Comma operator in C# (warning: caffeine-overdose-induced FUBAR code inside) | The Coffeehouse

contextfree

I've always found the lack of a comma operator irritating, but I recently realized I can simulate one, or at least its most common use (and in general put statement blocks wherever single statements or expressions are expected) by (ab)using the lambda syntax like so:

for((()=>{int i = 1; int j = 1})(); j < 10000; (()=>{i = j; j = i + j})()) {
   Console.WriteLine(i.ToString());
}

what do you think, sirs? if you were my manager, would you have me lynched if you found the above in my code?

PaoloM
Hypermediocrity

if you were my manager, would you have me lynched if you found the above in my code?

Probably Smiley

If there is another way to accomplish what you need, you should always strive for readability and ease of maintenance.

Blue Ink
C you

Lynched? No. I'm against unnecessary violence, especially when a fellow programmer is involved. But I wouldn't rule out some tarring and feathering. Smiley

1) I cannot get your code compiled on my machine, and I'm extremely puzzled by the notion of variables declared in the body of a lambda expression being in scope later...

2) The only scenario in which I ever found the comma operator useful is the for loop and given that C# already allows commas there, I don't see the need of complicating the code (technically, according to the C# specs, commas in a for are separators, not operators, but it amounts pretty much to the same thing)

contextfree

In reply to Blue Ink

#Oct 17th @ 7:27 PM

ahaha, serves me right for not actually trying it. no, it doesn't work. and, as you mentioned, the scoping doesn't make sense, among other things. in my defense, I had three cups of coffee immediately before posting that.

contextfree

In reply to contextfree

#Oct 17th @ 7:51 PM

This, however, does work:

            int i = 0; int j = 0;
            for (((Action)(() => { i = 1; j = 1; }))(); j < 10000; (((Action)(() => { int k = i; i = j; j = i + k; })))())
            {
                Console.WriteLine(i.ToString());
            }

Isn't it beautiful?

CannotResolveSymbol
{insert caption here}

In reply to contextfree

#Oct 17th @ 8:02 PM

No, not really.

I can't tell what that does at a glance.

contextfree

In reply to CannotResolveSymbol

#Oct 17th @ 8:07 PM

Whose fault is that, yours or mine? Soon all code will be written this way. Those who cannot adapt will be left in the dust. Those who can evolve, will become so much in tune with the code that they won't even need to glance at it: the mere existence of the code on a hard disk or in memory on any computer anywhere will be sufficient to instantaneously call into being a complete understanding of its effects and all its ramifications in their mind. History is on our side, we will bury you!

CannotResolveSymbol
{insert caption here}

In reply to contextfree

#Oct 17th @ 8:20 PM

Note to self: caffeine and lambda expressions don't mix Tongue Out

Minh
WOOH! WOOH!

In reply to contextfree

#Oct 17th @ 8:02 PM

It's ugly as sin, especially compared to

int i = 1; j = 1;

do

{

Console.WriteLine(i);

int k = i;

i = j;

j = i + k;

}

while (j < 10000);

BTW, if I were your manager, and found this in your code, we're having words...

Sven Groot
My name has 9 letters. Coincidence? I think not...

I find this discussion rather baffling.

for( int i = 1, j = 1; j < 10000; i = j, j = i + j )
{
    Console.WriteLine(i);
}

This works fine in C#. So what is the OP's problem?

Dr Herbie
Horses for courses

In reply to Sven Groot

#Oct 17th @ 10:53 PM

"So what is the OP's problem?"

Too much caffeine and "lambda-itis". Tongue Out

Herbie

contextfree

In reply to Sven Groot

#Oct 17th @ 10:53 PM

whoa -- I didn't even know that. I guess the first time I wanted to do a comma in C#, back when I was new to the language and still transitioning from C, I must've done a search somewhere on "comma operator", read that it didn't support it, and never bothered to actually try it. apparently it supports comma-separated statements in for loops, it just treats them as a special syntactic case rather than a use of a general operator.

ok, this thread has been a total fail for me all around Embarassed

Dr Herbie
Horses for courses

In reply to contextfree

#Oct 18th @ 12:09 AM

Well, in it's any consolation, you go up in my estimation for recognising your own fail.

Herbie

LeoDavidson

Someone should make a version of C++ that removes the comma operator (except in for statements) or at least issues a warning when it's used.

Sven Groot
My name has 9 letters. Coincidence? I think not...

In reply to LeoDavidson

#Oct 18th @ 4:04 AM

Or at least removes the ability to overload that operator, because that's a bundle of fun when someone does that. Smiley

exoteric
I : Next<I>

More fun. Factor out the "doubles" loop and use side-effecting LINQ expressions for console output

1.Doubles().To(10000).Out().Do();

Wink

Dodo
I'm your creativity creator™ :)

In reply to contextfree

#Oct 17th @ 8:02 PM

I find it to be rather questionable why you would want to do that. Everything in one line? Bad, very bad. Except if your compiler uses fewer assembly instructions or allocates less memory, there's no point in doing that. Today's compilers are smart, I've heard.

exoteric
I : Next<I>

In reply to Dodo

#Oct 18th @ 4:44 AM

It's just for fun, I don't think contextfree would use that stuff IRL Wink

contextfree

In reply to exoteric

#Oct 18th @ 4:57 AM

My current project at work has frazzled me so much that I don't know what is or isn't real life anymore ... am I a butterfly dreaming I'm a man, or ... Perplexed

figuerres
???

Teach a man to fish and he will feed himself.

teach a programmer to use a rope and he will hang himself.

keep the rope locked up around programmers!

exoteric
I : Next<I>

In reply to figuerres

#Oct 18th @ 5:12 AM

Teach a man Brainf* and he'll go f* himself Big Smile

- Actually, Erik mentioned that all that's needed is the K-combinator (as in the SKI combinator calculus). If that's the case, then Brainf* is massive overkill. So K is like the assembly language of functional programming.

blowdart
Peek-a-boo

In reply to exoteric

#Oct 18th @ 6:57 AM

Lambdas are rapidly turning into the regular expressions of .NET ...

staceyw
Before C# there was darkness...

In reply to contextfree

#Oct 18th @ 5:10 AM

Another reason I don't like single line gumbo is debug stepping. It is much easier when things are on seperate lines - besides being easier to reason about in general. A downside of multi-line lambdas also, you break on the whole thing, not inside.

stevo_
Human after all

Ugh..

Minh
WOOH! WOOH!

In reply to Sven Groot

#Oct 17th @ 10:53 PM

Dang he actually convinced me there is no , operator... I knew I've seen it