Re: [MSEide-MSEgui-talk] MSElang Objects

2017-06-13 Thread Martin Schreiber 
On Tuesday 13 June 2017 22:29:21 Sieghard wrote:

> Using this as a reference, a syntax like
>
>   MethodType = object function ( or
>   MethodVariable: object function (
> might be considered. Yes, this is more typing.
> (Perhaps abbreviate it with just usind a (leading) period? Like
>  ".function (
What is wrong with "method" instead of "object function"?

>
> [Pascal-ish "with"]
>
> > The problem is that if there are members added to the referenced "with"
> > container they override elements with the same name and type in existing
> > code.
>
> Only if not explicitely qualified - you can always "break out" of the
> current scope using qualifiers. For the current object, the qualifier
> is always "self". And for elements outside of any object context, it is the
> unit name. What's your problem then? and how should the Modula variant be
> better in that respect?
>
Example:
"
unit widgets
interface
type
 pointty = record
  x,y: int32;
 end;

 cwidget = class()
  pos: pointty;
 end;
"

"
unit test
uses
 widgets;

procedure test();
var
 widget: cwidget;
 left: int32;
[...]
 with widget do
  pos.x:= left;
 end;
"

Now the author of the widget library adds a new property to "cwidget"
"
 cwidget = class()
  pos: pointty;
  property left: int32 read pos.x write pos.x;
 end;
"
and brakes the functionality of your "test()" procedure.

Martin

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Re: [MSEide-MSEgui-talk] MSElang Objects

2017-06-13 Thread Martin Schreiber 
On Tuesday 13 June 2017 17:27:41 Edson H wrote:
> Ok. I understand what Martin does. I have implemented this syntax too, in
> my compiler.
>
>
> I just was asking for the keyword ELSIF, to avoid nested IF, for several
> comparisons, but Martin prefers to have a lot of THEN ... END, nested. I
> think the best way is to include ELSIF, to have a clear syntax (like
> Modula-2):
>
>
> IF ... THEN
>
>
> ELSIF ... THEN
>
>
> ELSIF ... THEN
>
>
> END;
>
>
> And that's how it's implemented in my compiler, so it's compatible with
> MSElang, except that MSElang doesn't support ELSIF.
>
It can be added to MSElang too, not yet decided.

Martin

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Re: [MSEide-MSEgui-talk] MSElang Objects

2017-06-13 Thread Sieghard 
Hallo Martin,

Du schriebst am Tue, 13 Jun 2017 06:47:58 +0200:

> > [functions & procedures]
> IIRC you proposed to use "function" for both? Sometimes I have the

No. I did propose to use "function" _only_ if you _insisted_ to use the
same keyword for both uses. If you kept the Pascal convention, only the
better, I will _not_ protest.

["of object"]
> I probably understand wrong, but do "SomeObjectMethod" 
> and "SomeMethodVariable" work with "SomeObject" only? That's not how
> Delphi and MSElang method variables work.

A method variable requires a specific "signature", i.e. parameter list,
which belongs to a method of some specific object type. But I see your case
- for commonly occurring signatures it might be desirable to define such
variables independently of the destination type.
On the other hand, I would really prefer some other syntax than this
appendix, something more in line with the object declaration syntax.
Even the Delphi creators themselves seem not to be happy with it, since
they invented a completely different way for their later introduced "class
methods".
Using this as a reference, a syntax like

  MethodType = object function ( > [WITH]
> > > MSElang provides a safe "with" statement with mandatory local
> > > qualifier.  
> >
> > Something like the "Modula" version?
> > I.e. effectively variable (object) renaming, without opening a new
> > scope?  
> 
> Yes.

[Pascal-ish "with"]
> The problem is that if there are members added to the referenced "with" 
> container they override elements with the same name and type in existing 
> code.

Only if not explicitely qualified - you can always "break out" of the
current scope using qualifiers. For the current object, the qualifier
is always "self". And for elements outside of any object context, it is the
unit name. What's your problem then? and how should the Modula variant be
better in that respect?

> > > [...]
> > > > > It has the advantage that procedure and method names are aligned.
> > > > > More  
> > > >
> > > > That _might_ be a disadvantage at times, as it might make reading
> > > > the source text more difficult.  
> > >
> > > Please explain.  
> >
> > Citing you in
...
> > It looks ugly.
> > "
> > You said.
> >  
> That's not "it might make reading the source text more difficult".

Yes, it is. When something "looks ugly" on first sight, it already _has_
distracted you from understanding what it _means_. You have to concentrate
on the text explicitely to understand it, may be have to read it again. 
And above that, reading a, possibly long, list of all similar looking
lines, it is not so easy to spot changes in those neatly aligned parts.
(Which might be the reason that it "looks ugly".)

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Re: [MSEide-MSEgui-talk] MSElang Objects

2017-06-13 Thread Edson H 
Ok. I understand what Martin does. I have implemented this syntax too, in my 
compiler.


I just was asking for the keyword ELSIF, to avoid nested IF, for several 
comparisons, but Martin prefers to have a lot of THEN ... END, nested. I think 
the best way is to include ELSIF, to have a clear syntax (like Modula-2):


IF ... THEN


ELSIF ... THEN


ELSIF ... THEN


END;


And that's how it's implemented in my compiler, so it's compatible with 
MSElang, except that MSElang doesn't support ELSIF.




De: Marcos Douglas B. Santos 
Enviado: domingo, 11 de junio de 2017 08:11 p.m.
Para: General list for MSEide+MSEgui
Asunto: Re: [MSEide-MSEgui-talk] MSElang Objects


On Sun, Jun 11, 2017 at 4:58 PM, Edson H 
> wrote:

No so much, but In Pascal you need to do:


if ... then
  begin  //WARNING: If use more than a sentence, you need BEGIN-END
...
  end  //DANGER: Don't put semicolon!
else if ... then
  begin  //WARNING: If use more than a sentence, you need BEGIN-END
  ...
  end  //DANGER: Don't put semicolon!
else
  begin  //WARNING: the same before.
   //some code
  end;  //DANGER: Put semicolon!


You're right about classic Pascal. I agree that is ugly.
However, Martin is fixing this, always putting a semicolon no matter what. 
Besides that, the "begin" doesn't exists anymore, just "end". In other words, 
we will always have a "block" using if-then-end instead of if-then-begin-end.

Marcos Douglas
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