T4 template to generate some useful N-Tuple overloads of common System.Reactive extension methods

ObservableExtensions.tt

<#@ template debug="false" hostspecific="false" language="C#" #>
<#@ output extension="Generated.cs" #>
<#@ assembly name="System.Core" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Runtime.Remoting.Messaging" #>
<#@ import namespace="Microsoft.VisualStudio.TextTemplating" #>
using System;
using System.Linq;
using System.Reactive;
 
namespace <#=CallContext.GetData("NamespaceHint")#>
{
    public static partial class ObservableExtensions
    {
<#
for(int i = 1; i < 8; i++)
{
#>
        public static Tuple<<#=Types(i)#>, TOther> Append<<#=Types(i)#>, TOther>(this <#=Container(i)#> s, TOther o)
        {
            return new Tuple<<#=Types(i)#>, TOther>(<#=Values(i)#>, o);
        }

<#
}
for(int i = 1; i < 8; i++)
{
#>
        public static IObservable<Tuple<<#=Types(i)#>, TOther>> CombineLatest<<#=Types(i)#>, TOther>(this IObservable<<#=Container(i)#>> source, IObservable<TOther> other)
        {
            return source.CombineLatest(other, Append);
        }

<#
}
for(int i = 1; i < 8; i++)
{
#>	
        public static IObservable<Tuple<<#=Types(i)#>, TOther>> Zip<<#=Types(i)#>, TOther>(this IObservable<<#=Container(i)#>> source, IObservable<TOther> other)
        {
            return source.Zip(other, Append);
        }

<#
}
#>
    }
}

<#+

public string Container(int i)
{
    return i == 1 ? "T1" : "Tuple<"+Expand(i, "T{0}")+">";
}

public string Values(int i)
{
    return i == 1 ? "s" : Expand(i, "s.Item{0}");
}

public string Types(int length)
{
    return Expand(length, "T{0}");
} 
 

public string Expand(int length, string format)
{
    return string.Join(", ", Enumerable.Range(1, length).Select(x=>string.Format(format, x)));
} 

#>