Undefined symbol for, apparently, valid code?

[Arafel via Digitalmars-d-learn]

Well, it happened to me once [1], and the reason is that templated 
functions are final by default (since, as you said, it doesn't make 
sense for them to be anything else).

This way the body of the function is assumed to be in a different 
compilation unit (which is not, hence the linker error). If the variable 
had been declared of type "Foo" instead of "Asd" it would probably had 
worked, although this kind of defeat the purpose.

Whether it makes sense that this construction is allowed, is a different 
question. I personally it makes sense to have the user explicitly ask 
for "final", since we have otherwise "virtual by default", so this 
behaviour is completely unexpected be most users. The whole thing makes 
even less sense if you take into account that a explicit request to 
override is just silently ignored.

Finally, have also in mind that if the function had been declared 
abstract (as it arguably should), a compile-time error would have been 
generated [2].

[1]: http://forum.dlang.org/post/kgxwfsvznwzlnhrdplkc@forum.dlang.org
[2]: https://dpaste.dzfl.pl/22f7e0840f01




On 07/06/2017 08:48 AM, rikki cattermole wrote:
 >
 > Templates+classes = require function body.
 >
 > Why? Templated methods are not virtual, they are final and cannot be
 > inherited (so its a little strange that the override is valid).