The StringBuilder extension in C # supports the chain method,

The StringBuilder extension in C # supports the chain method,

 

This article expands StringBuilder to support the chained method.

Here is a method for generating select elements based on a set of key values.

 

private static string BuilderSelectBox(IDictionary<int, string> options, string id, bool includeUnknown){    var html = new StringBuilder();    html.AppendFormat("<select id=\"{0}\" name=\"{0}\">", id);    html.AppendLine();        if(includeUnknown)    {        html.AppendLine("\t<option>Unknown</option>");    }        foreach(var opt in options)    {        html.AppendFormat("\t<option value=\"{0}\">{1}</option>", opt.Key, opt.Value);        html.AppendLine();    }        html.AppendLine("</select>");        return html.ToString();}

 

Above,

Html. AppendFormat ("<select id = \" {0} \ "name = \" {0} \ ">", id );
Html. AppendLine ();

These two statements can be encapsulated to extend StringBuilder.


Change

public static class StringBuilderExtensions{    public static StringBuilder AppendFormattedLine(this StringBuilder @this, string format, prams object[] args) => @this.AppendFormat(format, args).AppendLine();}private static string BuilderSelectBox(IDictionary<int, string> options, string id, bool includeUnknown){    var html = new StringBuilder()        .AppendFormattedLine("<select id=\"{0}\" name=\"{0}\">", id);        if(includeUnknown)    {        html.AppendLine("\t<option>Unknown</option>");    }        foreach(var opt in options)    {        html.AppendFormattedLine("\t<option value=\"{0}\">{1}</option>", opt.Key, opt.Value);        html.AppendLine();    }        html.AppendLine("</select>");        return html.ToString();}

 

Above,

If (includeUnknown)
{
Html. AppendLine ("\ t <option> Unknown </option> ");
}

The preceding statement can be encapsulated to extend StringBuilder.

 

public static class StringBuilderExtensions{    public static StringBuilder AppendFormattedLine(this StringBuilder @this, string format, prams object[] args) => @this.AppendFormat(format, args).AppendLine();        public static StringBuilder AppendLineWhen(this StringBuilder @this, Func<bool> predicate, string value) =>    predicate()         ? @this.AppendLine(value)        : @this;    }private static string BuilderSelectBox(IDictionary<int, string> options, string id, bool includeUnknown){    var html = new StringBuilder()        .AppendFormattedLine("<select id=\"{0}\" name=\"{0}\">", id)        .AppendLineWhen(() => includeUnknown, "\t<option>Unknown</option>");        foreach(var opt in options)    {        html.AppendFormattedLine("\t<option value=\"{0}\">{1}</option>", opt.Key, opt.Value);    }        html.AppendLine("</select>");        return html.ToString();}

 

Or

 

public static class StringBuilderExtensions{    public static StringBuilder AppendFormattedLine(this StringBuilder @this, string format, prams object[] args) => @this.AppendFormat(format, args).AppendLine();        public static StringBuilder AppendLineWhen(this StringBuilder @this, Func<bool> predicate, string value) =>    predicate()         ? @this.AppendLine(value)        : @this;            public static StringBuilder AppendWhen(this StringBuilder @this, Func<bool> predicate, Func<StringBuilder, StringBuilder> fn) =>    predicate()        ? fn(@this)        : @this;    }private static string BuilderSelectBox(IDictionary<int, string> options, string id, bool includeUnknown){    var html = new StringBuilder()        .AppendFormattedLine("<select id=\"{0}\" name=\"{0}\">", id)        .AppendWhen(            () => includeUnknown,            sb => sb.AppendLine("\t<option>Unknown</option>")        );        foreach(var opt in options)    {        html.AppendFormattedLine("\t<option value=\"{0}\">{1}</option>", opt.Key, opt.Value);    }        html.AppendLine("</select>");        return html.ToString();}

 

Above,

Foreach (var opt in options)
{
Html. AppendFormattedLine ("\ t <option value = \" {0} \ ">{1} </option>", opt. Key, opt. Value );
}

Encapsulate traversal statements, expand StringBuilder, and finally:

 

public static class StringBuilderExtensions{    public static StringBuilder AppendFormattedLine(this StringBuilder @this, string format, prams object[] args) => @this.AppendFormat(format, args).AppendLine();        public static StringBuilder AppendLineWhen(this StringBuilder @this, Func<bool> predicate, string value) =>    predicate()         ? @this.AppendLine(value)        : @this;            public static StringBuilder AppendWhen(this StringBuilder @this, Func<bool> predicate, Func<StringBuilder, StringBuilder> fn) =>    predicate()        ? fn(@this)        : @this;            public static StringBuilder AppendSequence<T>(this StringBuilder @this, IEnumerable<T> seq, Func<StringBuilder, T, StringBuilder> fn) => seq.Aggregate(@this, fn);    }private static string BuilderSelectBox(IDictionary<int, string> options, string id, bool includeUnknown){    var html = new StringBuilder()        .AppendFormattedLine("<select id=\"{0}\" name=\"{0}\">", id)        .AppendWhen(            () => includeUnknown,            sb => sb.AppendLine("\t<option>Unknown</option>")        )        .AppendSequence(options, (sb, opt) => sb.AppendFormattedLine("\t<option value=\"{0}\">{1}</option>", opt.Key, opt.Value))        .AppendLine("</select>")        .ToString();}