On Tuesday, 5 December 2023 at 00:31:35 UTC, H. S. Teoh wrote:
On Mon, Dec 04, 2023 at 11:46:45PM +0000, DLearner via
Digitalmars-d-learn wrote: [...]
Basically, B corresponds to the whole record (and only a whole
record
can be read).
But the task only requires Var1 and Var2, the last two fields
on the record.
By putting all the irrelevant fields into A, and defining B as
above,
program remains unpolluted with data it does not need.
[...]
Sounds like what you need is something like this:
struct Record {
struct UnimportantStuff {
...
}
UnimportantStuff unimportant;
struct ImportantStuff {
...
}
ImportantStuff important;
}
ImportantStuff readData() {
Record rec = readData(...); // read entire record
return rec.important; // discard unimportant stuff
}
int main() {
...
ImportantStuff data = readData(); // only important stuff
returned
processData(data);
...
}
T
I think that what you propose would work.
However, what I was really interested in was finding a way (using
your example) of not instantiating UnimportantStuff anywhere.
Your suggestion instantiates it at:
```
UnimportantStuff unimportant;
```
I was thinking (again using your example) of something like:
```
struct UnimportantStuff {
...
}
struct Record {
UnimportantStuff.sizeof;
struct ImportantStuff {
...
}
ImportantStuff important;
}
```
But was concerned about possible alignment issues.
