Archive for CSharp tag
Experimental LINQ to SQL template
A newer version of this LINQ to SQL template is available.
While SQL Metal does a good job of turning your SQL schema into a set of classes for you it doesn’t let you customize the code generation process.
Usefully there is now a templating system built into Visual Studio 2008 called Text Templates (T4 for short).
Here is a short (369 line) experimental proof-of-concept T4 template I wrote last night that will generate a data context and associated entity classes as a starting point similar to that produced by SqlMetal.
Download of this old version no longer available, see the newer article!
Once downloaded unzip and drop the DataContext.cs.tt into your project and edit line 17 to set the connection string. You can also edit lines 18 and 19 to set the namespace and class name. The lightweight wrappers around database, table and column can be found at the end of the file – they simply wrap the SQL Server Information_Schema views as briefly as possible.
Within seconds Visual Studio should have created a code-behind file for the DataContext named DataContext.cs.cs with your generated code ready to use :) If you don’t like the way the template generates your context you can change it :)
- Processes all and only tables in the database (no views or SP’s)
- Foreign-key relationships are not implemented
- Column attributes for IsDbGenerated, UpdateCheck and AutoSync not implemented
- C# only (sorry Julie)
- Plural and singular naming rules are incomplete
- Can’t modify schema as you could with a designer stage
- Watch a screencast about T4 in action (download, embedded player is awful)
- Grab T4 Editor for IntelliSense within T4 and T4 Template Items for Add New Item… support
- Check out Oleg Sych’s blog for great T4 articles including how to enable the 3.5 compiler for templates
- Learn about T4 debugging
[)amien
Using LINQ to foreach over an enum in C#
I can’t be the only person in the world who wants to foreach over the values of an enum otherwise Enum.GetValues(Type enumType) wouldn’t exist in the framework. Alas it didn’t get any generics love in .NET 2.0 and unhelpfully returns an array.
Thanks to the power of LINQ you can do this:
foreach(CustomerTypes customerType in Enum.GetValues(typeof(CustomerTypes)).Cast<CustomerTypes>())That is okay, but this is more concise:
foreach(CustomerTypes customerType in Enums.Get<CustomerTypes>())The tiny class to achieve that is, of course:
using System.Collections.Generic;
using System.Linq;
public static class Enums {
public static IEnumerable<T> Get<T>() {
return System.Enum.GetValues(typeof(T)).Cast<T>();
}
}Great.
[)amien
Calculating Elf-32 in C# and .NET
Because you can never have enough hashing algorithms at your disposal this one is compatible with the elf_hash function that forms part of the Executable and Linkable Format.
using System;
using System.Security.Cryptography;
public class Elf32 : HashAlgorithm {
private UInt32 hash;
public Elf32() {
Initialize();
}
public override void Initialize() {
hash = 0;
}
protected override void HashCore(byte[] buffer, int start, int length) {
hash = CalculateHash(hash, buffer, start, length);
}
protected override byte[] HashFinal() {
byte[] hashBuffer = UInt32ToBigEndianBytes(hash);
this.HashValue = hashBuffer;
return hashBuffer;
}
public override int HashSize { get { return 32; } }
public static UInt32 Compute(UInt32 polynomial, UInt32 seed, byte[] buffer) {
return CalculateHash(seed, buffer, 0, buffer.Length);
}
private static UInt32 CalculateHash(UInt32 seed, byte[] buffer, int start, int size) {
UInt32 hash = seed;
for (int i = start; i < size; i++)
unchecked {
hash = (hash << 4) + buffer[i];
UInt32 work = (hash & 0xf0000000);
if (work != 0)
hash ^= (work >> 24);
hash &= ~work;
}
return hash;
}
private byte[] UInt32ToBigEndianBytes(UInt32 x) {
return new byte[] {
(byte)((x >> 24) & 0xff),
(byte)((x >> 16) & 0xff),
(byte)((x >> 8) & 0xff),
(byte)(x & 0xff)
};
}
}[)amien
Calculating CRC-64 in C# and .NET
Seeing how the CRC-32 C# class I posted some time ago continues to get lots of Google hits I thought I’d post a CRC-64 version which will no doubt be far less popular being the more limited use. Again, do not use this as a secure message signature, it’s really for backward compatibility with legacy systems.
Unlike the previous CRC-32 version this one uses a pre-generated constant (well, readonly) table as the generation code was quite slow.
using System;
using System.Security.Cryptography;
public class Crc64 : HashAlgorithm {
public const UInt64 DefaultSeed = 0x0;
private static readonly UInt64[] table = new UInt64[] {
0x0000000000000000L, 0x01b0000000000000L, 0x0360000000000000L,
0x02d0000000000000L, 0x06c0000000000000L, 0x0770000000000000L,
0x05a0000000000000L, 0x0410000000000000L, 0x0d80000000000000L,
0x0c30000000000000L, 0x0ee0000000000000L, 0x0f50000000000000L,
0x0b40000000000000L, 0x0af0000000000000L, 0x0820000000000000L,
0x0990000000000000L, 0x1b00000000000000L, 0x1ab0000000000000L,
0x1860000000000000L, 0x19d0000000000000L, 0x1dc0000000000000L,
0x1c70000000000000L, 0x1ea0000000000000L, 0x1f10000000000000L,
0x1680000000000000L, 0x1730000000000000L, 0x15e0000000000000L,
0x1450000000000000L, 0x1040000000000000L, 0x11f0000000000000L,
0x1320000000000000L, 0x1290000000000000L, 0x3600000000000000L,
0x37b0000000000000L, 0x3560000000000000L, 0x34d0000000000000L,
0x30c0000000000000L, 0x3170000000000000L, 0x33a0000000000000L,
0x3210000000000000L, 0x3b80000000000000L, 0x3a30000000000000L,
0x38e0000000000000L, 0x3950000000000000L, 0x3d40000000000000L,
0x3cf0000000000000L, 0x3e20000000000000L, 0x3f90000000000000L,
0x2d00000000000000L, 0x2cb0000000000000L, 0x2e60000000000000L,
0x2fd0000000000000L, 0x2bc0000000000000L, 0x2a70000000000000L,
0x28a0000000000000L, 0x2910000000000000L, 0x2080000000000000L,
0x2130000000000000L, 0x23e0000000000000L, 0x2250000000000000L,
0x2640000000000000L, 0x27f0000000000000L, 0x2520000000000000L,
0x2490000000000000L, 0x6c00000000000000L, 0x6db0000000000000L,
0x6f60000000000000L, 0x6ed0000000000000L, 0x6ac0000000000000L,
0x6b70000000000000L, 0x69a0000000000000L, 0x6810000000000000L,
0x6180000000000000L, 0x6030000000000000L, 0x62e0000000000000L,
0x6350000000000000L, 0x6740000000000000L, 0x66f0000000000000L,
0x6420000000000000L, 0x6590000000000000L, 0x7700000000000000L,
0x76b0000000000000L, 0x7460000000000000L, 0x75d0000000000000L,
0x71c0000000000000L, 0x7070000000000000L, 0x72a0000000000000L,
0x7310000000000000L, 0x7a80000000000000L, 0x7b30000000000000L,
0x79e0000000000000L, 0x7850000000000000L, 0x7c40000000000000L,
0x7df0000000000000L, 0x7f20000000000000L, 0x7e90000000000000L,
0x5a00000000000000L, 0x5bb0000000000000L, 0x5960000000000000L,
0x58d0000000000000L, 0x5cc0000000000000L, 0x5d70000000000000L,
0x5fa0000000000000L, 0x5e10000000000000L, 0x5780000000000000L,
0x5630000000000000L, 0x54e0000000000000L, 0x5550000000000000L,
0x5140000000000000L, 0x50f0000000000000L, 0x5220000000000000L,
0x5390000000000000L, 0x4100000000000000L, 0x40b0000000000000L,
0x4260000000000000L, 0x43d0000000000000L, 0x47c0000000000000L,
0x4670000000000000L, 0x44a0000000000000L, 0x4510000000000000L,
0x4c80000000000000L, 0x4d30000000000000L, 0x4fe0000000000000L,
0x4e50000000000000L, 0x4a40000000000000L, 0x4bf0000000000000L,
0x4920000000000000L, 0x4890000000000000L, 0xd800000000000000L,
0xd9b0000000000000L, 0xdb60000000000000L, 0xdad0000000000000L,
0xdec0000000000000L, 0xdf70000000000000L, 0xdda0000000000000L,
0xdc10000000000000L, 0xd580000000000000L, 0xd430000000000000L,
0xd6e0000000000000L, 0xd750000000000000L, 0xd340000000000000L,
0xd2f0000000000000L, 0xd020000000000000L, 0xd190000000000000L,
0xc300000000000000L, 0xc2b0000000000000L, 0xc060000000000000L,
0xc1d0000000000000L, 0xc5c0000000000000L, 0xc470000000000000L,
0xc6a0000000000000L, 0xc710000000000000L, 0xce80000000000000L,
0xcf30000000000000L, 0xcde0000000000000L, 0xcc50000000000000L,
0xc840000000000000L, 0xc9f0000000000000L, 0xcb20000000000000L,
0xca90000000000000L, 0xee00000000000000L, 0xefb0000000000000L,
0xed60000000000000L, 0xecd0000000000000L, 0xe8c0000000000000L,
0xe970000000000000L, 0xeba0000000000000L, 0xea10000000000000L,
0xe380000000000000L, 0xe230000000000000L, 0xe0e0000000000000L,
0xe150000000000000L, 0xe540000000000000L, 0xe4f0000000000000L,
0xe620000000000000L, 0xe790000000000000L, 0xf500000000000000L,
0xf4b0000000000000L, 0xf660000000000000L, 0xf7d0000000000000L,
0xf3c0000000000000L, 0xf270000000000000L, 0xf0a0000000000000L,
0xf110000000000000L, 0xf880000000000000L, 0xf930000000000000L,
0xfbe0000000000000L, 0xfa50000000000000L, 0xfe40000000000000L,
0xfff0000000000000L, 0xfd20000000000000L, 0xfc90000000000000L,
0xb400000000000000L, 0xb5b0000000000000L, 0xb760000000000000L,
0xb6d0000000000000L, 0xb2c0000000000000L, 0xb370000000000000L,
0xb1a0000000000000L, 0xb010000000000000L, 0xb980000000000000L,
0xb830000000000000L, 0xbae0000000000000L, 0xbb50000000000000L,
0xbf40000000000000L, 0xbef0000000000000L, 0xbc20000000000000L,
0xbd90000000000000L, 0xaf00000000000000L, 0xaeb0000000000000L,
0xac60000000000000L, 0xadd0000000000000L, 0xa9c0000000000000L,
0xa870000000000000L, 0xaaa0000000000000L, 0xab10000000000000L,
0xa280000000000000L, 0xa330000000000000L, 0xa1e0000000000000L,
0xa050000000000000L, 0xa440000000000000L, 0xa5f0000000000000L,
0xa720000000000000L, 0xa690000000000000L, 0x8200000000000000L,
0x83b0000000000000L, 0x8160000000000000L, 0x80d0000000000000L,
0x84c0000000000000L, 0x8570000000000000L, 0x87a0000000000000L,
0x8610000000000000L, 0x8f80000000000000L, 0x8e30000000000000L,
0x8ce0000000000000L, 0x8d50000000000000L, 0x8940000000000000L,
0x88f0000000000000L, 0x8a20000000000000L, 0x8b90000000000000L,
0x9900000000000000L, 0x98b0000000000000L, 0x9a60000000000000L,
0x9bd0000000000000L, 0x9fc0000000000000L, 0x9e70000000000000L,
0x9ca0000000000000L, 0x9d10000000000000L, 0x9480000000000000L,
0x9530000000000000L, 0x97e0000000000000L, 0x9650000000000000L,
0x9240000000000000L, 0x93f0000000000000L, 0x9120000000000000L,
0x9090000000000000L
};
private UInt64 seed;
private UInt64 hash;
public Crc64() {
seed = DefaultSeed;
Initialize();
}
public Crc64(UInt64 seed) {
this.seed = seed;
Initialize();
}
public override void Initialize() {
hash = seed;
}
protected override void HashCore(byte[] buffer, int start, int length) {
hash = CalculateHash(hash, buffer, start, length);
}
protected override byte[] HashFinal() {
byte[] hashBuffer = UInt64ToBigEndianBytes(hash);
this.HashValue = hashBuffer;
return hashBuffer;
}
public override int HashSize {
get { return 64; }
}
public static UInt64 Compute(UInt64 seed, byte[] buffer) {
return CalculateHash(seed, buffer, 0, buffer.Length);
}
private static UInt64 CalculateHash(UInt64 seed, byte[] buffer, int start, int size) {
UInt64 crc = seed;
for (int i = start; i < size; i++)
unchecked {
crc = (crc >> 8) ^ table[(buffer[i] ^ crc) & 0xff];
}
return crc;
}
private byte[] UInt64ToBigEndianBytes(UInt64 x) {
return new byte[] {
(byte)((x >> 56) & 0xff),
(byte)((x >> 48) & 0xff),
(byte)((x >> 40) & 0xff),
(byte)((x >> 32) & 0xff),
(byte)((x >> 24) & 0xff),
(byte)((x >> 16) & 0xff),
(byte)((x >> 8) & 0xff),
(byte)(x & 0xff) };
}
}To use this or the CRC-32 class to compute the hash for a file simply:
Crc64 crc64 = new Crc64();
String hash = String.Empty;
using (FileStream fs = File.Open("c:\\myfile.txt", FileMode.Open))
foreach (byte b in crc64.ComputeHash(fs)) hash += b.ToString("x2").ToLower();
Console.WriteLine("CRC-64 is {0}", hash);
Whilst writing this I considered if I should implement some more advanced hashing algorithms missing from .NET like RIPEMD320 only to stumble across The Legion of Bouncy Castles C# Cryptography APIs which also includes generating PKCS #12 files and a whole bunch of encryption algorithms (but nothing as weak as CRC-64 ;-)
[)amien
Dissecting a C# Application – Inside SharpDevelop
This great book shows you the process, thinking and code behind the open-source .NET IDE SharpDevelop that went on to branch into MonoDevelop.
It was not in print for very long but Apress bought Wrox when they closed down and made the book freely available on its site for download in PDF format.
Alas, with their most recent web redesign their free e-books section has disappeared so I am temporarily hosting it here after recommending it to somebody interested in writing their own syntax highlighting editor on the MSDN forums.
Download Dissecting a C# Application – Inside SharpDevelop (Adobe PDF) (3.9MB)
[)amien