bytedeco/javacpp

Creating instances of C++ templates with parameter packs

Open

#773 opened on Jul 21, 2024

View on GitHub
 (3 comments) (0 reactions) (0 assignees)Java (620 forks)batch import
enhancementhelp wanted

Repository metrics

Stars
 (4,279 stars)
PR merge metrics
 (No merged PRs in 30d)

Description

I tried to make a struct with a parameter pack template type as such:

template<typename... Args>
struct Foo
{
    virtual void bar(Args... args) {}
};

and I made a function that takes a specialization of this struct:

void fooFunc(Foo<int, double> b) {...}

I put it in an InfoMapper:

infoMap.put(new Info("Foo<int,double>").pointerTypes("TestType").virtualize());

and it did generate a function that takes the correct type

public native void pPackTest(@ByVal TestType b);

But failed to generate the actual .java file (TestType.java) Is there something I can do about this, or is this just a limitation of the parser?

Contributor guide

Research direction
Investigate the JavaCPP code generation logic for C++ parameter pack templates. Trace how the parser handles variadic templates and why it fails to generate the .java file for the specialization.
Tech stack
java
Domain
backendapi
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
C++Java
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60