On Wednesday, 17 September 2025 at 22:16:50 UTC, Brother Bill
wrote:
In the following from Programming in D, page 483, we use
function keyword.
I expect that the first int in
```
int function(int);
```
represents the return value.
What does the second (int) refer to?
Then there is another example with 'delegate' instead of
'function.
```
import std.stdio;
void main()
{
}
alias Calculator = int function(int);
Calculator makeCalculator()
{
int increment = 10;
return value => increment + value; // ← compilation ERROR
}
```
To give a proper reply, `function` is the a function pointer
type, in D function pointers are strongly typed using this
keyword. `delegate` is a function pointer but with extra data
along with it, to eg. a class function would be a delegate due to
the hidden `this` pointer that tags along.
in this case `int function(int)` means "A function which takes an
integer argument, and returns an integer."
