On Sunday, 24 March 2019 at 18:18:39 UTC, sighoya wrote:
Hmm..., sounds like bad news. Is there any mixin technology for
statements?
mixin() works for statements too.
It is the *context* though. If mixin() appears where the compiler
expects an expression, it must give an expression. Ditto for
statements (and for declarations btw). Consider
int main() {
// compiler expecting a statement here, so
mixin("if(true) {}"); // allowed
// but here it is expecting an expression
return mixin("some_expression");
}
This is also the reason why mixin sometimes requires ; and
sometimes requires a LACK of ;
int main() {
int a;
mixin("a = 10;"); // the ; inside the mixin is required there
return mixin("a"); // but mixin("a;"); there would be an error
}
Think of mixin() not as pasting code per se, but pasting an AST
node inside the compiler's data structures. It must be a complete
node of that tree that can be substituted in.
