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Language translation

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  Language translation Anthony Williams <awgold70@gmail.com> - 2014-03-05 06:27 -0800
    Re: Language translation Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2014-03-05 16:42 +0100
    Re: Language translation Kaz Kylheku <kaz@kylheku.com> - 2014-03-05 16:08 +0000
    Re: Language translation Jens Kallup <jkallup@web.de> - 2014-03-06 20:31 +0100
    Re: Language translation Nor Jaidi Tuah <norjaidi.tuah@ubd.edu.bn> - 2014-03-10 08:37 +0800
      Re: Language translation Anthony Williams <awgold70@gmail.com> - 2014-03-10 10:23 -0700

#1131 — Language translation

Dear Group,

I'm facing the problem to translate language A into language B. The
problem is, that A is an object oriented language (it supports
classes, attributes of classes ...).  But B is much simpler. It hasn't
support for classes. There is only variables, functions.  And my
Question: How Could I Implement Classes in B. (At first it would be
sufficient, if i could "emulate" simple classes, that don't support
inheritance, function hiding, polymorphy ...)

Thank you for your answer,
A.W.
[This is basicallly what compilers for OOP languages do -- they
translate the OOP stuff into equivalent code for a much lower level
language, typically assembler or machine language.  There are fairly
standard ways to do low level implemenations of OOP, with a tree of
structures for each class with pointers to all of the class
structures, and each class instance having a structure with a field
for each data member and a pointer back to its class structure, with
more or less extra stuff depending on how complex the inheritance
system is.  So you have to do that in language B.  If this sounds
really tedious, yes, it is. -John]

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#1132

Anthony Williams schrieb:
> Dear Group,
>
> I'm facing the problem to translate language A into language B. The
> problem is, that A is an object oriented language (it supports
> classes, attributes of classes ...).  But B is much simpler. It hasn't
> support for classes. There is only variables, functions.  And my
> Question: How Could I Implement Classes in B. (At first it would be
> sufficient, if i could "emulate" simple classes, that don't support
> inheritance, function hiding, polymorphy ...)

Just rephrasing what John said, in my own words and view:

An emulation typically adds an this/self instance reference to the
parameter list of every method. "Real" OO languages simply hide this
parameter in the source code, i.e. the compiler changes the parameter
list and calls accordingly. That's what your translator should add to
the translated source code. That's all about basic (static) methods.

Instance data is a record (struct...), containing all data fields of the
class.

BTW the first C++ compiler was such a translator, from C++ to C. I don't
remember its name, but it should be available in the museum - John?

DoDi
[cfront which you can find at http://www.softwarepreservation.org/projects/c_plus_plus
-John]

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#1133

On 2014-03-05, Anthony Williams <awgold70@gmail.com> wrote:
> Dear Group,
>
> I'm facing the problem to translate language A into language B. The
> problem is, that A is an object oriented language (it supports
> classes, attributes of classes ...).  But B is much simpler. It hasn't
> support for classes. There is only variables, functions.  And my
> Question: How Could I Implement Classes in B. ...

It may not be possible if language B doesn't have things like pointers,
aggregate types such as vectors, or function indirection.

This question is too vague in its current form, lacking a detailed
specification of A and B.

[Of course it's possible unless the language is weaker than Tiny
Basic.  But it might be really ugly, e.g., parallel arrays to simulate
structures and glue functions that dispatch on an index parameter to
sort of fake function pointers.  Like I said, it's tedious. -John]

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#1134

Hello,

for my compiler, i do some test's.
when i had a class "Aclass", then i check it's parent.
It can be "Acustom", or an other class "Aform".

So, i have 2 types:

Acustom // parent (super)
Aclass  // my plain class

Acustom  // parent (super)
Aform    // form class (window)
Aclass   // class -> Aform = parent

You can build a tree:

CLASS Aform  // you can leave the parent, if you know it is Acustom
...
ENDCLASS


CLASS Aclass OF Aform
...
ENDCLASS


Then you can build code:
(All classes becomes numbers - you reserve a part
for your static parents...)

push 10    ; push 10 (Aform - if you wish it is a window)
push 0     ; parent (window) class
push CNAME ; rtti - name the class

call create_class  ; call function to create the class
                    ; e.g. init window size


The best way is, you should consult the assembler code,
which is created by follpwing command:

gcc -S test.cc

cheers
Jens

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#1139

May I suggest you look at Vala (https://wiki.gnome.org/Projects/Vala)
an OO language that compiles to C. The C code it produces is fairly
human readable except for the heavy use of temp variables. Though Vala
is intended to be used with GObject (a library to support
object-orientation in C), it can be used without it.

Nice day
Nor Jaidi Tuah

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#1140

Thanx to all for your answers.
This brings me closer to the thing :-)

Best regards,
A.W.



Nor Jaidi Tuah wrote:
> May I suggest you look at Vala (https://wiki.gnome.org/Projects/Vala)
> an OO language that compiles to C. The C code it produces is fairly
> human readable except for the heavy use of temp variables. Though Vala
> is intended to be used with GObject (a library to support
> object-orientation in C), it can be used without it.

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