Trigger function(s) based upon Boolean result without using the iF word

Question

if(someBoolTest()) dothis()
else dothat();

or just

if(someBoolTest()) dothis();

Wouldn't it be nice to do something like:

someBoolTest() => {dothis(),dothat()}

or

someBoolTest() => dothis()

Is this done in other languages? How do we do this in C#? (I don't think we can, so then why not?)

EDIT: I am aware of ternary ops, but that doesn't make it look any better. Would be nice to do this with some form of lambda with delegates..

You need to [read this](http://stackoverflow.com/a/4966409/2589202) — crthompson, Apr 23 '15 at 22:57
I'm really unclear of the point of this question. Is this just a rant on how you aren't happy that C# isn't a functional language? — Claies, Apr 23 '15 at 23:12
yes, it is partially a rant. but at the same time, it asks the question of why can't C# have this language extension..| But I am happy with C#, it is what I use every day.. — LastTribunal, Apr 23 '15 at 23:14

Yuval Itzchakov · Answer 1 · 2015-04-23T23:07:13.707

4

How do we do this in C#?

Using the if-else clause, just as you did in your example.

You could be creative and create something of this sort:

(SomeBoolTest() ? (Action)DoThis : DoThat)();

But that is terribly unreadable code, don't do that.

edited Apr 23 '15 at 23:07

answered Apr 23 '15 at 22:59

Yuval Itzchakov

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I'm sure functional languages have a different way of doing `if-else` branching. Still, I don't see anything wrong with them. – Yuval Itzchakov Apr 23 '15 at 23:02
@LastTribunal What are dirty word? – Black Frog Apr 23 '15 at 23:03
@Black He's referring to `if-else` – Yuval Itzchakov Apr 23 '15 at 23:03
I just wanted to be clear. Because `if-else` is one of the basic building blocks of programming. And the con with using `?: Operator` is that is doesn't do [Short-circuit evaluation](http://en.wikipedia.org/wiki/Short-circuit_evaluation). – Black Frog Apr 23 '15 at 23:07
If statements are the building blocks of spaghetti code. All efforts in OOP and Design Patterns were basically intended to address the obscenity of "iF" words.. – LastTribunal Apr 23 '15 at 23:12
1

Can you actually articulate what you find offensive about the if-else construct? – Blorgbeard Apr 23 '15 at 23:49
@BlackFrog the conditional (`?:`) operator does short-circuit. – Blorgbeard Apr 24 '15 at 00:01

score 2 · Answer 2 · answered Apr 23 '15 at 23:19

2

You can, but should not, do something that resembles the syntax that you mentioned, by doing something stupid like writing an extension method over a bool type, as shown in the below example:

public static class UselessExtensions
{
    public static void WhenTrue(this bool evaluatedPredicate, Action whenTrue)
    {
        if (evaluatedPredicate)
            whenTrue();
    }
}

public static class TryingUselessExtensions
{
    public static bool SomeBoolTest()
    {
        return true;
    }

    public static void DoIt()
    {
        SomeBoolTest().WhenTrue(() => Console.WriteLine(true));
    }
}

answered Apr 23 '15 at 23:19

Alex

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It defers ifs to a lower level, which is an improvement – LastTribunal Apr 24 '15 at 00:18
@Claies As you can see, the answer specifically states "something that resembles the **syntax** ...", its purpose is not to get rid of the if statement. – Alex Apr 24 '15 at 00:19
1

true, but in other comments the poster has suggested the reason for the question in the first place is their dislike of `if-else`, referring to it as "these dirty words, will be removed from all evolved languages". It isn't a sensible statement, but the poster has made it clear they want an alternative to `if-else`, not just syntax to hide it (unless I'm way off). – Claies Apr 24 '15 at 00:25

score 0 · Answer 3 · answered Apr 23 '15 at 23:03

0

I believe ternary operators are what you're looking for:

variable = condition ? value_if_true : value_if_false

So, for example you want an int to equal 0 if your condition is met, and 3 if it is not:

int this = 500;
int that = 700;
int n = (this==that) ? 0 : 3;

In this case n would be assigned the value of 3! There's a good wikipedia page on this, head on over and give it a look :)

Wikipedia page on ternary operators

answered Apr 23 '15 at 23:03

Ola Næss Kaldestad

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This approach is useful when you want a conditional expression to return a value and each operand is a function that returns a value. However, the question is about how to conditionally execute a pair of functions where neither returns a value. – DavidRR Sep 29 '15 at 14:06

Winky2222 · Answer 4 · 2015-04-23T23:01:33.700

-1

You do it like this

    bool myBool = true;
    bool newBool;
    public void Main()
    {
        MyFunction( newBool = (aFunctionThatReturnsABool == true) ? true: false);
    }

    public void MyFunction (bool aBool)
    {
        // stuff based on the bool
    }

But what are you actually trying to do?

edited Apr 23 '15 at 23:01

answered Apr 23 '15 at 22:47

Winky2222

46
7

need to call methods, not set variables – LastTribunal Apr 23 '15 at 22:48
`(aFunctionThatReturnsABool == true) ? true: false` is exactly equivalent to `aFunctionThatReturnsABool`, btw. – Blorgbeard Apr 23 '15 at 23:51

Trigger function(s) based upon Boolean result without using the iF word

4 Answers4