is there a foreach performance issue when using complex expressions?

[Benjamin Joldersma]

Hi all,

If I have a expensive public property that exposes a collection, say
via a call to a database:

public ArrayList Complex
{
get
{
//expensive call to db
return DbResult;
}
}

and use this in a foreach:

foreach( object o in Complex )
{
...
}

Will the clr call Complex only once, and save a reference to the
direct variable actually exposed, or will it execute the code in the
get routine each iteration?

Thanks in advance,

Ben Joldersma
Sr. Software Engineer,
Citadel Media, Inc.

[Jon Skeet]

Benjamin Joldersma <be**@theinsiders.com> wrote:

<snip>

Will the clr call Complex only once, and save a reference to the
direct variable actually exposed, or will it execute the code in the
get routine each iteration?

It calls it once, and gets an iterator. So no, you don't need to worry
about the time it takes to evaluate that.

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

[Ignacio Machin \( .NET/ C# MVP \)]

Hi Benjamin,

It call it once.

This is VERY easy to check ( I just did it ), just put a breakpoint inside
the get method , you will see it only enters once.

Cheers,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation

"Benjamin Joldersma" <be**@theinsiders.com> wrote in message
news:8f**************************@posting.google.c om...

Hi all,

If I have a expensive public property that exposes a collection, say
via a call to a database:

public ArrayList Complex
{
get
{
//expensive call to db
return DbResult;
}
}

and use this in a foreach:

foreach( object o in Complex )
{
...
}

Will the clr call Complex only once, and save a reference to the
direct variable actually exposed, or will it execute the code in the
get routine each iteration?

Thanks in advance,

Ben Joldersma
Sr. Software Engineer,
Citadel Media, Inc.

[Benjamin Joldersma]

Thanks so much for checking. I should have thought of that!

-----Original Message-----
Hi Benjamin,

It call it once.

This is VERY easy to check ( I just did it ), just put a breakpoint insidethe get method , you will see it only enters once.

Cheers,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation

"Benjamin Joldersma" <be**@theinsiders.com> wrote in message
news:8f**************************@posting.google. com...

Hi all,

If I have a expensive public property that exposes a collection, say via a call to a database:

public ArrayList Complex
{
get
{
//expensive call to db
return DbResult;
}
}

and use this in a foreach:

foreach( object o in Complex )
{
...
}

Will the clr call Complex only once, and save a reference to the direct variable actually exposed, or will it execute the code in the get routine each iteration?

Thanks in advance,

Ben Joldersma
Sr. Software Engineer,
Citadel Media, Inc.

.

[Benjamin Joldersma]

-----Original Message-----
Benjamin Joldersma <be**@theinsiders.com> wrote:

<snip>

Will the clr call Complex only once, and save a reference to the direct variable actually exposed, or will it execute the code in the get routine each iteration?
It calls it once, and gets an iterator. So no, you don't

need to worryabout the time it takes to evaluate that.

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