Category Archives: Programming

VisualStudio Output Window Error highlighter

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In Visual Studio 2015, the Output Window contains plain text, with no colorizing or highlighting of any kind. This makes it hard to spot some errors in the multitude of output text, for example WPF’s binding errors.

I have long wanted an extension to highlight this kind of errors, so I decided to write one for myself. Very simple, it just puts in red all the lines containing “Error” so that now I can see if I miss any binding error in WPF, definitely saving me a lot of time.

OutputColorizerVSX_Screenshot

Download the extension:

To install it, just run the vsix file and the VSIX Installer will come up and do the job.

Xaml design-time DataContext

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System.Windows.Data Error: 40 : BindingExpression path error: 'Emial' property not found on 'object' ''Customer' (HashCode=49475561)'. BindingExpression:Path=Emial; DataItem='Customer' (HashCode=49475561); target element is 'Label' (Name=''); target property is 'Content' (type 'Object')

This is one of the most frustrating binding errors that happen while writing bindings in xaml. Sometimes, if not careful enough, it might easily get lost in the Visual Studio output window. To reduce the number of such errors and to design the UI more easily, one may benefit of the support of auto-completion while writing xaml bindings in Visual Studio.

To add a design time DataContext:

<Window x:Class="Sample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vm="clr-namespace:Sample.ViewModels"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        Title="MainWindow" Height="350" Width="525"
        mc:Ignorable="d"
        d:DataContext="{d:DesignInstance Type=vm:Customer, IsDesignTimeCreatable=True}">
    <Grid>
        <StackPanel>
            <Label Content="{Binding Emial}" />
        </StackPanel>
    </Grid>
</Window>

Lines 6 and 9 are the ones that do the trick. The Visual Studio designer will use this DataContext object at design time.
Lines 5 and 8 are also needed to instruct the real xaml compiler to ignore this DataContext attribute.

Although I didn’t find any official documentation over the DesignInstance, this extension supports three parameters:

Type – this is the type of the object you want to use as a DataContext at design time (in my case here, I have a simple Customer view-model that has some Name, Address and Email properties).

IsDesignTimeCreatable – if this is true the designer will simply instantiate the type and use it; if it is  false the designer will generate a type with the same properties as the one specified and instantiate that type.

To be “design time creatable” the type must have a constructor with no parameters. If it has, the designer can instantiate it and use it. If the type does not have a default constructor, the designer doesn’t know what parameters to pass to the other constructors so here is where IsDesignTimeCreatable = false helps.

The drawback of using IsDesignTimeCreatable = false is that any properties set in the original type are not visible in the dummy type created and instantiated.

There are some workarounds for using IsDesignTimeCreatable = true like adding a parameterless constructor (perhaps in a derived class and using that class instead), but it all depends on the exact scenario.

CreateList – if true the designer will create a collection of your type and that can be used for bindings to the ItemsSource properties, for example or in another place where a collection is expected.

Now Intellisense shows auto-completion for DataContext members:

xaml-datacontext-designtime

Intellisense documentation for Unity3D API in Visual Studio

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By default, Unity3D 4.6 does not ship with XML documentation for the Unity API, therefore Visual Studio is unable to display documentation in Intellisense.

To fix this, download the file UnityEngine.xml (right-click, Save As…) and copy it to the following Unity folder:

c:\Program Files (x86)\Unity\Editor\Data\Managed\

(Path may be different if Unity was installed in another location than the default one)

folder

Before:

after

After:

before

Note that administrator permission might be required to write to Program Files.

Observable Property C# code snippet

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One of the VS functionality I abuse every day is writing code via the code snippets, those little fill-in code pieces that appear when you press tab twice after writing their mnemonic like propdp[Tab][Tab] for defining a DependencyProperty.

Unfortunately, VS doesn’t come with such a snippet for defining an observable property, which might be particular useful when working with MVVM or/and WPF, most likely because there is more than one way to implement such a property. However, I usually implement them in the same way, something like this:

private string _Name;
public string Name
{
    get { return _Name; }
    set
    {
        if (_Name != value)
        {
            _Name = value;
            RaisePropertyChanged("Name");
        }
    }
}

And the class implements INotifyPropertyChanged and RaisePropertyChanged looks like this:

public void RaisePropertyChanged(params string properties)
{
    var handler = PropertyChanged;
    if (handler != null)
        handler(this, new PropertyChangedEventArgs(prop));
}

In this conditions, when I have to write a lot of observable properties (actually I am using it even if I have to write only one such property), it comes very handy to have a code snippet that generates the property:

propo.snippet:

<?xml version="1.0" encoding="utf-8"?>
<CodeSnippets xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet">
  <CodeSnippet Format="1.0.0">
    <Header>
      <Title>Observable property</Title>
      <Description>Adds a new observable property to the current class.</Description>
      <Shortcut>propo</Shortcut>
    </Header>
    <Snippet>
      <Declarations>
        <Literal>
          <ID>Type</ID>
          <ToolTip>Replace with the type you want your property to have.</ToolTip>
          <Default>PropertyType</Default>
        </Literal>
        <Literal>
          <ID>Name</ID>
          <ToolTip>Replace with the name you want to give to the property.</ToolTip>
          <Default>PropertyName</Default>
        </Literal>
      </Declarations>
      <Code Language="CSharp">
        <![CDATA[private $Type$ _$Name$;
        public $Type$ $Name$
        {
            get { return _$Name$; }
            set
            {
                if (_$Name$ != value)
                {
                    _$Name$ = value;
                    RaisePropertyChanged("$Name$");
                }
            }
        }]]>
      </Code>
    </Snippet>
  </CodeSnippet>
</CodeSnippets>
To install this snippet, save the above xml in a file called propo.snippet and use the Import button in the Visual Studio’s Code Snippets Manager (Tools / Code Snippets Manager).
To use this snippet write propo in a cs file and hit Tab key twice.

Framework vs. library

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Two software terms that programmers use every day. Yet, if you ask programmers what they are, you will most likely receive different answers from one programmer to another. I found out this the other days asking some of my colleagues and I then realized I have a personal definition for library and framework, which, of course, I consider to be the right definition.

For me, a library is a collection of methods and functions (and even classes or other more exotic structures) that help achieve a result, or solve a problem. The application calls the methods in the library to solve its tasks.
A framework, on the other hand, is the abstract structure of an application. To complete the application, the programmer adds code that customize this framework in such a manner that will solve the applications tasks. The framework calls this code when it needs. A framework typically already contains most or some of the logic and the structure of the application and some special points where custom code can be inserted in the default flow to alter it in order to achieve new functionality. Sometimes, framework are very complex and might include programming languages or compilers.
FWVSLIB2

 

And I think that if we look at some examples, the things become quite clear:
  • C Runtime Library – contains functions like sprintf that a programmer can call to format a string.
  • 7-zip compression library – contains functions that a programmer can call to compress or decompress files.
  • ASP.NET is a framework, because you only provide a few missing pieces to the barebone to have your web application.
  • Spring – a framework for Java applications. Again, the programmer just writes some of the missing pieces, the framework does the rest.