Are the following data type allocations analagous?

Question

I'm very interested in languages and their underpinnings, and I'd like to pose this question to the community. Are the following analagous to eachother in these languages?

C#

Foo bar = default(Foo); //alloc
bar = new Foo(); //init

VB.NET

Dim bar As Foo = Nothing  'alloc
bar = New Foo()   'init

Objective-C

Foo* bar = [Foo alloc];   //alloc
bar = [bar init];    //init

Answer 1

The type Foo can either be a Value Type or a Reference Type, except in Objective-C of course.

Assuming Foo is a reference type, then for C# and VB.NET the first line will not allocate any memory for the object were as the Objective-C first line will actually allocate the memory, so this is a difference. The .NET languages perform the allocation and initialization in one line in the second line.

In the case that Foo is a Value Type, then the .NET languages are analagous to each other, Objective-C does not have value types (at least not the last time I worked with it 15 years ago).

Answer 2

You're overwriting bar in both C# and VB.NET. Your code is equivalent to just:

Foo bar;  // does nothing but declare a handle
bar = new Foo(); // alloc AND init

or simply:

Foo bar=new Foo();

Where Obj-C apparently separates allocation from initialization, all other C++-like languages combine the 2, thinking (correctly imo) that you never want to have partially-uninitialized objects (constructors aside, of course).