Jess Liberty's C# book on C#

[Emmanuel Godet]

Hi,
can someone explain the following extract from Jess Liberty's C# book
(very end of chapter on structs)?
"Be careful about using properties. Although these allow you to
support encapsulation by making the actual values private, the
properties themselves are actually member methods and you cannot call
a member method until you initialize all the member variables". I
don't understand what he means.
Cheers,
Emmanuel

 

[Nick Chakarov]

I guess that means ... that anybody can write and publish book
Cheers,
Nick

 

[Steve Walker]

Hi,
can someone explain the following extract from Jess Liberty's C# book
(very end of chapter on structs)?
"Be careful about using properties. Although these allow you to
support encapsulation by making the actual values private, the
properties themselves are actually member methods and you cannot call
a member method until you initialize all the member variables". I
don't understand what he means.

Nor do I. The compiler barfs on a struct without a constructor, a struct
constructor which doesn't initialise all fields, and any attempt to
access an uninitialised struct. So how can you get your hands on a
struct which has uninitialised member variables?

 

[Henrik Dahl]

Hello!

Have you already read and understood "Inside C#" from MS Press, otherwise,
you could consider that as an alternative.


Best regards,

Henrik Dahl

 

[Microsoft]

If you know what that paragraph means, it'd be easier and far more helpful
to help describe what it's saying instead of pointing out yet more books to
read. Not everyone can afford to buy and read each and every book about a
particular subject.

 

[James Curran]

I believe he is saying the you cannot use properties to assign a
member's initial value:

MyClass m = new MyClass(); // initialization must be done here.
m.A = 1; // you can only change a value, not initially assign
it here.
m.B = 2;
--
--
Truth,
James Curran
[erstwhile VC++ MVP]

Home: www.noveltheory.com Work: www.njtheater.com
Blog: www.honestillusion.com Day Job: www.partsearch.com

 

[Richard Blewett [DevelopMentor]]

Consider this struct

struct Point
{
int x;
public int X
{
get{ return x; }
set{ x = value; }
}
int y;
public int Y
{
get{ return y; }
set{ y = value; }
}
}

now lets use it in some code

Point p = new Point();
p.X = 10;
p.Y = 20;

this works as the ctor initializes the stucts memory to 0.

However if we change the code to:

Point p;
p.X = 10;
p.Y = 20;

This won't compile as the memory has not been initialized and the property sets are actually method calls.

The only way to make code like that work is to have the fields as public then you can write

Point p = new Point();
p.x = 10;
p.y = 20;

which is allowed. Until you have initialized every field of the struct you cannot call a method on it. You can do this initialization manually or via a constructor. Jesse is saying that you cannot perform this initialization via property sets as they are in fact method calls

Regards

Richard Blewett - DevelopMentor
http://www.dotnetconsult.co.uk/weblog
http://www.dotnetconsult.co.uk

Hi,
can someone explain the following extract from Jess Liberty's C# book
(very end of chapter on structs)?
"Be careful about using properties. Although these allow you to
support encapsulation by making the actual values private, the
properties themselves are actually member methods and you cannot call
a member method until you initialize all the member variables". I
don't understand what he means.
Cheers,
Emmanuel