Beginners Question on 'return'

[Martijn Mulder]

I just want to be sure about this. When I have code like this:

//data member
System.Drawing.Drawing2D.GraphicsPath graphicspath=new
System.Drawing.Drawing2D.GraphicsPath();

//method
public System.Drawing.Drawing2D.GraphicsPath GetGraphicsPath()
{
return graphicspath;
}

there is a reference, a pointer returned to 'graphicspath' and NOT a copy of
the object?

 

[Jon Skeet [C# MVP]]

I just want to be sure about this. When I have code like this:

//data member
System.Drawing.Drawing2D.GraphicsPath graphicspath=new
System.Drawing.Drawing2D.GraphicsPath();

//method
public System.Drawing.Drawing2D.GraphicsPath GetGraphicsPath()
{
return graphicspath;
}

there is a reference, a pointer returned to 'graphicspath' and NOT a copy of
the object?

If GraphicsPath is a class, then the value returned is a reference.
If GraphicsPath is a struct, then the value returned is a shallow copy
of the data.

(I don't have the docs to hand to check which is the case, but it's
worth knowing the general principles.)

Jon

 

[HuffmaN]

Hi, wot 's meaning of "shallow copy"?

If GraphicsPath is a class, then the value returned is a reference.
If GraphicsPath is a struct, then the value returned is a shallow copy
of the data.

(I don't have the docs to hand to check which is the case, but it's
worth knowing the general principles.)

Jon

 

[Christof Nordiek]

Hi, wot 's meaning of "shallow copy"?

In this context it means:
A copy of the instance fields if the struct
fields of a valuetype are copied in the same way.
fields of a referencetype are set to the same instance.

 

[Jon Skeet [C# MVP]]

Hi, wot 's meaning of "shallow copy"?

Well, how did your Google search turn out? A Google search for:
"shallow copy" .NET
gives me lots of results which look promising.

It's always worth trying a simple search before asking a question.

Jon

 

[clintonG]

Doesn't the method signature itself answer the question or indicate the
implied return type?

<%= Clinton Gallagher
NET csgallagher AT metromilwaukee.com
URL http://clintongallagher.metromilwaukee.com/
MAP 43°2'17"N 88°2'37"W : 43°2'17"N 88°2'37"W

 

[Jon Skeet [C# MVP]]

Doesn't the method signature itself answer the question or indicate the
implied return type?

Well, it answers in terms of what the type is. It doesn't answer the
question as to how return values are handled, or fill in my ignorance
as to whether GraphicsPath is a struct or a class.

 

[Martijn Mulder]

fill in my ignorance as to whether GraphicsPath is a struct or a class.


GraphicsPath is a class