constant references

[Zytan]

Are they possible? I am passing in a large array of Bytes, thus I
don't want to use ByVal.

Zytan

[Branco Medeiros]

Zytan wrote:

Are they possible? I am passing in a large array of Bytes, thus I
don't want to use ByVal.

When you pass an array by value, there's no copy of the array
contents, just of the array *variable*.

HTH.

Regards,

Branco,

[Zytan]

Branco,

I had actually typed up a lengthy post asking about that, as well, and
Google Groups did something strange, and loaded a new page, erasing
the whole thing (one major flaw of web apps -- load a new page by
accident, and say goodbye to all your work), so I forgot about it, and
just asked the basic question.

I was going to ask if array variables are like C++ arrays (i.e. like
pointers), so that even if the 'pointer' is const, you can still
change what it points to (unless that is also const). All VB .NET
help files and tutorials never even touch upon these things. Very
annoying. It's like they think the programmer shouldn't be thinking
about these things...

Anyway... that leads to the question:

How can I pass in an array to a function/sub so that the entire array
is const and cannot be changed? Or should I be using C# instead for
such functionality?

Thanks for your reply,

Zytan

[Herfried K. Wagner [MVP]]

"Zytan" <zy**********@y ahoo.comschrieb :

How can I pass in an array to a function/sub so that the entire array
is const and cannot be changed? Or should I be using C# instead for
such functionality?

This cannot be done, not in VB and not in C#. You'd have to pass a copy of
the array or a proxy object to the function.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>

[Stephany Young]

This is one of those:

Patient: "Doctor! It hurts when I do this."
Doctor: "Well don't do that!"

questions.

If you don't want the passed in array changed in your function, then don't
change it in your function!
"Zytan" <zy**********@y ahoo.comwrote in message
news:11******** **************@ v33g2000cwv.goo glegroups.com.. .

Branco,

I had actually typed up a lengthy post asking about that, as well, and
Google Groups did something strange, and loaded a new page, erasing
the whole thing (one major flaw of web apps -- load a new page by
accident, and say goodbye to all your work), so I forgot about it, and
just asked the basic question.

I was going to ask if array variables are like C++ arrays (i.e. like
pointers), so that even if the 'pointer' is const, you can still
change what it points to (unless that is also const). All VB .NET
help files and tutorials never even touch upon these things. Very
annoying. It's like they think the programmer shouldn't be thinking
about these things...

Anyway... that leads to the question:

How can I pass in an array to a function/sub so that the entire array
is const and cannot be changed? Or should I be using C# instead for
such functionality?

Thanks for your reply,

Zytan

[Zytan]

Herfried,

This cannot be done, not in VB and not in C#. You'd have to pass a copy of
the array or a proxy object to the function.

I cannot *believe* this cannot be done. Wow... Ouch!

I know I can pass a copy (made with care) of the array, so that any
changes made within the function will not affect the original. But,
creating a copy of an array is a horrible thing to do when it needn't
be done... What terrible programming that would be, indeed. In my
case, I have an array of several MB in size.

Please elaborate on "proxy object".

Thanks for your reply,

Zytan

[Zytan]

Stephany,

This is one of those:

Patient: "Doctor! It hurts when I do this."
Doctor: "Well don't do that!"

questions.

If you don't want the passed in array changed in your function, then don't
change it in your function!

No, no, no! This is very, very bad way of thinking about it. My
program doesn't change the array inside of the function. Really. I'm
a good programmer. Trust me. But, the point is... I don't trust
myself. The reason "const" exists is to prevent me from making
mistakes. Even the smartest of us make mistakes. The compiler helps
us avoid pitfalls with concepts like "const" and encapsulation. They
force good programming. That's why good programmers use them. I
can't even begin to explain how astonished I am at your reply...

I am further astonished that VB offers no way to protect programmers
from being stupid with passing in arrays. And that even C# doesn't
have this. I am just amazed... the fact that all VB programmers out
there in VB land are programming without this protection... and now
your reply makes more sense to me. Because it's the only solution, it
is the only way you CAN think about it. Amazing. (that is... unless
the proxy objects that Herfried mentioned are a solution...?)

Zytan

[Herfried K. Wagner [MVP]]

"Zytan" <zy**********@y ahoo.comschrieb :

>This cannot be done, not in VB and not in C#. You'd have to pass a copy
of
the array or a proxy object to the function.

Please elaborate on "proxy object".

\\\
Public Class ArrayProxy(Of T)
Private m_Array() As T

Public Sub New(ByVal Array() As T)
m_Array = Array
End Sub

Default Public ReadOnly Property Items(ByVal Index As Integer) As T
Get
Return m_Array(Index)
End Get
End Property
End Class
....
Dim Names() As String = ...
Foo(..., New ArrayProxy(Of String())(Names )), ...)
///

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>

[Stephany Young]

Yes you're absolutely right - the best of us do make mistakes.

That is why we have robust debugging and testing techniques.

Checking that some variable that shouldn't be modified hasn't been is the
most the most basic of those techniques.
"Zytan" <zy**********@y ahoo.comwrote in message
news:11******** *************@v 45g2000cwv.goog legroups.com...

Stephany,

>This is one of those:

Patient: "Doctor! It hurts when I do this."
Doctor: "Well don't do that!"

questions.

If you don't want the passed in array changed in your function, then
don't
change it in your function!

No, no, no! This is very, very bad way of thinking about it. My
program doesn't change the array inside of the function. Really. I'm
a good programmer. Trust me. But, the point is... I don't trust
myself. The reason "const" exists is to prevent me from making
mistakes. Even the smartest of us make mistakes. The compiler helps
us avoid pitfalls with concepts like "const" and encapsulation. They
force good programming. That's why good programmers use them. I
can't even begin to explain how astonished I am at your reply...

I am further astonished that VB offers no way to protect programmers
from being stupid with passing in arrays. And that even C# doesn't
have this. I am just amazed... the fact that all VB programmers out
there in VB land are programming without this protection... and now
your reply makes more sense to me. Because it's the only solution, it
is the only way you CAN think about it. Amazing. (that is... unless
the proxy objects that Herfried mentioned are a solution...?)

Zytan

[Cor Ligthert [MVP]]

Zytan,

This discussion is already from the first beta versions. In my idea are you
right, but this seems to be a hobby from the main architect from the Net
languages. (And unchangable now of course)

Cor

"Zytan" <zy**********@y ahoo.comschreef in bericht
news:11******** *************@v 45g2000cwv.goog legroups.com...

Stephany,

>This is one of those:

Patient: "Doctor! It hurts when I do this."
Doctor: "Well don't do that!"

questions.

If you don't want the passed in array changed in your function, then
don't
change it in your function!

No, no, no! This is very, very bad way of thinking about it. My
program doesn't change the array inside of the function. Really. I'm
a good programmer. Trust me. But, the point is... I don't trust
myself. The reason "const" exists is to prevent me from making
mistakes. Even the smartest of us make mistakes. The compiler helps
us avoid pitfalls with concepts like "const" and encapsulation. They
force good programming. That's why good programmers use them. I
can't even begin to explain how astonished I am at your reply...

I am further astonished that VB offers no way to protect programmers
from being stupid with passing in arrays. And that even C# doesn't
have this. I am just amazed... the fact that all VB programmers out
there in VB land are programming without this protection... and now
your reply makes more sense to me. Because it's the only solution, it
is the only way you CAN think about it. Amazing. (that is... unless
the proxy objects that Herfried mentioned are a solution...?)

Zytan