collections

PropertyGrid - Ilist Collection Remove not firing as expected

I have a collection object that implements IList. Inside the collection I have used a List to collect the items. Inside the PropertyGrid (at runtime), it binds properly and the Collection Editor opens. I can edit, and I can add items properly and I can catch these methods when they are used in the collection class. However, if you try t...

ReadOnlyCollection or IEnumerable for exposing member collections?

Is there any reason to expose an internal collection as a ReadOnlyCollection rather than an IEnumerable if the calling code only iterates over the collection? class Bar { private ICollection<Foo> foos; // Which one is to be preferred? public IEnumerable<Foo> Foos { ... } public ReadOnlyCollection<Foo> Foos { ... } } /...

Why does WCF return myObject[] instead of List<T> like I was expecting?

I am returning a List from my WCF method. In my client code, it's return type shows as MyObject[]. I have to either use MyObject[], or IList, or IEnumerable... WCFClient myClient = new WCFClient(); MyObject[] list = myClient.GetMyStuff(); or IList<MyObject> list = myClient.GetMyStuff(); or IEnumerable<MyObject> list = my...

Can I use a collection initializer for Dictionary<TKey, TValue> entries?

I want to use a collection initializer for the next bit of code: public Dictionary<int, string> GetNames() { Dictionary<int, string> names = new Dictionary<int, string>(); names.Add(1, "Adam"); names.Add(2, "Bart"); names.Add(3, "Charlie"); return names; } So typically it should be something like: return new Dicti...

What advantage do you get with a collection over List(Of T) in .NET 2.0+

I had another developer ask why I use List all over the place ... and I thought about it for a minute ... and couldn't come up with a definitive answer. If you inherit from the collection base class to extend instead of using List(Of T) - what advantages do you get? Or - what don't you get with List? ...

Iterating over Java Collections in Scala

I'm writing some Scala code which uses the Apache POI API. I would like to Iterate over the Rows contained in the java.util.Iterator that I get from the Sheet class. I would like to use the Iterator in a for each style loop, so I have been trying to convert it to a native Scala collection but will no luck. I have looked at the Scala Wra...

Best way to pass Entity Framework entity collections from the DAL to the Business Layer?

I have a DAL that makes calls to my Entity Framework Model. The calls return things like IOrderedQueryable and IQueryable objects. Should I convert them to something more universal in my DAL, such as List? But I assume that if I don't need to enumerate through the entire collection, this could be wasteful... So whats the best approac...

Best way to convert an IEnumerable<T> to an T[]

What is the best way to convert from a generic IEnumerable object to an array of the same type? The current solution I have looks like the following: IEnumerable<string> foo = getFoo(); string[] bar = new List<string>(foo).ToArray(); The transfer through a List<T> seems unneccesary, but I haven't been able to find a better way to do ...

Building resultset using collection object

Hi, I had an issue in building the resultset using java. Here it goes... I am storing a collection object which is organized as row wise taken from a resultset object and putting the collection object(which is stored as vector/array list) in cache and trying to retrieve the same collection object. Here i need to build back the resultse...

Collections from LINQ to SQL and the ability to filter

Hi, I have asked this question on more than one forums and it seems no one would even want to take a crak at it. My problem is simple and i would guess everyone has run into it when using LINQ to SQL. If your have a LINQ object called: Person and you would like to poulate a list box based on all of the people you have in your DB the ta...

how to add opaque types to collections

How can I add an opaque type to a collection in cocoa? I get a compiler warning for this (obviously, because opaque types are not objects): CGColorSpaceRef colorSpace; NSArray *myArray = [NSArray arrayWithObject:colorSpace]; ...

How to count occurrence of an element in a List

I have an ArrayList a collection class of java as follows. ArrayList<String>animals = new ArrayList<String>(); animals.add("bat"); animals.add("owl"); animals.add("bat"); animals.add("bat"); As you can see the animals ArrayList consists of 3 bat elements and one owl element. I was wondering if there is any API in collection framework ...

How can I remove items from a Collection with filter function, and then add new items that don't meet the filter criteria?

I have a Collection, and I want to remove all items that have a certain property set to true. I use a filterFunction to accomplish this. My question is, how can I add new items to the Collection that have that property set to true? The filterFunction is still applied, and the item is not added.... Do I have to iterate through the entire...

Is there a way to get a collection of all the Models in your Rails app?

Is there a way that you can get a collection of all of the Models in your Rails app? Basically, can I do the likes of: - Models.each do |model| puts model.class.name end Thanks in advance. ...

Linq to SQL and Collection operations

I have a Dictionary which I'd like to use like an IN clause within a SQL query. I have a Linq-To-SQL query where I would like to use this Dictionary's Keys to check fields in the rows for the query. E.g. bool result = DataContext.Table.Any(res => MyDictionary.ContainsKey(res.field1)); In effect this is similar to exists(sel...

Cannot implicitly convert List<T> to Collection<T>

This is a compiler error (slightly changed for readability). This one always puzzled me. FxCop tells that this is a bad thing to return List and classes that are\derived from Collection<T> should be preferrable as return types. Also, FxCop says that it is OK to use List<T> for internal data storage\manipulation. Ok, I get it, but what ...

Recieving Disparate Content In Java

The Problem: I need to receive different types of content from a number of different sources normalize them and then make them persistent through JDO. Naive Solution?: Create and listen on a specific port for each data type. OR Do a bunch of complicated parsing A Seemingly Ideal Solution: Have custom URL types Ie. FOO://myhost.tl...

Creating a blocking Queue<T> in .NET?

I have a scenario where I have multiple threads adding to a queue and multiple threads reading from the same queue. If the queue reaches a specific size all threads that are filling the queue will be blocked on add until an item is removed from the queue. The solution below is what I am using right now and my question is: How can this b...

Huge collections in Python

Basically I am storing millions of vector3 values in a list. But right now the vector3s are defined like so: [5,6,7] which I believe is a list. The values will not be modified nor I need any vector3 functionality. Is this the most performant way to do this? ...

How to add a inner mapping in a nested collection?

Given: Object nestKey; Object nestedKey; Object nestedValue; Map<T,Map<T,T>> nest; Map<T,T> nested; How is a mapping added to nested where: nest.containsKey(nestKey) == true; ? Or is there an existing library of collections that would be more effective? ...