Re: Most efficient way to iterate through an NSArray
Re: Most efficient way to iterate through an NSArray
- Subject: Re: Most efficient way to iterate through an NSArray
- From: David Avendasora <email@hidden>
- Date: Mon, 17 Mar 2008 15:12:20 -0400
It's good to know this. I have just found myself using it a lot and
wanted to know if I was doing things the right way or not. If you
hadn't noticed, in the past, several of my practices were considered
less than optimal. :-)
I guess I now have reading to do on Batch Fetching...
Dave
On Mar 17, 2008, at 2:53 PM, Mike Schrag wrote:
Yeah ... +1 here. By far your performance problems are going to be
inefficient use of EOF. For instance, if you're traversing
relationships of relationships, you will want to make sure you have
batch fetched them appropriately. See ERXRecursiveBatchFetching in
Wonder.
ms
On Mar 17, 2008, at 2:47 PM, Chuck Hill wrote:
Enumeration should be slightly slower.
But you are wasting your time looking at this to optimize your WO
apps. Go find a real problem.
Chuck
On Mar 17, 2008, at 11:34 AM, Timmy wrote:
All:
How does java Enumeration compare to this with regard to
performance? I iterate through my EO's almost always using
Enumeration - um because that's how I was "learned."
T
-----
Programmer/Analyst
Graduate School of Education and Information Studies
University of California Los Angeles
On Mar 17, 2008, at 9:52 AM, Chuck Hill wrote:
On Mar 17, 2008, at 3:41 AM, David Avendasora wrote:
Hi all,
I find myself often times needing to iterate through an NSArray
of EOs. I'm not sure if the way I'm doing it is the most
effecient or not. Here's what I normally do:
public void doThisForAllProducts(EOEditingContext ec) {
for (Object aProductObject : products().toArray()) {
Product aProduct = (Product) aProductObject;
aProduct.doThis(ec);
}
}
First off, passing an ec to an eo seems pointless / dangerous,
unless you are returning a local instance of it. Which you aren't.
Second, define "efficient". If you mean in terms of execution
speed, that is probably the fastest. An old fashioned for loop
using objectAtIndex() might be a few milliseconds faster. If you
mean efficient as in "least amount of code", rely on KVC:
products().valueForKey("doThis");
Using KVC will be a bit slower than a raw for loop.
This is assuming that products() is an NSArray of Product EOs.
Is this a good / the best way to iterate through NSArrays in
general?
I find myself occasionally nesting this loop a couple deep to
drill down into several toMany relationships. For example (as a
keypath): products.billsOfMaterial.routingSteps.components to
get all the components that are possibly used in a product.
Using KVC on that is not likely to yield the results that you
expect.
On a side note, and the reason for calling products().toArray()
is to force EOF to get the real EOs and not just faults. If I
just call products() I'll sometimes get EOs, sometimes faults,
seemingly by EOF whim. Is that a bug or expected behaviour?
I don't (don't ask) use the new for style. But there was a bug
in NSArray where iterator() (or some similar method) did not fire
the faults. I thought this had been fixed, but maybe not until
5.4. Of course, if you are using Wonder's "not broken" NSArray...
Chuck
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--
Practical WebObjects - for developers who want to increase their
overall knowledge of WebObjects or who are trying to solve specific
problems.
http://www.global-village.net/products/practical_webobjects
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