On Tuesday, 1 April 2025 at 09:21:25 UTC, Daniel Donnelly, Jr.
wrote:
Error: @safe function def.Def.toHash cannot call @system
function def.Def.toString: def.Def.toString is declared here...
```
I've always wondered about this, because I run into it every
time I have an idea and begin to code. It's a major bottleneck
to my coding performance.
How can we fix it?
The function (toHash) does not return any values. Maybe it's the
reason for the error, but let me share code for inspiration.
Maybe it's not simple, but I use this way:
```d
class C(T)
{
size_t id;
private T latex;
invariant {
static assert(!__traits(isFloating, T));
}
this() {
if (latex == latex.init) id = size_t.max;
else id = typeid(latex).getHash(&latex);
}
this(T value) {
latex = value;
this();
}
size_t length() => toString.length;//*
string opUnary(string op)() const
if (op == "*") {
import std.string : format;
return format("@%s", &latex);
}//*/
override const @safe nothrow
{
string toString()
{
import std.conv : to;
return latex.to!string;
}
size_t toHash()
{
static if (is(T == string))
{
auto i = toString;
return i.hashOf;
} else return id;
}
bool opEquals(Object rhs)
{
return rhs.toHash == this.toHash; /*
return rhs is this;//*/
}
}
}
unittest
{
auto cHelper(T)(T value) => new C!T(value);
auto a = cHelper("foo");
auto b = cHelper("zoo");
assert(a != b, "equalised!");
assert(*a != *b);
// but ->
assert(a.id == a.toHash); // or
assert(b.id == b.toHash);
imported!"std.stdio".writeln(*a);
// "@7F......"
}
SDB@79
