Hello,

I had converted the following C code fragment:

#ifndef MYTYPE
#define MYTYPE
typedef int mytype;
#endif

into the following D code
fragment:

version (MYTYPE) {
} else {
	version = MYTYPE;
	alias int
mytype;
}

which used to work until I moved from DMD version 0.121 to 0.127.
Now it
reports an error of the form:

mytype.d:3: version MYTYPE defined
after use

The changelog of DMD version 0.127 states that forward references
of version
and debug identifiers aren't allowed anymore. It doesn't cite a
reason and
searching for one didn't yield anything.

I thought I may use the
"iftype" construct but the compiler says it is
deprecated in favour of "static
if", but "static if" isn't allowed at
global/module scope.

I have two
questions:

1. Does anybody know of a reason for the restriction on forward
references of
version and debug identifiers? If yes, can you please point me to
any relevant
discussion.

2. Can anybody please help me with my problem of
identifying a pre-exisiting
type and defining it if it doesn't exist? I'd
appreciate a simple example.

Hopefully,
Jay

"Jay" <Jay_member@pathlink.com> wrote in message news:dacjds$2037$1@digitaldaemon.com...
> I thought I may use the
> "iftype" construct but the compiler says it is
> deprecated in favour of "static
> if", but "static if" isn't allowed at
> global/module scope.

iftype() has been replaced with the "is" expression.  You can check if a type has been defined by just placing the type as the parameter to "is":

if(is(mytype))
{
    ...
}

Since is() is evaluated at compile time, it can be used in static if() statements.  However, the problem, as you said, is that static if() is not allowed at global scope.  Perhaps this limitation could be removed, as static if() is more like a conditional compilation expression than anything else, and could be allowed at global scope.

> 1. Does anybody know of a reason for the restriction on forward
> references of
> version and debug identifiers?

I believe it was because version statements in imported modules were affecting compilation, as well as files which changed versions in the middle of the file didn't work correctly, as the version was being applied to all code.  So now it works kind of like a public: label - it only affects code that follows.