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digitalmars.D.learn - What is the point of D_Version2

reply Derek Parnell <derek psych.ward> writes:
Okay, I just don't get it.

This code below doesn't compile in V1 dmd.

version(D_Version2)
{
    alias const(wchar)[] wstring;
    alias const(dchar)[] dstring;
}
else
{
    alias char[] string;
    alias wchar[] wstring;
    alias dchar[] dstring;
}


I can understand why - because the first two alias declarations have
invalid V1 syntax - but doesn't that make the whole D_Version2 thing
pointless?

-- 
Derek Parnell
Melbourne, Australia
skype: derek.j.parnell
Sep 02 2007
next sibling parent reply Derek Parnell <derek psych.ward> writes:
On Sun, 2 Sep 2007 22:50:32 +1000, Derek Parnell wrote:

P.S. I finally got Bud to compile using V2 after about a thousand tiny
changes and now I want to tweak so I can also compile the same source in
V1. 

Needless to say, but there will be a slight delay in the next Bud release
until I sort out this next bloody irritation.

-- 
Derek Parnell
Melbourne, Australia
skype: derek.j.parnell
Sep 02 2007
parent Bill Baxter <dnewsgroup billbaxter.com> writes:
Derek Parnell wrote:

 On Sun, 2 Sep 2007 22:50:32 +1000, Derek Parnell wrote:
 
 P.S. I finally got Bud to compile using V2 after about a thousand tiny
 changes and now I want to tweak so I can also compile the same source in
 V1. 
 
 Needless to say, but there will be a slight delay in the next Bud release
 until I sort out this next bloody irritation.
 



Can you work around it by separating the aliases out into separate v1 
and v2 d-files?  Like

version(D_Version2)
{
    import v2types;
}
else
{
    import v1types;
}

--bb
Sep 02 2007
prev sibling next sibling parent Witold Baryluk <baryluk smp.if.uj.edu.pl> writes:
Dnia Sun, 2 Sep 2007 22:50:32 +1000
Derek Parnell <derek psych.ward> napisa=B3/a:


 Okay, I just don't get it.
=20
 This code below doesn't compile in V1 dmd.
=20
 version(D_Version2)
 {
     alias const(wchar)[] wstring;
     alias const(dchar)[] dstring;
 }
 else
 {
     alias char[] string;
     alias wchar[] wstring;
     alias dchar[] dstring;
 }
=20
=20
 I can understand why - because the first two alias declarations have
 invalid V1 syntax - but doesn't that make the whole D_Version2 thing
 pointless?



Unfortunetly this is correct behavior.
Even when D_Version2 is undefined, anything which is inside must be
syntacticly correct. const(wchar) is incorrect for D1.

:/
--=20
Witold Baryluk, aleph0
MAIL: baryluk smp.if.uj.edu.pl
JID: movax jabber.autocom.pl
Sep 02 2007
prev sibling next sibling parent reply 0ffh <spam frankhirsch.net> writes:
Derek Parnell wrote:

 This code below doesn't compile in V1 dmd.
 [...]
 I can understand why - because the first two alias declarations have
 invalid V1 syntax - but doesn't that make the whole D_Version2 thing
 pointless?



Um, I see it's a pain. Surely you know the string mixin workaround?

Regards, Frank
Sep 02 2007
next sibling parent 0ffh <spam frankhirsch.net> writes:
0ffh wrote:

 Um, I see it's a pain. Surely you know the string mixin workaround?



Someone posted it somewhere at some time.
I currently use this for strings:

---<snip>---

version (D_Version2)
{
	mixin("alias invariant(char)* icptr;");
	alias char* cptr;
}
else
{
	alias char*  icptr;
	alias char*  cptr;
	alias char[] string;
}

---<snap>---

Or were you just complaining about the lack of elegance here?

Regards, Frank
Sep 02 2007
prev sibling parent Kirk McDonald <kirklin.mcdonald gmail.com> writes:
0ffh wrote:

 Derek Parnell wrote:
 

 This code below doesn't compile in V1 dmd.
 [...]
 I can understand why - because the first two alias declarations have
 invalid V1 syntax - but doesn't that make the whole D_Version2 thing
 pointless?



 
 Um, I see it's a pain. Surely you know the string mixin workaround?
 
 Regards, Frank
 
 



For the record, the string mixin workaround looks like this:

version (D_Version2) {
     mixin("alias const(char)* c_str;");
} else {
     alias char* c_str;
}

You can find this code near the top of the Python header.
http://dsource.org/projects/pyd/browser/trunk/infrastructure/python/python.d

So far as I can tell, I was the first person to come up with (or at 
least use) this workaround, but others may have come up with it on their 
own.

-- 
Kirk McDonald
http://kirkmcdonald.blogspot.com
Pyd: Connecting D and Python
http://pyd.dsource.org
Sep 02 2007
prev sibling parent torhu <no spam.invalid> writes:
Derek Parnell wrote:

 Okay, I just don't get it.
 
 This code below doesn't compile in V1 dmd.
 
 version(D_Version2)
 {
     alias const(wchar)[] wstring;
     alias const(dchar)[] dstring;
 }
 else
 {
     alias char[] string;
     alias wchar[] wstring;
     alias dchar[] dstring;
 }
 
 
 I can understand why - because the first two alias declarations have
 invalid V1 syntax - but doesn't that make the whole D_Version2 thing
 pointless?
 



Have you read this thread?  Thomas Kuehne explains how to write code 
that works in both D 1 and 2.

http://www.digitalmars.com/d/archives/digitalmars/D/supporting_DMD-1.016_and_DMD-2.000_with_the_same_source_code_54628.html
Sep 02 2007