[AccessD] DotNet passing by value

John,

AFAIK VBA passes ByVal strings by reference but it first makes the copy of
the string to the heap memory...
The same should be true for  VB.NET/C#.
So, one million bytes' length string will be copied to the heap memory and
then passed internally by ref. Heap memory is handled by virtual memory
management system - it should work rather well if one has speedy moderrn
HHDs for automatic swapping...

But of course passing one million bytes long strings as a ByVal parameter
isn't a good idea at all....

> As you know, everything in .net is an object
Yes, everything is an object but scalar types are used internall as they
are usually used in unmanaged systems - this optimization is done by .NET
Framework compilers. When a scalar type has to be treated as an object it is
getting "boxed" - boxing is a  ,NET Framework term:

See also:

Writing Faster Managed Code: Know What Things Cost
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dndotnet/html/fastmanagedcode.asp

Shamil

----- Original Message ----- 
From: "John W. Colby" <jwcolby at colbyconsulting.com>
To: "'Access Developers discussion and problem solving'"
<accessd at databaseadvisors.com>
Sent: Friday, August 26, 2005 3:21 PM
Subject: RE: [AccessD] DotNet passing by value


> Oooops...
>
> >.. passing anything else (including strings) by value.
>
> Should have said "by reference", i.e. placing a pointer to the object on
the
> stack.
>
> John W. Colby
> www.ColbyConsulting.com
>
> Contribute your unused CPU cycles to a good cause:
> http://folding.stanford.edu/
>
> -----Original Message-----
> From: accessd-bounces at databaseadvisors.com
> [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of John W. Colby
> Sent: Friday, August 26, 2005 7:11 AM
> To: dba-vb at databaseadvisors.com; 'Access Developers discussion and
> problemsolving'
> Subject: [AccessD] DotNet passing by value
>
>
> As you might be aware, VB.Net (and I assume the other .net languages as
> well) pass all variables by value.  But what does this mean, and is it
true.
> As you know, everything in .net is an object, even common variables such
as
> an integer or decimal etc.  Passing by value (in other languages) means
> placing a COPY of the variable (or object in this case) on the stack as
the
> function is called.  In VBA for example, when you pass by value, it really
> does ONLY for the simple data types, passing anything else (including
> strings) by value.
>
> Imagine passing a string, which could be a million bytes, by value -
> literally making a copy and passing that into the stack.  IIRC the total
> stack space for a given program in an Intel machine is something like 128
> kbytes which means that passing a single (huge) string by value could
cause
> a stack overflow.  Now DotNet comes along claiming to pass everything by
> value.  Is this more doublespeak?  And if so, what is the truth?
>
> John W. Colby
> www.ColbyConsulting.com
>
> Contribute your unused CPU cycles to a good cause:
> http://folding.stanford.edu/
>
>
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