On Tuesday, 11 July 2017 at 23:50:26 UTC, Steven Schveighoffer
wrote:
On 7/11/17 7:21 PM, H. S. Teoh via Digitalmars-d wrote:
On Tue, Jul 11, 2017 at 07:18:51PM -0400, Steven Schveighoffer
via Digitalmars-d wrote:
[...]
3. The only controversial part I see is that `break` doesn't
break
from the foreach loop. While I agree with the reasoning, and
support
that concept, the truth is we currently have a "poor man's"
static
foreach using a foreach over a tuple, and that DOES break
from the
loop.
This is a false impression. It actually does not break from
the loop,
but inserts a break in the generated code, and continues to
unroll the
rest of the loop. It's only at codegen that the subsequent
iterations
are detected as dead code and elided. See:
https://wiki.dlang.org/User:Quickfur/Compile-time_vs._compile-time#.22static.22_foreach_does_NOT_interpret_break_and_continue
Yes, I know that it still generates all the code, but the break
is still interpreted as breaking out of the loop. Timon's
proposal says it "does not interact with break", so I interpret
that as meaning it should break out of whatever construct is
surrounding the loop, not the loop itself.
Currently this:
foreach(j; 0 .. 2)
foreach(i; AliasSeq!(0, 1))
{
writeln(i);
static if(i == 0)
break;
}
will print
0
0
Whereas with my understanding, this:
foreach(j; 0 .. 2)
static foreach(i; 0 .. 2)
{
writeln(i);
static if(i == 0)
break;
}
would print
0
This seems too confusing.
-Steve
break inside a case inside a static foreach inside a switch is an
interesting case for this sort of reasoning
