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HTTPServerRequest.context.get cannot be used with classes and interfaces #2004

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quickfur opened this Issue Dec 14, 2017 · 0 comments

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quickfur commented Dec 14, 2017

Code:

interface MyInterface { }
void func(HTTPServerRequest req) {
    auto intf = req.context.get!MyInterface("abc");
}

Compiler output:

/usr/src/d/vibe.d/utils/vibe/utils/dictionarylist.d(198): Error: cannot implicitly convert expression `this.get(key, delegate const(MyInterface)() => null)` of type `const(MyInterface)` to `inout(MyInterface)`
main.d(41): Error: template instance vibe.utils.dictionarylist.DictionaryList!(VariantN!32LU, true, 2LU, false).DictionaryList.get!(MyInterface) error instantiating

The same error occurs if the interface is changed to class, and if the class/interface isn't directly stored in req.context, but is part of a struct.

Expected behaviour: it should be possible to store class and interface references in HTTPServerRequest.context.

Currently-known workaround: specify the default argument with T.init explicltly.

interface MyInterface { }
void func(HTTPServerRequest req) {
    auto intf = req.context.get!MyInterface("abc",
        MyInterface.init); // <-- this works
}

I looked at the code and found comments mentioning a dmd bug and a bunch of overloads that supposedly works around said bug. However, the workaround doesn't seem to work for classes/interfaces.

@quickfur quickfur changed the title HTTPServerRequest.context.get cannot be instantiated with classes and interfaces HTTPServerRequest.context.get cannot be used with classes and interfaces Dec 14, 2017

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