On 2010-11-11 15:05:08 -0500, Rainer Deyke <rain...@eldwood.com> said:
On 11/11/2010 06:06, Michel Fortin wrote:
On 2010-11-10 23:51:38 -0500, Rainer Deyke <rain...@eldwood.com> said:
As it turns out, the joining of adjacent strings is a critical feature.
Consider the following:
f("a" "b");
f("a" ~ "b");
These are /not/ equivalent. In the former cases, 'f' receives a string
literal as argument, which means that the string is guaranteed to be
zero terminated. In the latter case, 'f' receives an expression (which
can be evaluated at compile time) as argument, so the string may not be
zero terminated. This is a critical difference if 'f' is a (wrapper
around a) C function.
You worry too much. With 'f' a wrapper around a C function that takes a
const(char)* argument, if the argument is not a literal string then it
won't compile. Only string literals are implicitly convertible to
const(char)*, not 'string' variables.
You just restated the problem. There needs to be a way to break up
string literals while still treating them as a single string literal
that is convertible to 'const(char)*'. You could overload binary '~'
for this, but I think this may be confusing.
Perhaps I misstated things a bit. Only *compile-time* strings are
implicitly convertible to const(char)*. The expression "abc"~"def" is a
string known at compile-time, and is written in the object file as one
string literal.
Note that compile-time strings could also come from enums and
templates. This will be written as one string literal in the object
file:
enum hello = "hello";
template T(alias s) { enum T = s; }
unittest {
f(hello ~ T!"world");
}
This call to 'f' works because hello~T!"world" forms a compile-time
string and is implicitly convertible to a const(char)*. Try it! Also
try changing 'enum' with 'auto' to make hello a variable and it'll no
longer work.
--
Michel Fortin
michel.for...@michelf.com
http://michelf.com/
