On Sunday, 26 October 2014 at 10:48:46 UTC, ketmar via
Digitalmars-d-learn wrote:
Hello.
the following code is not working:
template prstr(string s) {
enum prstr = "write("~s.stringof~");\n";
}
string buildWriter() (string fmt) {
return prstr!(fmt[0..$-1]);
}
Your passing the runtime parameter `fmt` as template argument.
Try this:
string buildWriter(string fmt)() {
return prstr!(fmt[0..$-1]);
}
string writer(string fmt) () {
enum s = buildWriter(fmt);
and this:
enum s = buildWriter!(fmt);
return s;
}
void main () {
import std.stdio;
writeln(writer!"str"());
}
z40.d(6): Error: variable fmt cannot be read at compile time
z40.d(10): Error: template instance z40.buildWriter!() error
instantiating
z40.d(16): instantiated from here: writer!"str"
but why? fmt is known in CTFE and compiler can use it as string
literal
for instantiating `prstr`.
please, don't mind the idiocity of the code: this is just a
sample to
show what confuses me. i know about possibility of moving `fmt`
to
template argument, but i need it as function argument, 'cause
`buildWriter()` actually does string processing and i want to
instantiate `prstr` with the part of the string. and this
processing
cannot be done in 'foreach'.
and writing everything in functional style sux: it leads to
explosive
growing of the number of arguments passed to templates.
