Re: Convert mixin to function call
It should be obvious that these are simplifications. I can't pass the variables directly as parameters as in the real case the names may only be partially specified.
Re: Convert mixin to function call
https://dpaste.dzfl.pl/fb49bf834cff
import std.stdio;
auto Q(string A)()
{
auto foo()
{
auto d = mixin(Z!(A)());
return d;
}
return foo()();
}
auto X(string A, string N)()
{
return N~" = (() { int y = 4; return "~A~" + y + 5; })();";
}
auto Z(string A)()
{
return "() { int y = 4; return "~A~" + y + 5; }";
}
void main()
{
int x = 3;
double y = 0;
pragma(msg, (X!("x", "y")()));
mixin(X!("x", "y")());
y = Q!("x")();
writeln(y);
}
using Q is more ideomatic but foo does not have access to x which
is required(since Q should behave like a string mixin as far as
scope is concerned).
Re: Convert mixin to function call
Also, one thing that would help would be able to create identifier names that are unique to avoid collisions. Does D have any ability to do such a thing?
Convert mixin to function call
I have a string mixin that returns a value or function that uses
the mixed in scope.
Currently I have to wrap the mixin in a delegate or local
function as to be able to get the value:
int x = 3;
int y = 1;
auto foo() { mixin(X!("x")); }
This allows the the mixin to see the scope but keep the mixin
variables local so they do not shadow anything unintentionally.
auto X(string A)()
{
return "int y = 4; return "~A~" + y + 5;";
}
foo will just return 8 but I cannot simply mixin within the main
scope or the scope will return unintentionally.
int x = 3;
mixin(X!("x")) // <- hidden return
Using foo works fine but adds a level of indirection I feel is
unnecessary. The only thing I feel can work is to rewrite X so
that it uses variables with random names to reduce shadowing
issues and to allow X to take a variable name to put the result
in:
auto X(string A, string N)()
{
return "{ int _342sdfs = 4; "~N~" = "~A~" + _342sdfs + 5;}";
}
which complicates things significantly. My hope is that D would
inline the function call.
Ideally I'd like to be able to sort of use the mixin as a
function and simply call it:
val = mixin(X!("x"))();
which I could do by internally using a delegate inside the mixin
auto X(string A)()
{
return "(() { int y = 4; return "~A~" + y + 5; })";
}
except that the mixin syntax does not allow one to use it in an
expression.
Remember that the mixin must be able to see the scope it is mixed
in at so one can't wrap this in a template use it as far as I
know?
Although, one can do
mixin(X!("val", "x"));
which does the ugly work.
It would be nice to be able to get this process to look as much
like normal D code as possible.
the idea is to try to write "local" string mixins that are messy
and not "C'ish" looking in to "C'ish" looking code.
