variables and objects
erik hansen
erikhans08 at yahoo.com
Wed Feb 26 02:07:02 EST 2003
--- Jan Schenkel <janschenkel at yahoo.com> wrote:
> --- erik hansen <erikhans08 at yahoo.com> wrote:
> > --- Jan Schenkel <janschenkel at yahoo.com>
> wrote:
> > > --- "Ivers, Doug E" <Doug_Ivers at lord.com>
> > > wrote:
> > > > Seems that all user-created variables are
> > > character
> > > > strings. Is target also a character
> string,
> > > or is
> > > > it something more sophisticated (like a
> > > pointer in
> > > > C)? Same question for this card, recent
> > > card, this
> > > > stack, etc.
> > > >
> > > > Are these statements the same in the way
> they
> > > work
> > > > "behind the scenes"?
> > > > answer the id of this card
> > > > get the long name of this card;
> > > > answer the id of it
> >
> > > All variables are indeed character strings
> ;
> > > including
> > > 'the target' ; however, the engine
> recognises
> > > certain
> > > keywords and can grab the data without
> having
> > > to parse
> > > the content of the variable first ; so in
> your
> > > example, "the id of this card" will work
> faster
> > > than
> > > "the id of it" because the engine grabs it
> > > directly.
> >
> > the engine grabs <it> or grabs "this card"?
> >
>
> Hi Erik,
>
> You're right, that was a bit less-than-stellar
> choice
> of words upon review.
>
> "answer the id of this card" takes the engine a
> single
> step to retrieve the ID.
>
> "get the long name of this card; answer the id
> of it"
> actually takes 5 steps :
> 1) retrieve the long name of this card
> 2) stuff it down the special variable 'it'
> 3) retrieve the content of the special variable
> 'it'
> 4) parse that content for an object reference
> 5) retrieve the id of said object
>
> "put the long name of this card into tLongName
> ;
> answer the id of tLongName" would have been the
> slowest variant, because the engine recognises
> the
> special variable 'it' and doesn't have to dig
> through
> memory references to find out which bit of RAM
> you're
> referring to.
>
> This sort of information can be used to
> optimise
> performance of certain key areas of your
> program. One
> example of this is the recent thread on
> imageData
> manipulation, where the re-use of local
> variables
> instead of reading the imageData again and
> again,
> turned an effect from sluggish to smooth.
>
> Then again, the point is moot if your program
> does
> what it has to do and runs at acceptable speeds
> on
> your machine.
>
> Hope this cleared a few things up,
>
> Jan Schenkel.
>
thanks this is good to know.
i felt like a little snot as soon as i clicked on
the send button. the nice thing about paper and
calligraphy pens was that you put the letter in a
drawer over night, then decided whether you
really wanted to inflict it on the world.
=====
erik at erikhansen.org http://www.erikhansen.org
__________________________________________________
Do you Yahoo!?
Yahoo! Tax Center - forms, calculators, tips, more
http://taxes.yahoo.com/
More information about the use-livecode
mailing list