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D - explicit out / inout - C# ... grrr

reply "Matthew Wilson" <matthew stlsoft.org> writes:
Well sorry to do this, chaps, but I think I'm coming to the conclusion that

within the calling code. It's just too ambiguous otherwise. I'm working away
on the reg stuff, and marking certain things out as appropriate, but then
having to jump back and forth for the declarations.

The more I learn more new languages, the more I am surprised by just how
much C did things right.

I think we need explicit inout/out or we need to get rid of out, and use
pointers and the & operator. (Naturally, I don't want the former, so let me
sell you the former).

Flame away ...
Sep 19 2003
next sibling parent reply "Walter" <walter digitalmars.com> writes:
"Matthew Wilson" <matthew stlsoft.org> wrote in message
news:bkgkvd$2qv4$2 digitaldaemon.com...

 Well sorry to do this, chaps, but I think I'm coming to the conclusion


that


 within the calling code. It's just too ambiguous otherwise. I'm working


away

 on the reg stuff, and marking certain things out as appropriate, but then
 having to jump back and forth for the declarations.

 The more I learn more new languages, the more I am surprised by just how
 much C did things right.

 I think we need explicit inout/out or we need to get rid of out, and use
 pointers and the & operator. (Naturally, I don't want the former, so let


me

 sell you the former).

 Flame away ...


I don't understand. Can you post an example?
Sep 19 2003
next sibling parent "Matthew Wilson" <matthew stlsoft.org> writes:
What, and back up my preposterous claims!? You're joking right? <G>

Let me find one that exemplifies what I mean ...

"Walter" <walter digitalmars.com> wrote in message
news:bkglkj$2t77$1 digitaldaemon.com...

 "Matthew Wilson" <matthew stlsoft.org> wrote in message
 news:bkgkvd$2qv4$2 digitaldaemon.com...

 Well sorry to do this, chaps, but I think I'm coming to the conclusion


 that


 within the calling code. It's just too ambiguous otherwise. I'm working


 away

 on the reg stuff, and marking certain things out as appropriate, but




then

 having to jump back and forth for the declarations.

 The more I learn more new languages, the more I am surprised by just how
 much C did things right.

 I think we need explicit inout/out or we need to get rid of out, and use
 pointers and the & operator. (Naturally, I don't want the former, so let


 me

 sell you the former).

 Flame away ...


 I don't understand. Can you post an example?
Sep 19 2003
prev sibling parent reply "Matthew Wilson" <matthew stlsoft.org> writes:
Ok,

I've declared

    LONG RegQueryValueExA(in HKEY hkey, in LPCSTR lpValueName, in Reserved
reserved, out REG_VALUE_TYPE type, in void *lpData, inout DWORD cbData);

used as in

    private void Key_QueryValue(in HKEY hkey, in char[] name, out uint
value, out REG_VALUE_TYPE type)
    {
        //printf("Key_QueryValue(uint)\n");

        DWORD cbData = value.size;
        LONG res  = RegQueryValueExA(hkey, name, RESERVED, type, &value,
cbData);

        ...

cbData is inout, but it's impossible to tell that from looking at the
definition of Key_QueryValue(). Of course, I could not have been "smart" in
messing with the C signature of RegQueryValueExA(), but then I'd be using
the & within the client code. Which pretty much makes my case, I think.

This is one of the (few ;=) )things I don't like about C++, but at least
there's const to comfort us ... arf arf.

Ok, am OTT OT, so off now.




"Walter" <walter digitalmars.com> wrote in message
news:bkglkj$2t77$1 digitaldaemon.com...

 "Matthew Wilson" <matthew stlsoft.org> wrote in message
 news:bkgkvd$2qv4$2 digitaldaemon.com...

 Well sorry to do this, chaps, but I think I'm coming to the conclusion


 that


 within the calling code. It's just too ambiguous otherwise. I'm working


 away

 on the reg stuff, and marking certain things out as appropriate, but




then

 having to jump back and forth for the declarations.

 The more I learn more new languages, the more I am surprised by just how
 much C did things right.

 I think we need explicit inout/out or we need to get rid of out, and use
 pointers and the & operator. (Naturally, I don't want the former, so let


 me

 sell you the former).

 Flame away ...


 I don't understand. Can you post an example?
Sep 19 2003
next sibling parent "Matthew Wilson" <matthew stlsoft.org> writes:
btw, no-one need point out my omission of toStringz(). I'm fixing all those
atm.

"Matthew Wilson" <matthew stlsoft.org> wrote in message
news:bkgmi1$2v24$1 digitaldaemon.com...

 Ok,

 I've declared

     LONG RegQueryValueExA(in HKEY hkey, in LPCSTR lpValueName, in Reserved
 reserved, out REG_VALUE_TYPE type, in void *lpData, inout DWORD cbData);

 used as in

     private void Key_QueryValue(in HKEY hkey, in char[] name, out uint
 value, out REG_VALUE_TYPE type)
     {
         //printf("Key_QueryValue(uint)\n");

         DWORD cbData = value.size;
         LONG res  = RegQueryValueExA(hkey, name, RESERVED, type, &value,
 cbData);

         ...

 cbData is inout, but it's impossible to tell that from looking at the
 definition of Key_QueryValue(). Of course, I could not have been "smart"


in

 messing with the C signature of RegQueryValueExA(), but then I'd be using
 the & within the client code. Which pretty much makes my case, I think.

 This is one of the (few ;=) )things I don't like about C++, but at least
 there's const to comfort us ... arf arf.

 Ok, am OTT OT, so off now.




 "Walter" <walter digitalmars.com> wrote in message
 news:bkglkj$2t77$1 digitaldaemon.com...

 "Matthew Wilson" <matthew stlsoft.org> wrote in message
 news:bkgkvd$2qv4$2 digitaldaemon.com...

 Well sorry to do this, chaps, but I think I'm coming to the conclusion


 that








stated

 within the calling code. It's just too ambiguous otherwise. I'm






working

 away

 on the reg stuff, and marking certain things out as appropriate, but




 then

 having to jump back and forth for the declarations.

 The more I learn more new languages, the more I am surprised by just






how

 much C did things right.

 I think we need explicit inout/out or we need to get rid of out, and






use

 pointers and the & operator. (Naturally, I don't want the former, so






let

 me

 sell you the former).

 Flame away ...


 I don't understand. Can you post an example?
Sep 19 2003
prev sibling parent reply "Walter" <walter digitalmars.com> writes:
Oh, I see what you mean. You're interfacing with C code that uses a pointer
to simulate inout. The solution (as you suggested) is to NOT try to rewrite
the C declaration into using inout, just go ahead and use the pointer method
for it. Let's face it, when you're dealing with C code, you have to deal
with C'isms like pointers and addresses. Otherwise, you're faced with things
like trying to rewrite microsoft's enormous documentation database and all
the established wisdom of how to call those API functions. We've all got
better things to do <g>.

We had a similar discussion a while back about rewriting windows.d to use
strong typedefs rather than aliases. It's a noble thought, but I think it is
better for us to spend time writing cool new D class libraries than trying
to reengineer microsoft's APIs.
Sep 21 2003
parent reply Felix <Felix_member pathlink.com> writes:
As for inout parameters, calling

result=foo(x,&y);

(shouldn't) does not necessarily mean that &y is the pointer to y, simply it
means that y is an inout parameter. And this will be visible also at the calling
time, not only in the definition. Just an ideea.

Felix

In article <bkkrm2$v70$1 digitaldaemon.com>, Walter says...

Oh, I see what you mean. You're interfacing with C code that uses a pointer
to simulate inout. The solution (as you suggested) is to NOT try to rewrite
the C declaration into using inout, just go ahead and use the pointer method
for it. Let's face it, when you're dealing with C code, you have to deal
with C'isms like pointers and addresses. Otherwise, you're faced with things
like trying to rewrite microsoft's enormous documentation database and all
the established wisdom of how to call those API functions. We've all got
better things to do <g>.

We had a similar discussion a while back about rewriting windows.d to use
strong typedefs rather than aliases. It's a noble thought, but I think it is
better for us to spend time writing cool new D class libraries than trying
to reengineer microsoft's APIs.
Sep 21 2003
parent "Philippe Mori" <philippe_mori hotmail.com> writes:
 As for inout parameters, calling

 result=foo(x,&y);

 (shouldn't) does not necessarily mean that &y is the pointer to y, simply


it

 means that y is an inout parameter. And this will be visible also at the


calling

 time, not only in the definition. Just an ideea.

 Felix


In a language that does not even support const as a type modifier, this
would not make much sense to have that clue... I think that const modifier
is much more important... to makes safe program.

Also, I think it would be very easy to make an editor that would color
syntax in, inout and out parameters differently (for ex. in: italic, inout :
italic and bold, out: bold). Any any good editor should be able to
write you the prototype as you are written code.

I don't want to clutter my code with those & and if they are optional,¸
they would not always be used.

For me, using & is like hungarian notation... Although, it give us some
hints, we should not uses it. These were tricks for C language in the
80's that are less relevant these days...

Anyway, since & already has the meaning of an address, it should
be something else (maybe  ) but I think that by default, we should
not have to indicate it a calling site so I would opt for something
that indicate parameters we want to ensure they are not modified.

A modern language should be able to allows an editor to give the
programmer those hints while in program (and this will ensure that
those as consistent).

If we want to prevent an object to be modified, we should have a
way to make it const... We might have an operator or a predefined
property for that:

#a    // const access to a

a    // read-write access to a

or

a.const
a.readonly
a.readwrite
...

And if a const modifier is used, the final access would be strictiest
one (but we might have modifier that indicate that more access is
required so that it won't compile instead of restrictive the access)

a.needs_readwrite    // compile only if a is non-const (and not read-only)


And speaking of things that we might be able to control is the fact
that a reference can or cannot be null...
Sep 22 2003
prev sibling parent "Peter Hercek" <vvp no.post.spam.sk> writes:
"Matthew Wilson" <matthew stlsoft.org> wrote in message
news:bkgkvd$2qv4$2 digitaldaemon.com...
<snip>

 The more I learn more new languages, the more I am surprised by just how
 much C did things right.

 I think we need explicit inout/out or we need to get rid of out, and use
 pointers and the & operator. (Naturally, I don't want the former, so let me


:) You must be joking! Pointers and pointer arithmetic are root of all
 evil. They give also a lot of arguments against const/readonly <G>
... and const/readonly are only a wimpy way to make our imperative
 language to behave more predictably like functional languages do ;)
Sep 21 2003