Ian Griffiths idg10

## ParseFile.cs
// Excerpt from https://blogs.msdn.microsoft.com/seteplia/2018/09/05/combining-iterator-blocks-and-async-methods-in-c/

public static IEnumerable<Task<int>> ParseFile(string path)
{
    if (string.IsNullOrEmpty(path)) { throw new ArgumentNullException(nameof(path)); }

    // OpenWithRetryPolicyAsync uses RetryPolicy to try to open the file more than once.
    // The method throws FileNotFoundException if the file does not exists.
    using (var file = OpenWithRetryPolicyAsync(path).Result)
    {

## ParseFile-declaration.cs
public static IEnumerable<Task<int>> ParseFile(string path)

## ParseFileUseFirst.cs
Task<int> firstTask = ParseFile(path).First();

## ParseFileUseSecond.cs
// Never do this!
Task<int> firstTask = ParseFile(path).Skip(1).First();

## FuncDeferralResourceMishandling.cs
// This doesn't work.
public static Func<string> GetContentGetter(string configPath)
{
    using (var reader = new StreamReader(configPath))
    {
        return () => reader.ReadToEnd();
    }
}

## TaskDeferralResourceMishandling.cs
// This doesn't work.
public static Task<string> GetContentAsync(string configPath)
{
    using (var reader = new StreamReader(configPath))
    {
        return reader.ReadToEndAsync();
    }
}

## TaskDeferralFixed.cs
public static async Task<string> GetContentAsync(string configPath)
{
    using (var reader = new StreamReader(configPath))
    {
        return await reader.ReadToEndAsync();
    }
}

## EnumerableTaskDeferralResourceMishandling.cs
// This won't work
public static IEnumerable<Task<int>> ParseFile(string path)
{
    using (var reader = new StreamReader(path))
    {
        while (!reader.EndOfStream)
        {
            yield return ReadAndParseAsync(reader);
        }
    }

## EnumerableTaskDeferralResourceHandlingFixed.cs
public static IEnumerable<Task<int>> ParseFile(string path)
{
    using (var reader = new StreamReader(path))
    {
        while (!reader.EndOfStream)
        {
            Task<int> readLineTask = null;
            try
            {
                readLineTask = ReadAndParseAsync(reader);

## FunctionSignatureWithOutParameter.cs
public static bool Read(int[] buffer, out int bytesRead)
	// Excerpt from https://blogs.msdn.microsoft.com/seteplia/2018/09/05/combining-iterator-blocks-and-async-methods-in-c/

	public static IEnumerable<Task<int>> ParseFile(string path)
	{
	if (string.IsNullOrEmpty(path)) { throw new ArgumentNullException(nameof(path)); }

	// OpenWithRetryPolicyAsync uses RetryPolicy to try to open the file more than once.
	// The method throws FileNotFoundException if the file does not exists.
	using (var file = OpenWithRetryPolicyAsync(path).Result)
	{
	// Never do this!
	Task<int> firstTask = ParseFile(path).Skip(1).First();
	// This doesn't work.
	public static Func<string> GetContentGetter(string configPath)
	{
	using (var reader = new StreamReader(configPath))
	{
	return () => reader.ReadToEnd();
	}
	}
	// This doesn't work.
	public static Task<string> GetContentAsync(string configPath)
	{
	using (var reader = new StreamReader(configPath))
	{
	return reader.ReadToEndAsync();
	}
	}
	public static async Task<string> GetContentAsync(string configPath)
	{
	using (var reader = new StreamReader(configPath))
	{
	return await reader.ReadToEndAsync();
	}
	}
	// This won't work
	public static IEnumerable<Task<int>> ParseFile(string path)
	{
	using (var reader = new StreamReader(path))
	{
	while (!reader.EndOfStream)
	{
	yield return ReadAndParseAsync(reader);
	}
	}