확장 메서드를 사용하여 리팩터링

업데이트: November 2007

이 예제는 확장 메서드로 구현된 순수 함수를 사용하여 문자열의 연결을 리팩터링하는 방법으로 이전 예제인 단락의 텍스트 검색을 기반으로 작성되었습니다.

이전 예제에서는 Aggregate 표준 쿼리 연산자를 사용하여 여러 문자열을 한 문자열로 연결합니다. 그러나 생성되는 쿼리가 더 작고 간단하기 때문에 이 작업을 수행하는 확장 메서드를 작성하는 것이 간편합니다.

예제

이 예제에서는 WordprocessingML 문서를 처리하여 단락, 각 단락의 스타일 및 각 단락의 텍스트를 검색합니다. 이 예제는 이 자습서의 이전 예제를 기반으로 합니다.

이 예제에는 StringConcatenate 메서드의 오버로드가 여러 개 포함되어 있습니다.

소스 Office Open XML 문서 만들기에서 이 예제의 소스 문서를 만드는 지침을 찾을 수 있습니다.

이 예제에서는 WindowsBase 어셈블리의 클래스를 사용하고 System.IO.Packaging 네임스페이스의 형식을 사용합니다.

public static class LocalExtensions
{
    public static string StringConcatenate(this IEnumerable<string> source)
    {
        StringBuilder sb = new StringBuilder();
        foreach (string s in source)
            sb.Append(s);
        return sb.ToString();
    }

    public static string StringConcatenate<T>(this IEnumerable<T> source,
        Func<T, string> func)
    {
        StringBuilder sb = new StringBuilder();
        foreach (T item in source)
            sb.Append(func(item));
        return sb.ToString();
    }

    public static string StringConcatenate(this IEnumerable<string> source, string separator)
    {
        StringBuilder sb = new StringBuilder();
        foreach (string s in source)
            sb.Append(s).Append(separator);
        return sb.ToString();
    }

    public static string StringConcatenate<T>(this IEnumerable<T> source,
        Func<T, string> func, string separator)
    {
        StringBuilder sb = new StringBuilder();
        foreach (T item in source)
            sb.Append(func(item)).Append(separator);
        return sb.ToString();
    }
}

<System.Runtime.CompilerServices.Extension()> _
Public Function StringConcatenate(ByVal source As IEnumerable(Of String)) As String
    Dim sb As StringBuilder = New StringBuilder()
    For Each s As String In source
        sb.Append(s)
    Next
    Return sb.ToString()
End Function

<System.Runtime.CompilerServices.Extension()> _
Public Function StringConcatenate(Of T)(ByVal source As IEnumerable(Of T), _
ByVal func As Func(Of T, String)) As String
    Dim sb As StringBuilder = New StringBuilder()
    For Each item As T In source
        sb.Append(func(item))
    Next
    Return sb.ToString()
End Function

<System.Runtime.CompilerServices.Extension()> _
Public Function StringConcatenate(Of T)(ByVal source As IEnumerable(Of T), _
ByVal separator As String) As String
    Dim sb As StringBuilder = New StringBuilder()
    For Each s As T In source
        sb.Append(s).Append(separator)
    Next
    Return sb.ToString()
End Function

<System.Runtime.CompilerServices.Extension()> _
Public Function StringConcatenate(Of T)(ByVal source As IEnumerable(Of T), _
ByVal func As Func(Of T, String), ByVal separator As String) As String
    Dim sb As StringBuilder = New StringBuilder()
    For Each item As T In source
        sb.Append(func(item)).Append(separator)
    Next
    Return sb.ToString()
End Function

예제

StringConcatenate 메서드의 오버로드는 네 가지가 있습니다. 한 오버로드는 문자열의 컬렉션을 가져와서 단일 문자열을 반환합니다. 다른 오버로드는 원하는 형식의 컬렉션과 컬렉션의 singleton에서 문자열로 프로젝션하는 대리자를 사용할 수 있습니다. 나머지 두 오버로드는 구분 기호 문자열을 지정할 수 있도록 합니다.

다음 코드에서는 네 오버로드를 모두 사용합니다.

string[] numbers = { "one", "two", "three" };

Console.WriteLine("{0}", numbers.StringConcatenate());
Console.WriteLine("{0}", numbers.StringConcatenate(":"));

int[] intNumbers = { 1, 2, 3 };
Console.WriteLine("{0}", intNumbers.StringConcatenate(i => i.ToString()));
Console.WriteLine("{0}", intNumbers.StringConcatenate(i => i.ToString(), ":"));

Dim numbers As String() = {"one", "two", "three"}

Console.WriteLine("{0}", numbers.StringConcatenate())
Console.WriteLine("{0}", numbers.StringConcatenate(":"))

Dim intNumbers As Integer() = {1, 2, 3}
Console.WriteLine("{0}", intNumbers.StringConcatenate(Function(i) i.ToString()))
Console.WriteLine("{0}", intNumbers.StringConcatenate(Function(i) i.ToString(), ":"))

이 예제의 결과는 다음과 같습니다.

onetwothree
one:two:three:
123
1:2:3:

예제

이제 새 확장 메서드를 활용하기 위해 예제를 수정할 수 있습니다.

public static class LocalExtensions
{
    public static string StringConcatenate(this IEnumerable<string> source)
    {
        StringBuilder sb = new StringBuilder();
        foreach (string s in source)
            sb.Append(s);
        return sb.ToString();
    }

    public static string StringConcatenate<T>(this IEnumerable<T> source,
        Func<T, string> func)
    {
        StringBuilder sb = new StringBuilder();
        foreach (T item in source)
            sb.Append(func(item));
        return sb.ToString();
    }

    public static string StringConcatenate(this IEnumerable<string> source, string separator)
    {
        StringBuilder sb = new StringBuilder();
        foreach (string s in source)
            sb.Append(s).Append(separator);
        return sb.ToString();
    }

    public static string StringConcatenate<T>(this IEnumerable<T> source,
        Func<T, string> func, string separator)
    {
        StringBuilder sb = new StringBuilder();
        foreach (T item in source)
            sb.Append(func(item)).Append(separator);
        return sb.ToString();
    }
}

class Program
{
    static void Main(string[] args)
    {
        const string fileName = "SampleDoc.docx";

        const string documentRelationshipType =
          "https://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument";
        const string stylesRelationshipType =
          "https://schemas.openxmlformats.org/officeDocument/2006/relationships/styles";
        const string wordmlNamespace =
          "https://schemas.openxmlformats.org/wordprocessingml/2006/main";
        XNamespace w = wordmlNamespace;

        XDocument xDoc = null;
        XDocument styleDoc = null;

        using (Package wdPackage = Package.Open(fileName, FileMode.Open, FileAccess.Read))
        {
            PackageRelationship docPackageRelationship =
              wdPackage.GetRelationshipsByType(documentRelationshipType).FirstOrDefault();
            if (docPackageRelationship != null)
            {
                Uri documentUri = PackUriHelper.ResolvePartUri(new Uri("/", UriKind.Relative),
                  docPackageRelationship.TargetUri);
                PackagePart documentPart = wdPackage.GetPart(documentUri);

                //  Load the document XML in the part into an XDocument instance.
                xDoc = XDocument.Load(XmlReader.Create(documentPart.GetStream()));

                //  Find the styles part. There will only be one.
                PackageRelationship styleRelation =
                  documentPart.GetRelationshipsByType(stylesRelationshipType).FirstOrDefault();
                if (styleRelation != null)
                {
                    Uri styleUri =
                      PackUriHelper.ResolvePartUri(documentUri, styleRelation.TargetUri);
                    PackagePart stylePart = wdPackage.GetPart(styleUri);

                    //  Load the style XML in the part into an XDocument instance.
                    styleDoc = XDocument.Load(XmlReader.Create(stylePart.GetStream()));
                }
            }
        }

        string defaultStyle =
            (string)(
                from style in styleDoc.Root.Elements(w + "style")
                where (string)style.Attribute(w + "type") == "paragraph" &&
                      (string)style.Attribute(w + "default") == "1"
                select style
            ).First().Attribute(w + "styleId");

        // Find all paragraphs in the document.
        var paragraphs =
            from para in xDoc
                         .Root
                         .Element(w + "body")
                         .Descendants(w + "p")
            let styleNode = para
                            .Elements(w + "pPr")
                            .Elements(w + "pStyle")
                            .FirstOrDefault()
            select new
            {
                ParagraphNode = para,
                StyleName = styleNode != null ?
                    (string)styleNode.Attribute(w + "val") :
                    defaultStyle
            };

        // Retrieve the text of each paragraph.
        var paraWithText =
            from para in paragraphs
            select new
            {
                ParagraphNode = para.ParagraphNode,
                StyleName = para.StyleName,
                Text = para
                       .ParagraphNode
                       .Elements(w + "r")
                       .Elements(w + "t")
                       .StringConcatenate(e => (string)e)
            };

        foreach (var p in paraWithText)
            Console.WriteLine("StyleName:{0} >{1}<", p.StyleName, p.Text);
    }
}

Imports <xmlns:w="https://schemas.openxmlformats.org/wordprocessingml/2006/main">

Module Module1
    <System.Runtime.CompilerServices.Extension()> _
    Public Function StringConcatenate(ByVal source As IEnumerable(Of String)) As String
        Dim sb As StringBuilder = New StringBuilder()
        For Each s As String In source
            sb.Append(s)
        Next
        Return sb.ToString()
    End Function

    <System.Runtime.CompilerServices.Extension()> _
    Public Function StringConcatenate(Of T)(ByVal source As IEnumerable(Of T), _
    ByVal func As Func(Of T, String)) As String
        Dim sb As StringBuilder = New StringBuilder()
        For Each item As T In source
            sb.Append(func(item))
        Next
        Return sb.ToString()
    End Function

    <System.Runtime.CompilerServices.Extension()> _
    Public Function StringConcatenate(Of T)(ByVal source As IEnumerable(Of T), _
    ByVal separator As String) As String
        Dim sb As StringBuilder = New StringBuilder()
        For Each s As T In source
            sb.Append(s).Append(separator)
        Next
        Return sb.ToString()
    End Function

    <System.Runtime.CompilerServices.Extension()> _
    Public Function StringConcatenate(Of T)(ByVal source As IEnumerable(Of T), _
    ByVal func As Func(Of T, String), ByVal separator As String) As String
        Dim sb As StringBuilder = New StringBuilder()
        For Each item As T In source
            sb.Append(func(item)).Append(separator)
        Next
        Return sb.ToString()
    End Function

    ' Following function is required because VB does not support short circuit evaluation
    Private Function GetStyleOfParagraph(ByVal styleNode As XElement, _
                                         ByVal defaultStyle As String) As String
        If (styleNode Is Nothing) Then
            Return defaultStyle
        Else
            Return styleNode.@w:val
        End If
    End Function

    Sub Main()
        Dim fileName = "SampleDoc.docx"

        Dim documentRelationshipType = _
          "https://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument"
        Dim stylesRelationshipType = _
          "https://schemas.openxmlformats.org/officeDocument/2006/relationships/styles"
        Dim wordmlNamespace = _
          "https://schemas.openxmlformats.org/wordprocessingml/2006/main"

        Dim xDoc As XDocument = Nothing
        Dim styleDoc As XDocument = Nothing
        Using wdPackage As Package = Package.Open(fileName, FileMode.Open, FileAccess.Read)
            Dim docPackageRelationship As PackageRelationship = _
              wdPackage.GetRelationshipsByType(documentRelationshipType).FirstOrDefault()
            If (docPackageRelationship IsNot Nothing) Then
                Dim documentUri As Uri = PackUriHelper.ResolvePartUri(New Uri("/", UriKind.Relative), _
                  docPackageRelationship.TargetUri)
                Dim documentPart As PackagePart = wdPackage.GetPart(documentUri)

                '  Load the document XML in the part into an XDocument instance.
                xDoc = XDocument.Load(XmlReader.Create(documentPart.GetStream()))

                '  Find the styles part. There will only be one.
                Dim styleRelation As PackageRelationship = _
                  documentPart.GetRelationshipsByType(stylesRelationshipType).FirstOrDefault()
                If (styleRelation IsNot Nothing) Then
                    Dim styleUri As Uri = _
                      PackUriHelper.ResolvePartUri(documentUri, styleRelation.TargetUri)
                    Dim stylePart As PackagePart = wdPackage.GetPart(styleUri)

                    '  Load the style XML in the part into an XDocument instance.
                    styleDoc = XDocument.Load(XmlReader.Create(stylePart.GetStream()))
                End If
            End If
        End Using

        Dim defaultStyle As String = _
            ( _
                From style In styleDoc.Root.<w:style> _
                Where style.@w:type = "paragraph" And _
                      style.@w:default = "1" _
                Select style _
            ).First().@w:styleId

        ' Find all paragraphs in the document.
        Dim paragraphs = _
            From para In xDoc.Root.<w:body>...<w:p> _
        Let styleNode As XElement = para.<w:pPr>.<w:pStyle>.FirstOrDefault _
        Select New With { _
            .ParagraphNode = para, _
            .StyleName = GetStyleOfParagraph(styleNode, defaultStyle) _
        }

        ' Retrieve the text of each paragraph.
        Dim paraWithText = _
            From para In paragraphs _
            Select New With { _
                .ParagraphNode = para.ParagraphNode, _
                .StyleName = para.StyleName, _
                .Text = para.ParagraphNode.<w:r>.<w:t>.StringConcatenate(Function(e) CStr(e)) _
            }

        For Each p In paraWithText
            Console.WriteLine("StyleName:{0} >{1}<", p.StyleName, p.Text)
        Next

    End Sub
End Module

소스 Office Open XML 문서 만들기에서 설명하는 문서에 적용할 때 이 예제의 결과는 다음과 같습니다.

StyleName:Heading1 >Parsing WordprocessingML with LINQ to XML<
StyleName:Normal ><
StyleName:Normal >The following example prints to the console.<
StyleName:Normal ><
StyleName:Code >using System;<
StyleName:Code ><
StyleName:Code >class Program {<
StyleName:Code >    public static void (string[] args) {<
StyleName:Code >        Console.WriteLine("Hello World");<
StyleName:Code >    }<
StyleName:Code >}<
StyleName:Normal ><
StyleName:Normal >This example produces the following output:<
StyleName:Normal ><
StyleName:Code >Hello World<

이 리팩터링은 순수 함수로의 리팩터링에 대한 변형입니다. 다음 항목에서는 순수 함수로의 팩터링 개념에 대해 자세히 소개합니다.

다음 단계

다음 예제에서는 순수 함수를 사용하여 다른 방식으로 이 코드를 리팩터링하는 방법을 보여 줍니다.

• 순수 함수를 사용하여 리팩터링

참고 항목

개념

자습서: WordprocessingML 문서에서 내용 조작

순수 함수로 리팩터링