Re: More than one invariant per struct/class

[Alex Rønne Petersen]

On 04-08-2011 11:32, simendsjo wrote:

I would like to use a template mixin to add some fields to a struct, but
I'd also like the template to add additional invariant checks without
having to remember to add this for all struct/classes that mixes in this
code.

class C {
int a;
}

mixin template EmbedC() {
C _c;

// oops.. more than one invariant
invariant() {
assert(_c);
}

void close() {
_c = null;
}
}

struct S {
int i = 10;
invariant() {
assert(i >= 10);
}

mixin EmbedC!();
}

void main() {
S s;
s.close();
s._c.a = 10; // access violation, but I want assertion from invariant
}

This sounds reasonable and useful to me.

- Alex