Archive for the ‘C# 2.0’ Category
Posted by jpluimers on 2014/02/06
A while ago, I had this error when running an application on a hardened server:
Unhandled Exception:System.InvalidOperationException:
Unable to generate a temporary class (result=1).
error CS2001: Source file 'C:\windows\TEMP\0hocq2nq.0.cs' could not be found error CS2008: No inputs specified
at System.Xml.Serialization.Compiler.Compile(Assembly parent, String ns, XmlSerializerCompilerParameters xmlParameters, Evidence evidence)
at System.Xml.Serialization.TempAssembly.GenerateAssembly(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, Evidence evidence, XmlSerializerCompilerParameters parameters, Assembly assembly, Hashtable assemblies)
at System.Xml.Serialization.TempAssembly..ctor(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, String location, Evidence evidence)
at System.Xml.Serialization.XmlSerializer..ctor(Type type, XmlAttributeOverrides overrides, Type[] extraTypes, XmlRootAttribute root, String defaultNamespace, String location, Evidence evidence)
at System.Xml.Serialization.XmlSerializer..ctor(Type type, XmlAttributeOverrides overrides, Type[] extraTypes, XmlRootAttribute root, String defaultNamespace, String location)
at System.Xml.Serialization.XmlSerializer..ctor(Type type, Type[] extraTypes)
Usually I’m not the first with strange errors, but searching for “Unhandled Exception:System.InvalidOperationException: Unable to generate a temporary class” didn’t get many results.
This was a program running from SSIS under a non-system domain account with very little access.
My first guess was the right now: the XmlSerializer wants to generate a temporary C# file, then compile it into a temporary assembly. Since it cannot generate the C# file because the account does not have access to %windir\TEMP%, the compiler cannot find the (not generated) C# file.
After a few tries, I searched for XmlSerializer without GenerateAssembly, where the first hit ended at Changing where XmlSerializer Outputs Temporary Assemblies – Scott Hanselman.
That post indicated I should try looking for tempFilesLocation in the XmlSerializer context.
That got me these posts: Read the rest of this entry »
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »
Posted by jpluimers on 2014/02/05
Looking for the pesky little differences between C# and VB.NET, I stumbled over this nice question by Micah Martin on default values for generics in VB.NET as compared to C#. Actually there were 3 questions, so I did a bit of post-editing:
How do I create the default for a generic in VB.NET? in C# I can call:
T variable = default(T);
- How do I do this in VB?
- If this just returns null (C#) or nothing (VB.NET) then what happens to value types?
- Is there a way to specify for a custom type what the default value is? For instance what if I want the default value to be the equivalent to calling a parameterless constructor on my class.
User Konrad Rudolph – Stack Overflow. promptly gave three answers:
Question 1:
Dim variable As T ‘ or ‘ Dim variable As T = Nothing ‘ or ‘ Dim variable As New T() Notice that the latter only works if you specifiy either the New or the Structure constraint for the generic type.
Question 2:
For value types all members of the struct are “nulled” out, i.e. all reference type members are set to null (Nothing) and all value types are in turn nulled out. And no, since string is a reference type, it does not result in "" for strings as suggested in the other answer.
Question 3:
No, there’s no way to specify this. There are some threads about this on Stack Overflow already, e.g. here. Jon has posted an excellent explanation why this is.
–jeroen
via: c# – Default value for generics – Stack Overflow.
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Posted by jpluimers on 2014/01/30
A while ago, I was refactoring some C# 1 code that uses HashTables as a poor mans property bag.
The problem was that I felt my code was convoluted, and should be denser, especially avoiding Convert.ChangeType. My code was already much simpler than casting tuples to a superclass.
So I asked this question on StackOverflow: c# – Is there a solution that feels less clumsy than Convert.ChangeType to get the value from a HashTable – Stack Overflow.
User dasblinkenlight showed it could be shortened and explained why (hyperlinks are mine):
Since System.String is sealed, the expression
genericType.IsSubclassOf(stringType)
is the same as
genericType == stringType
Therefore you do not need a call of Convert.ChangeType: you can cast to T by casting to object, like this:
object stringResult; // Note the change of type to "object"
if (haveValue)
stringResult = ((string)properties[propertyName]).Trim();
else
stringResult = string.Empty;
result = (T)stringResult; // It is allowed to cast object to generic T
The original .NET 1.1 code had loads of null checks wrapped if/then/else statements to assign default values for null values.
I wanted to get rid of that, and get code like this: Read the rest of this entry »
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »
Posted by jpluimers on 2014/01/29
In the .NET/C#: fun with enums and aliases part 1 you saw that an enumerated type can specify an underlying type.
The underlying type is limited to a strict set of built-in C# types: , so you cannot use a CTS type for it.
So you might think that you can only define enumeration values by integer constant like this:
namespace BeSharp
{
enum TwoState
{
False = 0,
True = 1,
}
enum ThreeState
{
False = 0,
True = 1,
Unknown = -1,
}
}
Well, you can do it like this too, since Operations between different enum types are allowed in another enum declaration: Read the rest of this entry »
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »
Posted by jpluimers on 2014/01/21
I remember doing this in DOS ages ago (in the Turbo Pascal 5 era) for exactly the same reason: flash the keyboard LEDs to indicate some event was happening, but I’ve yet to find back the source code.
Here is how to do it in Windows using either C# or C: Faking num lock, caps lock and scroll lock leds – About My Code.
–jeroen
via: c# – Way to turn on keyboard’s caps-lock light without actually turning on caps-lock? – Stack Overflow.
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, C++, Development, Pascal, Software Development, Turbo Pascal | Leave a Comment »
Posted by jpluimers on 2014/01/15
At clients, I see quite a few people being confused by this compiler error message:
Error 1 The type 'string' must be a non-nullable value type in order to use it as parameter 'T' in the generic type or method 'System.Nullable'
One of the reasons about the confusion is that a string variable behaves like a value type, but in fact is a reference type because their values can consume a huge amount of memory (thanks User codekaizen).
A few interesting questions on that on StackOverflow:
Anyway, back to the error message above.
Lots of people are confused by it, just see a few questions on StackOverflow: Read the rest of this entry »
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Jon Skeet, Software Development | Leave a Comment »
Posted by jpluimers on 2014/01/01
For a project, I needed to strip the potential Path.DirectorySeparatorChar and Path.AltDirectorySeparatorChar.
Where Path.Combine will combine two paths and insert the DirectorySeparatorChar, I could not find the opposite, so I wrote this little piece of code:
using System.IO;
namespace BeSharp.IO
{
public class PathHelper
{
public static string RemoveTrailingDirectorySeparators(string directory)
{
string result = directory.TrimEnd(Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar);
return result;
}
}
}
–jeroen
via:
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »
Posted by jpluimers on 2013/12/26
My mental association with getting LogicalDrives was always the System.IO namespace, so I’ve always used Directory.GetLogicalDrives Method (System.IO) .
Recently I bumped into Environment.GetLogicalDrives Method (System), and discovered it has been available for the same time: since .NET 1.x.
I was not so much amazed that these methods return exactly the same data, but that they have identical code. Not just a single call to some common code: their code is the same, line by line. In .NET 4, they have the code below. Read the rest of this entry »
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »
Posted by jpluimers on 2013/12/25
StackOverflow user Joe (sorry, no last name) helped me big time by answering my question on Business logic shared by ASP.NET / WinForms: find the location of the assembly to access relative files to it.
Before showing the code at the bottom of this blog post, let me explain the question in more detail:
Basically I was in the midst of refactoring some ‘inherited’ business logic code that – before refactoring – for the ASP.NET side needs to be initialized with an absolute path, but on the WinForms / WPF side only with a relative path to a GetExecutingAssembly directory.
To ease xcopy deployment, I wanted all configuration settings to be relative. But I hadn’t found a common means for these platforms to obtain a directory usable as a root for accessing relative files.
That way I could put identical settings in both the Web.config and App.config, heck even generate them based on a common fragment, whithout having to hard-code absolute path names.
I knew about Assembly.GetExecutingAssembly, but in ASP.NET that location is not where the web site is (both IIS and the WebDevelopment server make use of temporary locations to store the assemblies).
ASP.NET does have Server.MapPath and HostingEnvironment.MapPath, but I didn’t want to make the business logic depend on ASP.NET.
Joe came up with this solution, which works dandy: Read the rest of this entry »
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, ASP.NET, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, F#, Prism, Software Development, VB.NET, VB.NET 10.0, VB.NET 11.0, VB.NET 7.0, VB.NET 7.1, VB.NET 8.0, VB.NET 9.0, Web Development | Leave a Comment »
Posted by jpluimers on 2013/12/17
The Mono.Options single .cs source file seems very well suited for arguments parsing of (especially) console application:
https://github.com/mono/mono/blob/master/mcs/class/Mono.Options/Mono.Options/Options.cs
so it is on my research list, like some other .NET/C# based command line parsing libraries (:
–jeroen
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »
The Wiert Corner - irregular stream of stuff 