On Monday, 28 August 2023 at 10:20:14 UTC, Basile B. wrote:
On Monday, 28 August 2023 at 06:38:50 UTC, Vino wrote:
Hi All,
The the below code is not working, hence requesting your
help.
Code:
```
import std.stdio;
import std.process: environment;
void main () {
int* ext(string) = &environment.get("PATHEXT");
writeln(*ext);
}
```
Problems is that "PATHEXT" is a runtime argument. If you really
want to get a pointer to the function for that runtime argument
you can use a lambda:
```d
import std.stdio;
import std.process: environment;
void main () {
alias atGet = {return environment.get("PATHEXT");}; //
really lazy
writeln(atGet); // pointer to the lambda
writeln((*atGet)()); // call the lambda
}
```
There might be other ways, but less idiomatic (using a struct +
opCall, a.k.a a "functor")
To go further, the correct code for syntax you wanted to use is
actually
```d
alias Ext_T = string (const char[] a, string b); // define a
function type
alias Ext_PT = Ext_T*; // define a function **pointer** type
Ext_PT ext = &environment.get;
```
But as you can see that does not allow to capture the argument.
Also it only work as AliasDeclaration RHS.
