www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.learn - "foo.bar !in baz" not allowed?

reply Magnus Lie Hetland <magnus hetland.org> writes:
For some reason, it seems like expressions of the form "foo.bar !in 
baz" aren't allowed. I suspect this is a grammar/parser problem -- the 
bang is interpreted as a template argument operator, rather than a 
negation operator, and there's really no need to make that 
interpretation when it is immediately followed by "in". This suspicion 
is strengthened by the fact that "bar !in baz" is fine, as is 
"(foo.bar) !in baz".

Should I file this as a bug?

Small sample program:

struct Foo {
    uint bar;
}

struct Baz {
    bool opIn_r(uint e) {
        return false;
    }
}

void main() {
    Baz baz;
    Foo foo;
    auto res = (foo.bar) !in baz;
    res = !(foo.bar in baz);
    // res = foo.bar !in baz; // Not OK...
    uint frozz;
    res = frozz !in baz;
}

-- 
Magnus Lie Hetland
http://hetland.org
Mar 13 2011
parent reply spir <denis.spir gmail.com> writes:
On 03/13/2011 07:58 PM, Magnus Lie Hetland wrote:
 For some reason, it seems like expressions of the form "foo.bar !in baz" aren't
 allowed. I suspect this is a grammar/parser problem -- the bang is interpreted
 as a template argument operator, rather than a negation operator, and there's
 really no need to make that interpretation when it is immediately followed by
 "in". This suspicion is strengthened by the fact that "bar !in baz" is fine, as
 is "(foo.bar) !in baz".

 Should I file this as a bug?

 Small sample program:

 struct Foo {
 uint bar;
 }

 struct Baz {
 bool opIn_r(uint e) {
 return false;
 }
 }

 void main() {
 Baz baz;
 Foo foo;
 auto res = (foo.bar) !in baz;
 res = !(foo.bar in baz);
 // res = foo.bar !in baz; // Not OK...
 uint frozz;
 res = frozz !in baz;
 }

Would be nice to copy the error, wouldn't it? template argument expected following ! Anyway, this is definitely a bug in my opinion. Denis -- _________________ vita es estrany spir.wikidot.com
Mar 13 2011
parent Magnus Lie Hetland <magnus hetland.org> writes:
On 2011-03-13 21:27:27 +0100, spir said:

 On 03/13/2011 07:58 PM, Magnus Lie Hetland wrote:
 For some reason, it seems like expressions of the form "foo.bar !in baz" aren't
 allowed. I suspect this is a grammar/parser problem -- the bang is interpreted
 as a template argument operator, rather than a negation operator,


 Would be nice to copy the error, wouldn't it?
 	template argument expected following !

Ah. I thought my explanation (see above) made that clear.
 Anyway, this is definitely a bug in my opinion.

Turns out it's an old one. Sorry about that: http://d.puremagic.com/issues/show_bug.cgi?id=4159 -- Magnus Lie Hetland http://hetland.org
Mar 13 2011