C# will allow to create an object using either Object() or Object{}. What is the difference with Object() and Object{}
public item getitem()
{
return new item()
}
public item getitem()
{
return new item {}
}
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See: What's the difference between an object initializer and a constructor?YetAnotherUser– YetAnotherUser2012-07-20 16:07:42 +00:00Commented Jul 20, 2012 at 16:07
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I got it already but now I know from Jon skeet that Object{} calling parameter less constructor implicitly.amesh– amesh2012-07-20 16:14:42 +00:00Commented Jul 20, 2012 at 16:14
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3 Answers
This syntax:
new SomeType{}
is an object initializer expression which happens to set no properties. It calls the parameterless constructor implicitly. You can add property assignments within the braces:
new SomeType { Name = "Jon" }
This syntax:
new SomeType()
is just a call to the parameterless constructor, with no opportunities to set properties.
Note that you can explicitly call a constructor (paramterized or not) with an object initializer too:
// Explicit parameterless constructor call
new SomeType() { Name = "Jon" }
// Call to constructor with parameters
new SomeType("Jon") { Age = 36 }
See section 7.6.10.2 of the C# 4 specification for more details about object initializers.
I would highly recommend that if you aren't setting any properties, you just use new SomeType() for clarity. It's odd to use an object initializer without setting any properties.
2 Comments
Peter
Could you please explain your last point? What would the constructors look like for these two examples?
Jon Skeet
@Peter: There'd be one constructor without parameters and one constructor with a string parameter. They'd be perfectly normal constructors. The type itself doesn't need to know anything about whether object initializers are being used.
item() calls default constructor, whereas item {} calls default constructor and allows to use (empty in this case) object initializer.
Comments
new item {} uses an object initializer. In your example, there is no difference, but normally you would just call new item() if you don't wish to actually utilize the object initializer.
