As Fabian says, if it's likely that your IList is just pointing to a
List<T>, then casting would be most performant.
Otherwise, List<T> is just a wrapper for an array. List<T>(IEnumerable<T>
enumerable) simply checks is enumerable is a collection and if it is
simply calls ICollection<T>.CopyTo to copy the collection to a new array.
Depending on how your using List<T> (i.e. not modifying it), you might
find that using an array to be a bit quicker.
On Thu, 5 Apr 2007 13:35:03 +0200, Fabian Schmied <[EMAIL PROTECTED]>
wrote:
>> Is there a better way to cast an IList to List other than how I am
doing it here:
>>
>> get
>> {
>> IList<IRecipeStep> result = (_recipeMode == Mode.Temp) ?
_recipeUsersDictionary[AdminUserUid].RecipeSteps : _liveRecipe.RecipeSteps;
>> PersistentGenericBag<IRecipeStep> bag =
(PersistentGenericBag<IRecipeStep>)result;
>> return new List<IRecipeStep>((IEnumerable<IRecipeStep>)bag);
>> }
>
>If you suspect that the IList<T> might be an implementation of List<T>
>(rather than an array or something), you can just try to cast it;
>otherwise, you'll have to construct a new List<T> and copy the source,
>as you do it
>
> I.e.:
>
>public static List<T> MakeList<T>(IList<T> sourceList)
>{
> List<T> resultList = sourceList as List<T>;
> if (resultList == null)
> {
> resultList = new List<T> (sourceList);
> }
> return resultList;
>}
>
>However, constructing a new list like that might be a lengthy
>operation, depending on how long the source list is. It's therefore
>questionable if one should do it in a property getter - property
>getters should be quite fast, more like a field access than like a
>longer calculation.
>
>> I prefer to work with an List instead of an IList so I can use the
functional list processing with annonymous delegates.
>
>Yes, it's a real shame that these algorithms are only implemented on
>List<T> and on Array in the .NET framework. You can use the free
>Wintellect PowerCollections, though, which implement them (and many
>more) for the most general IEnumerable<T>. Then you wouldn't need to
>cast/copy any longer.
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