On Thursday, 24 May 2018 at 08:16:30 UTC, biocyberman wrote:
Some C and C++ projects I am working on use pointers and
references extensively: to pass as function arguments, and to
return from a function. For function argument I would use
`ref`, but for return types, I can't use `ref` and can't return
a pointer. What should be the proper way to handle this? Do I
have to change function signature (i.e. return type) For
example, the following function:
```
//C++ version, from:
https://github.com/bioslaD/fastp/blob/orig/src/read.cpp#L69
Read* Read::reverseComplement(){
Sequence seq = ~mSeq;
string qual;
qual.assign(mQuality.rbegin(), mQuality.rend());
string strand = (mStrand=="+") ? "-" : "+";
return new Read(mName, seq, strand, qual);
}
// D version:
Read reverseComplement(){
Sequence seq = ~mSeq;
dchar[] qual = cast(dchar[])mQuality.dup;
reverse(qual);
string strand = (mStrand=="+") ? "-" : "+";
Read newRead = new Read(mName, seq, strand,
cast(string)qual);
// return &newRead does not work: returning `& newRead`
escapes a reference to local variable newRead
return newRead;
}
```
Let's not focus on the function body, I don't know how to
handle the return type in cases like this for the D version.
it looks like Read is a D class? in which case it already returns
by reference.
If you make Read a struct then all you need do is change the
function signature from
Read reverseComplement()
to
Read* reverseComplement()
about the function body
use mQuality.dup.representation.reverse;
dchar[] qual = cast(dchar[])mQuality.dup;
reverse(qual);
mQuality = cast(string)qual;
does not do what you want it to do.
