Interesting / strange code picked up from pluralsight training (functional programming)

[raddevus]

You are exactly correct about the return being the important part because it allows you to chain the methods. In another post I mentioned that you can do a "before and after" type of test which might look like:

Helper.Tee(Helper.Tee(" _ before after _ ", Console.WriteLine)
.ToUpper().Trim()
.Substring(8,6),
Console.WriteLine);

That results in an output like the following:

_ before after _
AFTER

[raddevus]

Yes, it does look that way...and I'm learning this stuff myself. However, I've provided a slightly better example in reply to Sander at: The Weird and The Wonderful[^] That at least makes a bit of sense. :)

[Super Lloyd]

it's cute, you are learning new stuff. that is good. :) The Tee code sample is contrived though, simply because it can be rewritten much more mean and lean like

var value = ...;
action(value)
// ... continue ...

it was, to put it bluntly, grossly over engineered, and should not be done in real work project! :-o However here is something like the given Tee function that could be more useful

public static class Helper
{
public static IEnumerable<T> Tee(this IEnumerable<T> enumerable, Action<T> action)
{
foreach (var e in enumerable)
{
action(e);
yield return e;
}
}
}

A new .NET Serializer All in one Menu-Ribbon Bar Taking over the world since 1371!

[Richard Deeming]

It might help if you gave the method a name! :-D

---

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

[Richard Deeming]

This definitely looks like a case for an extension method[^]. :)

" _ before after _ "
.Tee(Console.WriteLine)
.ToUpper().Trim()
.Substring(8, 6)
.Tee(Console.WriteLine);

---

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

[Super Lloyd]

oops.. corrected! :-\

A new .NET Serializer All in one Menu-Ribbon Bar Taking over the world since 1371!

[raddevus]

Ah, yes, that would be even better. Makes far more sense that way. :thumbsup:

[raddevus]

That was interesting to me so I altered the Tee method to make it an extension method. Simply add the _this_ to the first param T and your code works now.

public static class Helper{
public static T Tee(
this T @inVal,
Action act){
act(@inVal);
return @inVal;
}
}

" _ before after _ "
.Tee(Console.WriteLine)
.ToUpper().Trim()
.Substring(8,6)
.Tee(Console.WriteLine);

[raddevus]

Ohh...look...I've really gone crazy with this now.

public static class Helper{
public static T Tee(
this T @inVal,
Action act){
act(@inVal);
return @inVal;
}

public static Byte\[\] GetBytes( this String @inVal){
	Byte \[\] outBytes = new Byte\[@inVal.Length\];
	int loopCount = 0;
	foreach (Char c in @inVal){
		outBytes\[loopCount\] = Convert.ToByte(c);
		loopCount++;
	}
	return outBytes;
}

public static String DisplayBytes(this byte\[\] inBytes){
	String outVal = String.Empty;
	foreach (Byte b in inBytes){
		outVal += Convert.ToString($"{b} ");
	}
	return outVal;
}

}

Try it like this and you get before and after again:

"What up!"
.Tee(Console.WriteLine)
.GetBytes()
.DisplayBytes()
.Tee(Console.WriteLine);

Output looks like:

What up!
87 104 97 116 32 117 112 33

:cool: Well, it's fun.

[Lost User]

It doesn't copy stdin to stdout. The only thing in common with "tee" is in the amount of parameters.

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

[raddevus]

Yes, you are correct. I think the point that the author/presenter was attempting to make is that you can output the value and continue processing the value as input to yet another function. That's why the author/presenter named the method Tee (which I hadn't seen before). I looked it up and found the associated wiki article and just thought that was an interesting piece of history.

[Lost User]

raddevus wrote:

I think the point that the author/presenter was attempting to make is that you can output the value and continue processing the value as input to yet another function.

Like a decorator..

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

[raddevus]

Eddy Vluggen wrote:

Like a decorator..

cue Madonna

...touched for the very first time...

:laugh: I could not pass that up. Ignoring the bad joke (if possible) I think your point is really interesting, because it is like a decorator. Also, in an effort to completely beat this dead horse, how about the following addition? If, nothing else, the added method has a great name : see SpaceOut.

public static class Helper{
public static T Tee(
this T @inVal,
Action act){
act(@inVal);
return @inVal;
}

public static Byte\[\] GetBytes( this String @inVal){
	Byte \[\] outBytes = new Byte\[@inVal.Length\];
	int loopCount = 0;
	foreach (Char c in @inVal){
		outBytes\[loopCount\] = Convert.ToByte(c);
		loopCount++;
	}
	return outBytes;
}

public static String DisplayBytes(this byte\[\] inBytes){
	String outVal = String.Empty;
	foreach (Byte b in inBytes){
		outVal += Convert.ToString($"{b:D3} ");
	}
	return outVal;
}

public static String SpaceOut(this string @inVal){
	StringBuilder spacedItem = new StringBuilder();

	foreach (Char c in @inVal){
		spacedItem.Append($" {c}    ");
	}
	Console.WriteLine(spacedItem.ToString());
	return @inVal;
}

}

Now you can do this:

"What up!"
.Tee(Console.WriteLine)
.SpaceOut()
.GetBytes()
.DisplayBytes()
.Tee(Console.WriteLine);

And you will get the following:

What up!
W h a t u p !
087 104 097 116 032 117 112 033

Additionally interesting (or not) is that SpaceOut simply passes the input string along with no change since you only want the input to be printed with the extra spaces but don't want the output altered in this case. I got a million of 'em! :laugh:

[Lost User]

:laugh:

raddevus wrote:

I got a million of 'em! :laugh:

Is that due to .NET being functional, or due to OO and your result being an object? :-\

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

[Nelek]

You look like a kid with brand shiny new shoes :rolleyes: :rolleyes: ;P ;P :laugh: :laugh:

M.D.V. ;) If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about? Help me to understand what I'm saying, and I'll explain it better to you Rating helpful answers is nice, but saying thanks can be even nicer.

[Sander Rossel]

Like Richard, I was thinking of an extension method. What you have there is pretty hard to read, took me a while to figure out what it does (due to the nested Tee, which is not a very helpful name either). I'm all for chaining though, that's what LINQ does too (which is pretty functional). Applying functional principles (but remembering C# is not a functional language) really helped me write cleaner and more succinct code. Although not everyone agrees with me, some people prefer their foreach loops and can't read lambda's :sigh: One thing I've learned, and taken to heart, a function has input and predictable output (no side-effects or state!). At some point you're going to have state and output, of course, but that's reserved for special classes. To give an example (from the top of my head, ignore bad practices such as public fields):

public class BadClass
{
public string s;
public void BadClass(string s)
{
this.s = s;
}

public void DoubleString()
{
s = s + s;
}
}

// Usage
var bc = new BadClass("Hello");
bs.DoubleString();
Console.WriteLine(bc.s); // HelloHello

public class GoodClass
{
public void DoubleString(string s)
{
return s + s;
}
}

// Usage
var gc = new GoodClass();
var s = gc.DoubleString("Hello");
Console.WriteLine(s); // HelloHello

It's a bit contrived, but you'd be amazed at how often I've seen the BadClass implementation (equivalent) of this. People just love their state and side effects. But then again, I've worked on old VB applications with old VB programmers... As coincidence would have it Packt offers a free Functional C#[^] eBook today, may be interesting (haven't read it myself).

Best, Sander Continuous Integration, Delivery, and Deployment arrgh.js - Bringing LINQ to JavaScript Object-Oriented Programming in C# Succinctly

[icemanind]

Why is an @ sign being used for @inVal? Aren't those only used for naming a variable after a reserved keyword?

[raddevus]

Nelek wrote:

like a kid with brand shiny new shoes

No, unfortunately I have the same old shoes. But, I did get a haircut recently, that we could talk about if you like. :laugh:

[raddevus]

Eddy Vluggen wrote:

or due to OO and your result being an object?

A valid point. :(( But, blithely I roll on. :laugh: Let's see. what else could I do to a String?... :rolleyes:

[raddevus]

icemanind wrote:

Why is an @ sign being used for @inVal?

I wondered the same thing. This was the choice of the author/presenter and I hadn't seen that before either. He actually had his param named @this so it was even worse to me in that way. I didn't know C# allowed a var to be named with a beginning @ sign either, but apparently you can.