1. RE: if statement not working
xxmyt at yahoo.com wrote:
> hello everyone.
>
> the code i pasted down works properly. however, it doesnt work in the
> second way.
>
> my code:
> include dos32lib.e
> without warning
>
> constant
> Win = create( Window, "PASSWORD REQUIRED", 0, Default, Default,
> 400, 200, 0 ),
>
> Sle1 = create( EditText, "", Win, 10, 40, 120, 20, 0 ),
> Button1 = create( PushButton, "OK", Win, 180, 40, 120, 20, 0 )
>
>
> procedure onClick_Button1()
>
> if equal(getText(Sle1),"YES") then
> closeWindow(Win)
> end if
>
> end procedure
>
> onClick[Button1] = routine_id("onClick_Button1")
>
> WinMain( Win )
>
> but if i change the if statement this way, i get an error message:
>
> if getText(Sle1) = "YES" then
> closeWindow(Win)
> end if
>
> error message says, the result of the if statemnt should be an atom.
>
> so whats it all about?
>
It means to compare sequences, and therefore any string, you have to use
the "equal" or "compare" statements, not = < > !=.
Using the latter operators on a sequence is for expressions, and
compares each element of a sequence to its counterpart in another
sequence of equal length. For instance,
s = {8,9,10} = {8,4,10}
Now s is {1,0,1}.
This facility is very useful, but can make if statements involving
sequences a bit non-intuitive. Anyway, you gotta use equal & compare..
2. RE: if statement not working
- Posted by bensler at mail.com
Mar 21, 2002
xxmyt at yahoo.com wrote:
> hello everyone.
>
> the code i pasted down works properly. however, it doesnt work in the
> second way.
>
> my code:
> include dos32lib.e
> without warning
>
> constant
> Win = create( Window, "PASSWORD REQUIRED", 0, Default, Default,
> 400, 200, 0 ),
>
> Sle1 = create( EditText, "", Win, 10, 40, 120, 20, 0 ),
> Button1 = create( PushButton, "OK", Win, 180, 40, 120, 20, 0 )
>
>
> procedure onClick_Button1()
>
> if equal(getText(Sle1),"YES") then
> closeWindow(Win)
> end if
>
> end procedure
>
> onClick[Button1] = routine_id("onClick_Button1")
>
> WinMain( Win )
>
> but if i change the if statement this way, i get an error message:
>
> if getText(Sle1) = "YES" then
> closeWindow(Win)
> end if
>
> error message says, the result of the if statemnt should be an atom.
>
> so whats it all about?
In oder to compare two objects, which are not both atoms, you must use
equal().
if equal(getText(Sle1),"YES") then
closeWindow(Win)
end if
Chris
3. RE: if statement not working
- Posted by bensler at mail.com
Mar 21, 2002
Sorry, I misunderstood the question. :P
I like the fact that = only works for numeric comparison.
I'd like to see == for object comparisons though, instead of equal()
Chris
xxmyt at yahoo.com wrote:
> hello everyone.
>
> the code i pasted down works properly. however, it doesnt work in the
> second way.
>
> my code:
> include dos32lib.e
> without warning
>
> constant
> Win = create( Window, "PASSWORD REQUIRED", 0, Default, Default,
> 400, 200, 0 ),
>
> Sle1 = create( EditText, "", Win, 10, 40, 120, 20, 0 ),
> Button1 = create( PushButton, "OK", Win, 180, 40, 120, 20, 0 )
>
>
> procedure onClick_Button1()
>
> if equal(getText(Sle1),"YES") then
> closeWindow(Win)
> end if
>
> end procedure
>
> onClick[Button1] = routine_id("onClick_Button1")
>
> WinMain( Win )
>
> but if i change the if statement this way, i get an error message:
>
> if getText(Sle1) = "YES" then
> closeWindow(Win)
> end if
>
> error message says, the result of the if statemnt should be an atom.
>
> so whats it all about?
>
>
>
4. RE: if statement not working
- Posted by bensler at mail.com
Mar 21, 2002
Andy Serpa wrote:
>
> xxmyt at yahoo.com wrote:
> > hello everyone.
> >
> > the code i pasted down works properly. however, it doesnt work in the
> > second way.
> >
> > my code:
> > include dos32lib.e
> > without warning
> >
> > constant
> > Win = create( Window, "PASSWORD REQUIRED", 0, Default, Default,
> > 400, 200, 0 ),
> >
> > Sle1 = create( EditText, "", Win, 10, 40, 120, 20, 0 ),
> > Button1 = create( PushButton, "OK", Win, 180, 40, 120, 20, 0 )
> >
> >
> > procedure onClick_Button1()
> >
> > if equal(getText(Sle1),"YES") then
> > closeWindow(Win)
> > end if
> >
> > end procedure
> >
> > onClick[Button1] = routine_id("onClick_Button1")
> >
> > WinMain( Win )
> >
> > but if i change the if statement this way, i get an error message:
> >
> > if getText(Sle1) = "YES" then
> > closeWindow(Win)
> > end if
> >
> > error message says, the result of the if statemnt should be an atom.
> >
> > so whats it all about?
> >
>
> It means to compare sequences, and therefore any string, you have to use
>
> the "equal" or "compare" statements, not = < > !=.
>
> Using the latter operators on a sequence is for expressions, and
> compares each element of a sequence to its counterpart in another
> sequence of equal length. For instance,
>
> s = {8,9,10} = {8,4,10}
>
> Now s is {1,0,1}.
>
> This facility is very useful, but can make if statements involving
> sequences a bit non-intuitive. Anyway, you gotta use equal & compare..
>
Could you give an example of how that might be useful?
I understand the concept, but I can't wrap my brain around how I could
use it.
btw:
That assignment statement is easier to understand if written:
s = ({8,9,10} = {8,4,10})
Chris
5. RE: if statement not working
- Posted by bensler at mail.com
Mar 21, 2002
Good point.
I have never found the need to use compare, so I was thinking in a
narrower spectrum when I mentioned ==.
I see two benefits to the current syntax.
1. comparing equal length sequences (does the entire structure of the
sequence need to match, or just the length?)
2. to visually define the difference between a numeric compare, and an
object compare.
See: "justifying compare" posted by David Cuny in 1998
Chris
Derek Parnell wrote:
>
> This, in my not so humble opinion, is one of RDS's lesser decisions.
>
> For some reason, not quiet explained yet, RDS decided that sequences
> must not allowed to be compared
> using the normal comparision operators. For sequences you are forced
> into calling a function to
> compare them. The two main functions are 'compare()' and 'equal()'.
>
> compare(s1,s2) returns one of three values:
> -1 if s1 is less than s2
> 0 if s1 equals s2
> 1 if s1 is greater than s2
>
> equal(s1,s2) returns one of two values:
> 0 if s1 is not equal to s2
> 1 if s1 is equal to s2
>
> Go figure! Many people have been try to get RDS to see sense in using
> the standard comparision
> operators with sequences but to no avail yet.
>
> -------
> Derek.
>
> 22/03/2002 11:04:33 AM, xxmyt at yahoo.com wrote:
>
> >
> >hello everyone.
> >
> >the code i pasted down works properly. however, it doesnt work in the
> >second way.
> >
> >my code:
> >include dos32lib.e
> >without warning
> >
> >constant
> > Win = create( Window, "PASSWORD REQUIRED", 0, Default, Default,
> >400, 200, 0 ),
> >
> > Sle1 = create( EditText, "", Win, 10, 40, 120, 20, 0 ),
> > Button1 = create( PushButton, "OK", Win, 180, 40, 120, 20, 0 )
> >
> >
> >procedure onClick_Button1()
> >
> > if equal(getText(Sle1),"YES") then
> > closeWindow(Win)
> > end if
> >
> >end procedure
> >
> >onClick[Button1] = routine_id("onClick_Button1")
> >
> >WinMain( Win )
> >
> > but if i change the if statement this way, i get an error message:
> >
> > if getText(Sle1) = "YES" then
> > closeWindow(Win)
> > end if
> >
> >error message says, the result of the if statemnt should be an atom.
> >
> >so whats it all about?
> >
> >
> ---------
> Cheers,
> Derek Parnell
> ICQ# 7647806
>
>
6. RE: if statement not working
bensler at mail.com wrote:
> Andy Serpa wrote:
> >
<snip>
> >
> > s = {8,9,10} = {8,4,10}
> >
> > Now s is {1,0,1}.
> >
> > This facility is very useful, but can make if statements involving
> > sequences a bit non-intuitive. Anyway, you gotta use equal & compare..
> >
>
> Could you give an example of how that might be useful?
> I understand the concept, but I can't wrap my brain around how I could
> use it.
>
I use it mainly in AI stuff where I need to work on binary strings in an
explicit manner.
I also use it a lot for stuff like this:
x = {10,20,30,40,50,60}
y = {30,10,25,40,60,65}
z = (x < y)*x + (y <= x)*y
z is now: {10,10,25,40,50,60}
(taking the smaller element from each sequence -- the "=" is in the
second half but not the first so equal elements will only be taken once)
Yep, it's useful.
7. Re: RE: if statement not working
22/03/2002 12:43:00 PM, bensler at mail.com wrote:
>
>I like the fact that = only works for numeric comparison.
>I'd like to see == for object comparisons though, instead of equal()
>
>Chris
Why? What problem is having two sets of comparitors solve?
Are you suggesting for numbers we use: = > < != <= >=
and for sequences we use: == >> << !== <== >==
If want to know if one sequence has the same value as another, why is it better
that I use "=="
instead of "="?
It even introduces another issue that the current Euphoria doesn't have.
Currently I can write:
atom x
sequence s
if equal(x,s) then ...
but your suggestion I'd use:
if x == s then ...
but what happens if I later change my mind and 's' is now an integer. I have to
go and update all my
comparitor references to use '=' etc... Is this a better idea? I think not.
---------
Derek.
8. RE: if statement not working
- Posted by bensler at mail.com
Mar 21, 2002
Refer to the "[If/then and sequences...]" thread from Aug 2000
or the "Comparing Sequences" thread from Oct 2000
Chris
Derek Parnell wrote:
>
> This, in my not so humble opinion, is one of RDS's lesser decisions.
>
> For some reason, not quiet explained yet, RDS decided that sequences
> must not allowed to be compared
> using the normal comparision operators. For sequences you are forced
> into calling a function to
> compare them. The two main functions are 'compare()' and 'equal()'.
>
> compare(s1,s2) returns one of three values:
> -1 if s1 is less than s2
> 0 if s1 equals s2
> 1 if s1 is greater than s2
>
> equal(s1,s2) returns one of two values:
> 0 if s1 is not equal to s2
> 1 if s1 is equal to s2
>
> Go figure! Many people have been try to get RDS to see sense in using
> the standard comparision
> operators with sequences but to no avail yet.
>
> -------
> Derek.
>
> 22/03/2002 11:04:33 AM, xxmyt at yahoo.com wrote:
>
> >
> >hello everyone.
> >
> >the code i pasted down works properly. however, it doesnt work in the
> >second way.
> >
> >my code:
> >include dos32lib.e
> >without warning
> >
> >constant
> > Win = create( Window, "PASSWORD REQUIRED", 0, Default, Default,
> >400, 200, 0 ),
> >
> > Sle1 = create( EditText, "", Win, 10, 40, 120, 20, 0 ),
> > Button1 = create( PushButton, "OK", Win, 180, 40, 120, 20, 0 )
> >
> >
> >procedure onClick_Button1()
> >
> > if equal(getText(Sle1),"YES") then
> > closeWindow(Win)
> > end if
> >
> >end procedure
> >
> >onClick[Button1] = routine_id("onClick_Button1")
> >
> >WinMain( Win )
> >
> > but if i change the if statement this way, i get an error message:
> >
> > if getText(Sle1) = "YES" then
> > closeWindow(Win)
> > end if
> >
> >error message says, the result of the if statemnt should be an atom.
> >
> >so whats it all about?
> >
> >
> ---------
> Cheers,
> Derek Parnell
> ICQ# 7647806
>
>
9. Re: RE: if statement not working
22/03/2002 2:19:34 PM, bensler at mail.com wrote:
>
>Good point.
>
>I have never found the need to use compare, so I was thinking in a
>narrower spectrum when I mentioned ==.
>
>I see two benefits to the current syntax.
>
>1. comparing equal length sequences (does the entire structure of the
>sequence need to match, or just the length?)
>
I am talking about language syntax, not implementation tactics. Is there any
reason that the
interpreter cannot compare lengths if it sees '=' instead of 'compare()'?
>2. to visually define the difference between a numeric compare, and an
>object compare.
Have you actually needed to do this? Anyone?
>See: "justifying compare" posted by David Cuny in 1998
I will. David is very good, but I'm not convinced yet. Keep trying 
---------
Cheers,
Derek Parnell
ICQ# 7647806
10. RE: if statement not working
On 22 Mar 2002, at 4:10, bensler at mail.com wrote:
>
> Refer to the "[If/then and sequences...]" thread from Aug 2000
> or the "Comparing Sequences" thread from Oct 2000
How about it, Karl, a fall-thru the "=" to the equal()?
Kat
> Chris
>
> Derek Parnell wrote:
> >
> > This, in my not so humble opinion, is one of RDS's lesser decisions.
> >
> > For some reason, not quiet explained yet, RDS decided that sequences
> > must not allowed to be compared
> > using the normal comparision operators. For sequences you are forced
> > into calling a function to
> > compare them. The two main functions are 'compare()' and 'equal()'.
> >
> > compare(s1,s2) returns one of three values:
> > -1 if s1 is less than s2
> > 0 if s1 equals s2
> > 1 if s1 is greater than s2
> >
> > equal(s1,s2) returns one of two values:
> > 0 if s1 is not equal to s2
> > 1 if s1 is equal to s2
> >
> > Go figure! Many people have been try to get RDS to see sense in using
> > the standard comparision
> > operators with sequences but to no avail yet.
> >
> > -------
> > Derek.
> >
> > 22/03/2002 11:04:33 AM, xxmyt at yahoo.com wrote:
> >
> > >
> > >hello everyone.
> > >
> > >the code i pasted down works properly. however, it doesnt work in the
> > >second way.
> > >
> > >my code:
> > >include dos32lib.e
> > >without warning
> > >
> > >constant
> > > Win = create( Window, "PASSWORD REQUIRED", 0, Default, Default,
> > >400, 200, 0 ),
> > >
> > > Sle1 = create( EditText, "", Win, 10, 40, 120, 20, 0 ),
> > > Button1 = create( PushButton, "OK", Win, 180, 40, 120, 20, 0 )
> > >
> > >
> > >procedure onClick_Button1()
> > >
> > > if equal(getText(Sle1),"YES") then
> > > closeWindow(Win)
> > > end if
> > >
> > >end procedure
> > >
> > >onClick[Button1] = routine_id("onClick_Button1")
> > >
> > >WinMain( Win )
> > >
> > > but if i change the if statement this way, i get an error message:
> > >
> > > if getText(Sle1) = "YES" then
> > > closeWindow(Win)
> > > end if
> > >
> > >error message says, the result of the if statemnt should be an atom.
> > >
> > >so whats it all about?
> > >
> > >
> > ---------
> > Cheers,
> > Derek Parnell
> > ICQ# 7647806
> >
> >
>
>
>
>
>
11. RE: if statement not working
- Posted by bensler at mail.com
Mar 21, 2002
equal() us just a derivitive of compare()
function equal(object a, object b)
return not compare(a,b)
end function
every relational operator can be mapped directly to compare().
a =b : compare(a,b) =0
a!=b : compare(a,b) !=0
a <b : compare(a,b) <0
a>=b : compare(a,b) >=0
etc...
refer specifically to Derek Parnell's post "Re:[If/then and
sequences...]"
Chris
Kat wrote:
> On 22 Mar 2002, at 4:10, bensler at mail.com wrote:
>
> >
> > Refer to the "[If/then and sequences...]" thread from Aug 2000
> > or the "Comparing Sequences" thread from Oct 2000
>
> How about it, Karl, a fall-thru the "=" to the equal()?
>
> Kat
>
> > Chris
> >
> > Derek Parnell wrote:
> > >
> > > This, in my not so humble opinion, is one of RDS's lesser decisions.
> > >
> > > For some reason, not quiet explained yet, RDS decided that sequences
> > > must not allowed to be compared
> > > using the normal comparision operators. For sequences you are forced
> > > into calling a function to
> > > compare them. The two main functions are 'compare()' and 'equal()'.
> > >
> > > compare(s1,s2) returns one of three values:
> > > -1 if s1 is less than s2
> > > 0 if s1 equals s2
> > > 1 if s1 is greater than s2
> > >
> > > equal(s1,s2) returns one of two values:
> > > 0 if s1 is not equal to s2
> > > 1 if s1 is equal to s2
> > >
> > > Go figure! Many people have been try to get RDS to see sense in using
> > > the standard comparision
> > > operators with sequences but to no avail yet.
> > >
> > > -------
> > > Derek.
> > >
> > > 22/03/2002 11:04:33 AM, xxmyt at yahoo.com wrote:
> > >
> > > >
> > > >hello everyone.
> > > >
> > > >the code i pasted down works properly. however, it doesnt work in the
> > > >second way.
> > > >
> > > >my code:
> > > >include dos32lib.e
> > > >without warning
> > > >
> > > >constant
> > > > Win = create( Window, "PASSWORD REQUIRED", 0, Default, Default,
> > > >400, 200, 0 ),
> > > >
> > > > Sle1 = create( EditText, "", Win, 10, 40, 120, 20, 0 ),
> > > > Button1 = create( PushButton, "OK", Win, 180, 40, 120, 20, 0 )
> > > >
> > > >
> > > >procedure onClick_Button1()
> > > >
> > > > if equal(getText(Sle1),"YES") then
> > > > closeWindow(Win)
> > > > end if
> > > >
> > > >end procedure
> > > >
> > > >onClick[Button1] = routine_id("onClick_Button1")
> > > >
> > > >WinMain( Win )
> > > >
> > > > but if i change the if statement this way, i get an error message:
> > > >
> > > > if getText(Sle1) = "YES" then
> > > > closeWindow(Win)
> > > > end if
> > > >
> > > >error message says, the result of the if statemnt should be an atom.
> > > >
> > > >so whats it all about?
> > > >
> > > >
> > > ---------
> > > Cheers,
> > > Derek Parnell
> > > ICQ# 7647806
> > >
> > >
12. RE: if statement not working
- Posted by bensler at mail.com
Mar 22, 2002
Graeme wrote:
>
> >I just tripped against this stupid restriction again last night. I've
> written a function called
> >begins() to help me out, but it ain't pretty.
> >
> > if begins(s, t) then ...
> >
> >I originally wrote:
> >
> > if equal(s[1..length(t)], t) then ...
> >
> >but this fails whenever s is shorter than t.
>
>
> Yeah, and I hate having to press enter at the end of the
> line, it really annoys me. Rob can you fix this or I want my
> money back.....
>
>
> But seriously, having the interpreter return a valid result
> from accessing non-existant data is just way stupid.
>
>
> Graeme
I agree with Graeme on this one :P
Here is a function that I sometimes use for formatting sequences.
function format(sequence s, sequence form)
if length(s) < length(form) then
return s & form[length(s)+1..length(form)]
elsif length(s) > length(form) then
return s[1..length(form)]
end if
return s
end function
Dereks problem would be written:
if equal(format(s,t),t) then ...
(I'd much rather write: if format(s,t) = t then ... )
In particular, I find it handy for declaring my routines like this:
procedure foo(sequence args)
args = format(args,{1,0,{},"none"})
etc...
end procedure
This allows the routine to be called with a dynamic number of arguments.
If some of the trailing arguments are omitted, they are appended using
the defaults.
This also lends to expandability, and a bunch of other convenient
things.
Chris
13. RE: if statement not working
- Posted by bensler at mail.com
Mar 22, 2002
Graeme wrote:
>
> >I just tripped against this stupid restriction again last night. I've
> written a function called
> >begins() to help me out, but it ain't pretty.
> >
> > if begins(s, t) then ...
> >
> >I originally wrote:
> >
> > if equal(s[1..length(t)], t) then ...
> >
> >but this fails whenever s is shorter than t.
>
>
> Yeah, and I hate having to press enter at the end of the
> line, it really annoys me. Rob can you fix this or I want my
> money back.....
If yer gonna ask for something silly, it should at least NOT be
implemented already :P
The only reason you have to press enter is because your editor limits
you. Euphoria will accept any file regardless of line feeds and carriage
returns, as long as each statement is separated with whitespace.
I compacted my minesweeper source code (@ 15,000 bytes) into a single
line, and executed it.
Chris
14. RE: if statement not working
- Posted by bensler at mail.com
Mar 22, 2002
Kat wrote:
> On 22 Mar 2002, at 23:24, Derek Parnell wrote:
>
> >
> > ----- Original Message -----
> > From: "Graeme" <graemeburke at hotmail.com>
> > To: "EUforum" <EUforum at topica.com>
> > Sent: Friday, March 22, 2002 7:20 PM
> > Subject: Re: if statement not working
> >
> >
> > > >I just tripped against this stupid restriction again last night. I've
> > > written a function called
> > > >begins() to help me out, but it ain't pretty.
> > > >
> > > > if begins(s, t) then ...
> > > >
> > > >I originally wrote:
> > > >
> > > > if equal(s[1..length(t)], t) then ...
> > > >
> > > >but this fails whenever s is shorter than t.
> > >
> > >
> > > Yeah, and I hate having to press enter at the end of the
> > > line, it really annoys me. Rob can you fix this or I want my
> > > money back.....
> > >
> >
> > Thanks for those encouraging words. I feel much better now that I
> > realise I must
> > not desecrate the temple of Euphoria.
> >
> > > But seriously, having the interpreter return a valid result
> > > from accessing non-existant data is just way stupid.
> > >
> >
> > Graeme, you are absolutely correct.
>
> So if i were to ask you to return all 100K bytes of this email, you'd
> land in a
> mental institution? Eu would, figuratively speaking.
>
> Kat
>
That's not natural behaviour.
When you tell me to to return 100kb of this file, I'll tell you it's not
100kb.
I won't give you the file padded with.. what SHOULD it be padded with?
If you told me to give you 100kb of this file, or whatever I can if it's
not that big, then I would give you about 10kb of data.
If you told me I MUST return 100kb from this file, I would then proceed
to ask what I should append to the data.
Chris
15. RE: if statement not working
David Cuny wrote:
> rforno wrote:
>
> > if s[1..2] = "/*" then ...
> > could never work fine. It gives an error message telling conditions must
> > be
> > atoms.
>
> Yes, and that's perhaps the most suprising bit of all. You'd sort of
> expect
> that with an emphasis on being orthagonal, the 'if' would accept {0, 0}
> as
> false, and { 0, 1 } as true.
Well, I'm kinda late into this thread, but I have to ask:
Why would {0,1} be logically assumed to be true? I can't think of
any reason for it to be seen as such that's obviously superior
to all the reasons why it should be seen as false, or as invalid.
(Serious question there. If there's some reason I'm missing, I'd
be interested in hearing it, as the concept might have value in
several places.)
As of right now, I think having a sequence not be accepted as a
statement of truth or falsehood makes sense; that being the case,
a function like 'equal' becomes required to compare slices/strings.
With THAT being the case, a large portion of this thread becomes
moot, yes?
Rod Jackson
16. RE: if statement not working
Graeme wrote:
> At 06:10 PM 3/22/02 -0600, Kat wrote:
>
> >
> >So stop with the padding already! When can i expect that $30?
> >
>
> so if s="hello"
>
> s[2..4] is "ell"
> s[-1..2] is "he"
> s[5..6] is "o"
> and s[34..39] is {}
>
>
> interesting idea.
> I still dont like it that much...
Ditto. I think many are forgetting that we're not really
talking just about the 'if' statement here, but rather how
subscripting operates as an expression. Euphoria spends, I
would imagine, a bit of time during runtime making sure you
don't try to access an invalid index. The safety of that
implementation is supposed to be a selling point. Now,
suddenly, ALL indices should be valid for EVERY sequence?
Is that *really* what we want?
Rod Jackson
