Re: Why isn't == used to compare structs
Trass3r wrote: Why isn't == used to compare the struct members in the code above? I mean, if I compare the structs with == it could also use == to compare the members. If I use is to compare the structs it could use is to compare them members. Structs are compared *bitwise*! Not in D2, any more. If a member has an opEquals, it's compared using ==.
Re: Why isn't == used to compare structs
Don wrote: Trass3r wrote: Why isn't == used to compare the struct members in the code above? I mean, if I compare the structs with == it could also use == to compare the members. If I use is to compare the structs it could use is to compare them members. Structs are compared *bitwise*! Not in D2, any more. If a member has an opEquals, it's compared using ==. Seems arrays inside structs still are not compared with ==.
Re: Why isn't == used to compare structs
Structs are compared *bitwise*! Not in D2, any more. If a member has an opEquals, it's compared using ==. Ok, what's the rationale?
Re: Why isn't == used to compare structs
On Tue, 09 Feb 2010 14:58:13 -0500, grauzone n...@example.net wrote: Don wrote: Trass3r wrote: Why isn't == used to compare the struct members in the code above? I mean, if I compare the structs with == it could also use == to compare the members. If I use is to compare the structs it could use is to compare them members. Structs are compared *bitwise*! Not in D2, any more. If a member has an opEquals, it's compared using ==. Seems arrays inside structs still are not compared with ==. http://d.puremagic.com/issues/show_bug.cgi?id=3789
Re: Why isn't == used to compare structs
Trass3r wrote: Structs are compared *bitwise*! Not in D2, any more. If a member has an opEquals, it's compared using ==. Ok, what's the rationale? If there is an opEquals, it should not be ignored. If it has no opEquals, it's just considered to be a bag of bits.
Why isn't == used to compare structs
struct String
{
char[] data;
}
void main ()
{
auto foo = String(foo);
auto bar = String(foo.dup);
assert(bar == foo);
}
Why isn't == used to compare the struct members in the code above? I
mean, if I compare the structs with == it could also use == to compare
the members. If I use is to compare the structs it could use is to
compare them members.
Re: Why isn't == used to compare structs
Am Mon, 08 Feb 2010 12:19:12 +0100
schrieb Jacob Carlborg d...@me.com:
struct String
{
char[] data;
}
void main ()
{
auto foo = String(foo);
auto bar = String(foo.dup);
assert(bar == foo);
}
Why isn't == used to compare the struct members in the code above? I
mean, if I compare the structs with == it could also use == to
compare the members. If I use is to compare the structs it could
use is to compare them members.
How should == be used for this struct?
struct Foo
{
union
{
char[] dataA;
long dataB;
}
}
Foo a,b;
a.dataA = abc;
b.dataA = abc.dup;
Now a.dataA == b.dataA, but a.dataB != b.dataB.
Re: Why isn't == used to compare structs
Why isn't == used to compare the struct members in the code above? I mean, if I compare the structs with == it could also use == to compare the members. If I use is to compare the structs it could use is to compare them members. Structs are compared *bitwise*! When you dup your pointer is different and thus the structs are different.
Re: Why isn't == used to compare structs
On 02/08/2010 01:48 PM, Trass3r wrote: Why isn't == used to compare the struct members in the code above? I mean, if I compare the structs with == it could also use == to compare the members. If I use is to compare the structs it could use is to compare them members. Structs are compared *bitwise*! When you dup your pointer is different and thus the structs are different. I believe the question was *why* things are this way. I think it's weird.
Re: Why isn't == used to compare structs
I believe the question was *why* things are this way. I think it's weird. It's common behavior. In the end structs are just a way to map a memory range to some variable tuple. If you really need == for all members you can always overload opEquals!!
Re: Why isn't == used to compare structs
On 2/8/10 14:58, Pelle Månsson wrote: On 02/08/2010 01:48 PM, Trass3r wrote: Why isn't == used to compare the struct members in the code above? I mean, if I compare the structs with == it could also use == to compare the members. If I use is to compare the structs it could use is to compare them members. Structs are compared *bitwise*! When you dup your pointer is different and thus the structs are different. I believe the question was *why* things are this way. I think it's weird. Yes that was the question.
Re: Why isn't == used to compare structs
On 2/8/10 13:48, Trass3r wrote: Why isn't == used to compare the struct members in the code above? I mean, if I compare the structs with == it could also use == to compare the members. If I use is to compare the structs it could use is to compare them members. Structs are compared *bitwise*! When you dup your pointer is different and thus the structs are different. Yes, I intentionally duped the string to make sure they're not using the same memory. I was thinking of something like a transitive ==.
Re: Why isn't == used to compare structs
Yes, I intentionally duped the string to make sure they're not using the same memory. I was thinking of something like a transitive ==. Overload opEquals.
