"sales engineer" - isn't that an oxymoron? :)
---
Billy Cravens
HR Web Systems, EDS
[EMAIL PROTECTED]
----- Original Message -----
From: "Hinojosa, Robert A" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, July 31, 2001 11:03 AM
Subject: RE: question.
> I was told by an allaire sales engineer once that *supposedly* all vars
are
> stored inside different hashtables in the CF Engine. So my guess would be
> that in C++ you could use enumeration to see if that var existed in the
> hashtable, which does only check for the existance of a memory location.
So
> you're probably right about not having to lock an isDefined("") on
> persistant vars.
>
> Thanks,
>
> Robert
>
> -----Original Message-----
> From: Billy Cravens [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, July 31, 2001 10:40 AM
> To: [EMAIL PROTECTED]
> Subject: Re: question.
>
>
> I would agree that a lock is not necessary. However, I'm really not sure
> how CF performs an IsDefined() function. My guess is that somewhere CF
> knows what variables are in existence, and it looks to that memory space -
I
> really don't think it looks at the values, and I seriously doubt it's as
low
> level as the CF structure.
>
> ---
> Billy Cravens
> HR Web Systems, EDS
> [EMAIL PROTECTED]
>
> ----- Original Message -----
> From: "Hinojosa, Robert A" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Tuesday, July 31, 2001 10:07 AM
> Subject: RE: question.
>
>
> > woops, i guess i forgot to paste the code portion of the email. Yes
> billy,
> > definately persistant vars, particularly session vars. I understand the
> > need to lock, but what he is saying is that since your only doing a
lookup
> > in the session structure, you don't need to lock the
> > isDefined("session.var"). Is this a true statement?
> >
> > CODE PORTION OF EMAIL:
> >
> > <cfif IsDefined("Session.MyVar")> <!--- check it exists --->
> > <!--- note: this is longhand as you can read variables in an
> > exclusive --->
> > <!--- lock but for this example a more verbose demonstration is
> > needed --->
> > <!--- read from the variable --->
> > <cflock scope="session" type="readonly" timeout="10">
> > <cfset V_MyVar = Session.MyVar>
> > </cflock>
> > <!--- write to the variable --->
> > <cflock scope="session" type="exclusive" timeout="10">
> > <cfset Session.MyVar = 52>
> > </cflock>
> > </cfif>
> >
> >
> >
> > -----Original Message-----
> > From: Billy Cravens [mailto:[EMAIL PROTECTED]]
> > Sent: Tuesday, July 31, 2001 9:55 AM
> > To: [EMAIL PROTECTED]
> > Subject: Re: question.
> >
> >
> > It may do a read, or it may simply be a pointer to memory where existing
> > variables are defined, with the actual value of the variable in a
> different
> > location.
> >
> > However, I can't understand why you'd need to a lock on a variable read
> > I'm assuming you're referring to locking persistent-scope variables,
like
> > application). The whole purpose of the lock is to ensure data integrity
> > (prevent writing to a variable while another user is reading it).
> However,
> > this shouldn't be the case with reading a variable.
> >
> > ---
> > Billy Cravens
> > HR Web Systems, EDS
> > [EMAIL PROTECTED]
> >
> > ----- Original Message -----
> > From: "Hinojosa, Robert A" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Tuesday, July 31, 2001 9:17 AM
> > Subject: question.
> >
> >
> > > I received this email on another list and I am almost positive he is
> > wrong.
> > > I've read nearly everything there is to know about locking and cf, but
I
> > > wanted to make sure, so I am asking the greats here in this list.
> > Checking
> > > for an isDefined("") is actually doing a type of a read, isn't it, so
> you
> > > would need a lock around it?
> > >
> > > EMAIL:
> > > Just as a quick note, you don't need to lock variables in an
> IsDefined("")
> > > the reason being, you are not reading from it or writing to it....
just
> > > checking its there.....
> > >
> > >
> > > Robert Hinojosa
> > > [EMAIL PROTECTED]
> > > 972.243.4343 x7446
> > >
> > >
> >
>
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