these and they are identical. Everything I have compared in both projects is identical. What do I have to do so that a Silverlight application which is created from my exported template does not show a blank screen?

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