foreach keyword or ForEach<T> extension method?

re: foreach keyword or ForEach extension method?

Richard Collette — Mon, 27 Apr 2009 19:22:43 GMT

From a performance standpoint it matters. Lambdas are essentially delegates and do not perform as well as a normal loop structure. Test it.

At best you're only saving a few keystrokes, maybe none depending on what intellisense does for you between the two versions.

This is trying to solve a problem that doesn't exist. I will admit that I sometimes take the slight performance hit and Linq/Lambdas when it makes the code more readable. But in critical loops and where the Linq code may actually read more complex, I will use a normal loop construct.

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re: foreach keyword or ForEach extension method?

simonince — Mon, 27 Apr 2009 22:21:21 GMT

@ Richard,

Good points - and a balanced approach I think.

For most code I write, though, the overhead of using delegates/lambdas is worthwhile for code readability... unless they're used so much that readability actually gets worse, which I guess is the point of the post!

Simon

re: foreach keyword or ForEach extension method?

MichaelGG — Tue, 28 Apr 2009 07:48:55 GMT

I'm lucky I guess that most of my perf can be found with better algorithms. I can only recall a few times where the overhead of delegate invocation was an issue, and once of those was a bug in the CLR.

foreach has overhead too, versus a for loop and manual indexing. Maybe the compiler optimizes it on some types, but I don't believe it does on any IList.

In F#, I write much less efficient code, and it's very rarely a problem. If I do profile and find a certain path is slow, fine, move back to mutables and even pointers if necesary. But I highly doubt that many people work in application where these sort of optimizations are needed all the time...

re: foreach keyword or ForEach extension method?

simonince — Tue, 28 Apr 2009 11:30:33 GMT

@ Michael;

Ditto - every now and then some code needs low level tuning, but I prioritise maintainability first by default... generally it is architectural decisions that impact perf more in the fields I do most work in.

But what's interesting is that you use F# - so you're used to the functional paradigm... as am I from quite some time ago, but others may not be. I wonder if this makes you (and I) more accepting of lambdas etc as programming constructs as it is just a natural fit?

Simon

re: foreach keyword or ForEach extension method?

MichaelGG — Tue, 28 Apr 2009 14:24:03 GMT

F# introduced me to the functional mindset, but before I could use F#, I had a couple of years of full time C# (and still have a lot of C# still).

The fact C# came out with a nice intro FP feature set with 3.0 was a sanity-saving bonus :).

Personal experience tells me as soon as a C# programmer "gets it" -- they grasp they can toss around functions -- they tend to love it and use it tons. Anyone who likes LINQ is pretty much validating that, don't you think?