On Saturday, 10 September 2022 at 22:13:01 UTC, frame wrote:
On Saturday, 10 September 2022 at 00:24:11 UTC, jwatson-CO-edu
wrote:
Hello,
I'm trying to create a dictionary of templated function
pointers. The functions should return `bool` and take a
differently-typed dynamics arrays `T[]` as an argument.
This won't work as you might expect. Your container would need
to support multiple types and may need overloads of operators
to become that magic.
But lets begin with a simple type. Consider your example fixed:
```d
alias FuncDict(T) = bool function(T[])[string]; // alias needs
T as parameter too...
FuncDict!(string) lookup; // ...so we can instantiate a
FuncDict with T = string
void main()
{
lookup["foo"] = function bool(string[] args) { return true;
};
}
```
As you can see `T` is bound to `string` here and cannot be
something else.
Ah, this gives me more information on how to use `alias`es,
thank you!
I can see that I have wished for a magical thing. So, my
solution will be to construct a catch-all struct `Payload` and
have that be my argument type from which various functions can
draw the data of their choice.
```d
struct Payload{
double[] dbbls;
string[] strns;
// Probably others ...
}
```
Application is a Dlang implementation of Little Scheme, from
the book "The Little Schemer". For it, I need a menu of
"primitive" base functions that form the foundation of anything
you might ask the interpreter to do. (Hence my wish for a
multi-type dict.)
Thanks again!
