How to get to a class initializer through introspection?
SeeWebsiteForEmail at erdani.org
Tue Aug 4 02:03:34 UTC 2020
On 8/3/20 10:44 AM, Johan wrote:
> On Monday, 3 August 2020 at 13:01:55 UTC, Andrei Alexandrescu wrote:
>> Would it be effective to iterate through the .tupleof and initialize
>> each in turn?
> Possibly. IIRC, the spec obliges us to initialize the padding in-between
> address-aligned members aswell, such that a memcmp works to compare
> structs. If that is true, then we have to initialize the padding aswell
> and a memcpy would be that much nicer.
To play devil's advocate, the padding bytes should not have been changed
by user code in the first place :o).
> If `__traits(type, getInitializer)` would return a symbol, then memcpy
> is easy and we're done. However, that forces us to emit these init
> symbols, except for very simple cases like all-zeros initialization (for
> which LDC does no longer emit an init symbol). It is very benificial for
> binary size to elide these all-zero initializer symbols. I don't know
> how much benefit there is for eliding near-zero symbols.
> If `__traits(type, getInitializer)` would return a function, then that's
> a different story...
> My current solution [*]:
> [*] Hits an obscure mangling bug, so doesn't quite work with Weka's
> codebase yet
Cool. Also the https://dlang.org/spec/traits.html#isZeroInit flag may help.
There's also the related trickery TypeInfo uses for the initializer()
Array with null pointer and non-zero length.
There's also offset info for fields available so I'd say there is enough
material for a complete solution.
Just throwing everything at the wall...
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