1. RE: Changing Euphoria
-------Phoenix-Boundary-07081998-
Hi Shawn Pringle, you wrote on 1/31/02 9:37:11 AM:
>Ofcourse pass by reference is relatively cheap in EUPHORIA, being copy
>on write pointers. It would seem to me that code like:
>list = append(list,a) should be optimized to something like:
>append(!!list,a) keeping with your notation. As, the object passed in
>will be reassigned there is no need to copy a new list in append.
>
>Apparently EUPHORIA already does this, at least for append. The
>documentation says "highly optimized."
>
Built-in functions like append follow their own rules.
If the user writes a function that modifies one of it's
sequence parameters, the sequence is copied before
modification. If the user wants the modification AND a
return value, one or the other must be not passed to the
function or they must be combined into a sequence
(more copying!).
A third reason to add PBR (and slicing shorthands)
to Euphoria is to reduce redundancy:
I have read (and written) too many code lines like:
MOD1_base_elements = doit (MOD1_base_elements[2..MOD1_base_elements])
Much better without the redundancy:
doit (!!MOD1_base_elements[2..])
>As for object orientation, as you said, something like:
> stack.push( 9 )
>would have to be stack = stack.push( 9 ), unless ofcourse we have
>stack=.push(9) for pass by reference like the other = ops.
>
>It may be pass by reference but we still only change things on the left
>side of the "=".
>
Generally, the method dispatch 'stack.push(9)' gets handled as
'push(stack, 9)' i.e. the instance to operate on is passed as a
a hidden parameter. Remember 'stack' here is an instance
(maybe of class STACK?) NOT a class!'.
In Euphoria this is:
1) stack=push(stack,9) -- push() can't return a value
or:
2) push(stack,9) -- stack must at file scope, or unchanged
We could make the rule that class methods can either return a value
OR modify the instance but I would rather make it more general,
especially when PBR brings other advantages.
-------Phoenix-Boundary-07081998---
2. RE: Changing Euphoria
-------Phoenix-Boundary-07081998-
Hi Shawn Pringle, you wrote on 1/29/02 1:30:25 PM:
>
>When it comes to changing something that is so simple and clean I
>cringe. Euphoria was been around a long time with out many changes had
>bugs which must have been many years old. When languages change
>programs break and implementations break. The new bugs might show up in
>the interpreter or the 'compiler'. Many proposed changes are features
>of C that people want in EUPHORIA because they are used to C.
>Things that need features in C are not needed in EUPHORIA:
>
>For Example:
>Pass by reference:
>
>scanf would be something like
>procedure sscanf( sequence str, sequence fmt, sequence& inputs )
>
>On the other hand, in today's EUPHORIA the same thing can be implemented
>with
>function sscanf( sequence str, sequence fmt ) -- return user input
>
>
>Regards,
>Shawn Pringle
>
As I see it, there are 2 advantages to pass-by-reference:
1) More efficient.
foo = modify(foo) -- involves a couple of copy operations
modify (!!foo) -- modifies in place (my pass-by-reference syntax)
2) Object orientation
Methods are automatically passed the instance they are
to work on ('this') as the first parameter. Methods which
modify the instance and also return a value are extremely
awkward without 'this' beng passed by reference.
It adds complexity and power, but it does indeed compromise the
simplicity that makes Euphoria so attractive.
Karl Bochert
-------Phoenix-Boundary-07081998---
3. RE: Changing Euphoria
Ofcourse pass by reference is relatively cheap in EUPHORIA, being copy
on write pointers. It would seem to me that code like:
list = append(list,a) should be optimized to something like:
append(!!list,a) keeping with your notation. As, the object passed in
will be reassigned there is no need to copy a new list in append.
Apparently EUPHORIA already does this, at least for append. The
documentation says "highly optimized."
As for object orientation, as you said, something like:
stack.push( 9 )
would have to be stack = stack.push( 9 ), unless ofcourse we have
stack=.push(9) for pass by reference like the other = ops.
It may be pass by reference but we still only change things on the left
side of the "=".
It sounds like we are designing a EUPHORIA++ here.
Cheers!
Shawn
kbochert at ix.netcom.com wrote:
> -------Phoenix-Boundary-07081998-
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> Content-transfer-encoding: 8bit
>
> Hi Shawn Pringle, you wrote on 1/29/02 1:30:25 PM:
>
> >
> >When it comes to changing something that is so simple and clean I
> >cringe. Euphoria was been around a long time with out many changes had
> >bugs which must have been many years old. When languages change
> >programs break and implementations break. The new bugs might show up in
> >the interpreter or the 'compiler'. Many proposed changes are features
> >of C that people want in EUPHORIA because they are used to C.
> >Things that need features in C are not needed in EUPHORIA:
> >
> >For Example:
> >Pass by reference:
> >
> >scanf would be something like
> >procedure sscanf( sequence str, sequence fmt, sequence& inputs )
> >
> >On the other hand, in today's EUPHORIA the same thing can be implemented
> >with
> >function sscanf( sequence str, sequence fmt ) -- return user input
> >
> >
> >Regards,
> >Shawn Pringle
> >
> As I see it, there are 2 advantages to pass-by-reference:
>
> 1) More efficient.
> foo = modify(foo) -- involves a couple of copy operations
> modify (!!foo) -- modifies in place (my pass-by-reference syntax)
>
> 2) Object orientation
> Methods are automatically passed the instance they are
> to work on ('this') as the first parameter. Methods which
> modify the instance and also return a value are extremely
> awkward without 'this' beng passed by reference.
>
> It adds complexity and power, but it does indeed compromise the
> simplicity that makes Euphoria so attractive.
>
> Karl Bochert
>
>
> -------Phoenix-Boundary-07081998---
>
Regards,
Shawn Pringle
