Category Archives: Short Walks

Short Walks – Using CompilerService Arguments in an Interface

Until today, I thought that the following code would work:

class Program
{
    static void Main(string[] args)
    {
        ITest test = new Test();
        test.Log("testing");
        Console.ReadLine();
    }
}
 
interface ITest
{
    void Log(string text, string function = "");
}
 
class Test : ITest
{
    public void Log(string text, [CallerMemberName] string function = "")
    {
        Console.WriteLine($"{function} : text");
    }
}

And, by work, I mean output something along the lines of:

Main : testing

However; it actually outputs:

: testing

CompilerServiceAttributes need to be on the Interface, and not on the implementation

class Program
{
    static void Main(string[] args)
    {
        ITest test = new Test();
        test.Log("testing");
        Console.ReadLine();
    }
}
 
interface ITest
{
    void Log(string text, [CallerMemberName] string function = "");
}
 
class Test : ITest
{
    public void Log(string text, string function = "")
    {
        Console.WriteLine($"{function} : text");
    }
}

Why?

When you think about it, it does kind of make sense. Because you’re calling against the interface, the compiler injected value needs to be there; if you took the interface out of the equation, then the attribute needs to be on the class.

You live and learn!

Short Walks – Error: could not find dependent assembly

Error: could not find dependent assembly ‘System.Runtime, Version=4.1.1’

This error can occur when you have conflicting versions of a system (or any) assembly. The following is a .Net Framework feature that will redirect the assemblies to be the same, and thereby resolve the conflict:

      <dependentAssembly>
        <assemblyIdentity name="System.Reflection" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.1.1.0" newVersion="4.3.0" />
      </dependentAssembly>

Short Walks – Whatever happened to WinGrep?

Unix users will know the joy of being able to use grep to simply find text somewhere in a file in a directory, or its sub-directories. In Windows, we used to have a tool called WinGrep; however, I tried to navigate there today, and it had been taken down.

There were problems with WinGrep – it was slow, and cumbersome; but it did do what it said on the tin. Now that it’s gone, what’s to replace it?

Fortunately, when I had a look around, I found a nice little tool in powershell called findstr. You can use it like so:

 findstr /spinm /c:"mystring"

To find out what /spinm does, type:

findstr /?

FINDSTR [/B] [/E] [/L] [/R] [/S] [/I] [/X] [/V] [/N] [/M] [/O] [/P] [/F:file]
[/C:string] [/G:file] [/D:dir list] [/A:color attributes] [/OFF[LINE]]
strings [[drive:][path]filename[ …]]

/B Matches pattern if at the beginning of a line.
/E Matches pattern if at the end of a line.
/L Uses search strings literally.
/R Uses search strings as regular expressions.
/S Searches for matching files in the current directory and all
subdirectories.
/I Specifies that the search is not to be case-sensitive.
/X Prints lines that match exactly.
/V Prints only lines that do not contain a match.
/N Prints the line number before each line that matches.
/M Prints only the filename if a file contains a match.
/O Prints character offset before each matching line.
/P Skip files with non-printable characters.
/OFF[LINE] Do not skip files with offline attribute set.
/A:attr Specifies color attribute with two hex digits. See “color /?”
/F:file Reads file list from the specified file(/ stands for console).
/C:string Uses specified string as a literal search string.
/G:file Gets search strings from the specified file(/ stands for console).
/D:dir Search a semicolon delimited list of directories
strings Text to be searched for.
[drive:][path]filename
Specifies a file or files to search.

Use spaces to separate multiple search strings unless the argument is prefixed
with /C. For example, ‘FINDSTR “hello there” x.y’ searches for “hello” or
“there” in file x.y. ‘FINDSTR /C:”hello there” x.y’ searches for
“hello there” in file x.y.

Regular expression quick reference:
. Wildcard: any character
* Repeat: zero or more occurrences of previous character or class
^ Line position: beginning of line
$ Line position: end of line
[class] Character class: any one character in set
[^class] Inverse class: any one character not in set
[x-y] Range: any characters within the specified range
\x Escape: literal use of metacharacter x
\ Word position: end of word

Or follow the link at the bottom.

References

https://technet.microsoft.com/en-us/library/cc732459(v=ws.11).aspx