Hi,
I'm forwarding a message from Przemek on this matter.
---------- Forwarded message ----------
From: Przemyslaw Czerpak <dru...@acn.waw.pl>
Date: Wed, Mar 11, 2009 at 4:01 PM
Subject: Re: [xHarbour-developers] Upper() and codepage.
To: Phil Krylov <p...@newstar.rinet.ru>
On Wed, 11 Mar 2009, Phil Krylov wrote:
> > In my test, Clipper did NOT optimize at all, Upper()/Lower()/Asc()/Chr().
> > Here is my simple test:
> > PROCEDURE Main()
> > LOCAL c1 := Upper( "Hello" ), c2 := Lower( "World" )
> > LOCAL c3 := Chr( 65 )
> > LOCAL n1 := Asc( "A" )
> add here: c3 := Upper("hello2" + Chr(97))
> > ? c1, c2, c3, n1
> > RETURN
> By observing the obj file, you can find the string "HELLO3A", so it
> looks like Clipper does not optimize Upper in LOCAL declarations, but
> optimizes the non-LOCAL occurence. (and optimizes Chr there. However,
> I can't easily read Clipper PCODE from binary files and so can't tell
> if Chr is optimized in LOCAL declarations.).
> As for the LOWER, AFAIR it was never optimized.
In Clipper in few places programmers forgot to add call to
expression_reduce() or similar function which in Clipper
reduce expressions.
One of such places is expression used for LOCAL initialization but
there are also others like object expression when method is sent:
<objExp> : msg()
<objExp> is not optimized. Make some tests and you will find also
others non optimized expressions.
Try this example:
PROCEDURE Main()
LOCAL l1 := Upper( "Hello" )
LOCAL l2 := Lower( "World" )
LOCAL l3 := Chr( 65 )
LOCAL l4 := Asc( "A" )
LOCAL l5 := 1 == 1
? l1, l2, l3, l4, l5
l1 := Upper( "Hello" )
l2 := Lower( "World" )
l3 := Chr( 65 )
l4 := Asc( "A" )
l5 := 1 == 1
? l1, l2, l3, l4, l5
RETURN
For optimization tests I suggest to use static initialization, f.e.:
proc main()
static s := upper( "abc" + chr( 122 ) )
? s
return
If you remove UPPER() optimization xHarbour will not be able to compile
above code.
BTW the recent modifications for RESTORE FROM * are also wrong.
Here is the example which illustrates that it's general memvar
clear issue and how it should work with getlist overloaded by
private variable.
memvar getlist
proc main()
getlist:="public:getlist"
? getlist
private getlist:="private:getlist"
? getlist
CLEAR MEMORY
? getlist
return
Compile it with Clipper or current Harbour to see expected results.
Then try xHarbour.
best regards,
Przemek
--
С уважением,
Филипп Крылов.
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