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Subject: Re: Metaprogramming
From: Ville Voutilainen (ville.voutilainen_at_[hidden])
Date: 2020-10-24 12:35:41


On Sat, 24 Oct 2020 at 20:01, David Rector <davrec_at_[hidden]> wrote:
>
>
>
> On Oct 24, 2020, at 12:34 PM, Ville Voutilainen <ville.voutilainen_at_[hidden]> wrote:
>
> On Sat, 24 Oct 2020 at 19:17, David Rector via SG7 <sg7_at_[hidden]> wrote:
>
> # 3
> I think only strings should be injectible. Get rid of fragments -- they are a source of needless complexity. IIUC, Andrew proposes the ability to inject arbitary code strings via `|# ... #|` syntax. E.g. `consteval { |# "private: int i = 42;" #| }` would inject a private `i` into the enclosing class context (and result in a parse error if not in a class).
>
>
> That doesn't seem to be correct. The paper says that a |# ... #| is an
> identifier splice, not an arbitrary string.
>
> I am under the impression that building injected code with just
> strings or with just tokens is rather horrible
> for implementations? For syntax validation and semantic analysis, most
> likely. Token-soup-injection
> as a possibility sure made our clang friends balk in Toronto.
>
>
> What's so horrible about the implementation? Here's an old clang implementation, scroll down to the "metaparsing" part for examples:
>
> https://github.com/drec357/clang-meta

Perhaps Mr. Smith could illuminate us.


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