The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘.NET’ Category

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.NET/C#: When XmlSerializer throws “Unable to generate a temporary class (result=1).” / “error CS2001”

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 »

.NET/C#/VB.NET – Default value for generics (via: Stack Overflow)

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);

  1. How do I do this in VB?
  2. If this just returns null (C#) or nothing (VB.NET) then what happens to value types?
  3. 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.

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, 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 | Leave a Comment »

.NET/C#: refactoring some C# 1 code that uses HashTables as a poor mans property bag (via:Stack Overflow)

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 »

.NET/C#: fun with enums and aliases part 2

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 »

.NET/C#: an alias is not the same as a synonym: int versus Int32, etc (fun with enums and aliases part 1)

Posted by jpluimers on 2014/01/28

I was amongst the C# programmers that believe the below table of C# integral types is an alias table. But it is not: it is a synonym table.

C# type .NET Framework Type/
Common Type System
byte System.Byte
sbyte System.SByte
short System.Int16
ushort System.UInt16
int System.Int32
uint System.UInt32
long System.Int64
ulong System.UInt64

You can use the common type system types as coding standard, or prefer the C# types. There are arguments for both.

I am still in the first group: prefer CTS types. They make changing between .NET languages a lot easier (C# and VB.NET are not the only .NET based CLI languages I use).

And indeed almost everywhere you can exchange the .NET Framework Type and the C# type without changing meaning.

There are two exceptions Read the rest of this entry »

Posted in .NET, C#, Delphi, Development, Jon Skeet, Software Development | 1 Comment »

Faking num lock, caps lock and scroll lock leds – About My Code

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 »

Word 2007/2010/2013: Enabling the Word Developer Tab on the ribbon (via: Andrew Coates ::: MSFT – Site Home – MSDN Blogs)

Posted by jpluimers on 2014/01/16

This is one of the things I tend to forget, as you do it once per machine, and the place to do it is not logical to me.

I mainly use it to quickly record a Macro (boy, I wish Office had a TemporaryMacro feature like Visual Studio had. Alas no more: Macro Recording/Playback has been removed in Visual Studio 2012).

The logical place for me would be to have a context-menu on the ribbon where you can enable the Developer tab.

Anyway, this is how to enable the Developer tab in Word 2007/2010/2013: Read the rest of this entry »

Posted in Development, Office, Office 2007, Office 2010, Office 2013, Power User, Software Development, Visual Studio 11, Visual Studio 2002, Visual Studio 2003, Visual Studio 2005, Visual Studio 2008, Visual Studio 2010, Visual Studio and tools, Word | Leave a Comment »

.NET/C#: you cannot do string? because Nullable is for value type, and string is a reference type

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 »

When two types are not the same: Assembly Load Contexts Subtleties (via: All Your Base Are Belong To Us)

Posted by jpluimers on 2014/01/09

Reading c# – Type.IsSubclassOf does not behave as expected – Stack Overflow, I found this very interesting link via Assembly Load Contexts Subtleties at Sasha Goldshtein’s blog (I love the name of the blog: All Your Base Are Belong To Us).

He explains the reasons for the error message

System.InvalidCastException: Unable to cast object of type ‘Plugin.MyPlugin’ to type ‘Plugin.MyPlugin’.

Actually his blog entry is an abstract of a 200+ page thesis on  that is also recommended reading: Flexible Dynamic Linkin for .NET (by Anders Aaltonen, Alex Buckley and Susan Eisenbach).

–jeroen

via:

Posted in .NET, .NET 3.5, .NET 4.0, .NET 4.5, .NET CF, C#, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »

.NET/Visual Studio: The ContextSwitchDeadlock doesn’t necessarily mean your code has an issue.

Posted by jpluimers on 2014/01/07

Thanks Pedro! (emphasis below is mine)

The ContextSwitchDeadlock doesn’t necessarily mean your code has an issue, just that there is a potential.

If you go to Debug > Exceptions in the menu and expand the “Managed Debugging Assistants”, you will find ContextSwitchDeadlock is enabled.

If you disable this, VS will no longer warn you when items are taking a long time to process.

In some cases you may validly have a long-running operation.

It’s also helpful if you are debugging and have stopped on a line while this is processing – you don’t want it to complain before you’ve had a chance to dig into an issue.

–jeroen

via: c# – Visual Studio: ContextSwitchDeadlock – Stack Overflow.

Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, Development, Software Development, Visual Studio 11, Visual Studio 2005, Visual Studio 2008, Visual Studio 2010, Visual Studio and tools | Leave a Comment »

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