Strange behaviour on ByVal parameter ???

[serge calderara]

Dear all,

I have really strange behviour when passing an object to a
function by value:

if I create a new object of myClass from the main
application as follow:

myObj = new (ObjSource)

then the instance is creted on a separate assambly an
reach the code of the constructor of myClass
public sub new (byval obj as object)

.....
....

' here I try to channge some object value
obj.name ="test"
end sub

At this time when the object is created and I return to
the calling point in my main application , the object is
also modifed in the main application, and it should be not
as it is pass by value to the constructo of myClass !!

What did I miss here?

thnaks for your information
regards
Serge

[Uri Dor]

you're passing an object, so its "pointer" is passed by value. the
object itself isn't copied, so the changes you make to the object remain.

there's a reason "reference types" are so called - they're always passed
by reference.

serge calderara wrote:

Dear all,

I have really strange behviour when passing an object to a
function by value:

if I create a new object of myClass from the main
application as follow:

myObj = new (ObjSource)

then the instance is creted on a separate assambly an
reach the code of the constructor of myClass
public sub new (byval obj as object)

.....
....

' here I try to channge some object value
obj.name ="test"
end sub

At this time when the object is created and I return to
the calling point in my main application , the object is
also modifed in the main application, and it should be not
as it is pass by value to the constructo of myClass !!

What did I miss here?

thnaks for your information
regards
Serge

[serge calderara]

Thnaks so much for your answer
I was starting to loose my hairs

Serge

-----Original Message-----
you're passing an object, so its "pointer" is passed by value. theobject itself isn't copied, so the changes you make to the object remain.
there's a reason "reference types" are so called - they're always passedby reference.

serge calderara wrote:

Dear all,

I have really strange behviour when passing an object to a function by value:

if I create a new object of myClass from the main
application as follow:

myObj = new (ObjSource)

then the instance is creted on a separate assambly an
reach the code of the constructor of myClass
public sub new (byval obj as object)

.....
....

' here I try to channge some object value
obj.name ="test"
end sub

At this time when the object is created and I return to
the calling point in my main application , the object is also modifed in the main application, and it should be not as it is pass by value to the constructo of myClass !!

What did I miss here?

thnaks for your information
regards
Serge

.

[Jon Skeet [C# MVP]]

serge calderara <an*******@discussions.microsoft.com> wrote:

Thnaks so much for your answer
I was starting to loose my hairs

For more information about this (using C# terminology, but the
principles are the same) see
http://www.pobox.com/~skeet/csharp/parameters.html

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too