Translate C/C++ patern: return a pointer

biocyberman biocyberman at gmail.com
Thu May 24 08:16:30 UTC 2018


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.



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