On Wednesday, 16 September 2020 at 18:34:05 UTC, Adam D. Ruppe
wrote:
On Wednesday, 16 September 2020 at 17:59:41 UTC, Remi wrote:
I tried to modify the hello.d example from your blog post. It
works without changes but when I tried to do a string
concatenation
Yeah, concatenation is one of the features that uses druntime,
and specifically, it is done through TypeInfo. I would actually
personally skip it if you are doing a minimal custom thing.
If you skip it, you can implement your own type instead of
using the built-in array concat. You can make a struct with an
operator overload to look basically the same, and it can give a
slice to pass to other functions. This is much easier here - no
druntime code needed and the user code will be clearer that
they might have to manage the memory. Typical code with normal
append tends to just assume there's no stomping, that the GC
takes care of it, etc.
I'm hitting linker errors related to TypeInfo:
But if you do implement it, as of right now, you have to define
TypeInfo. Which suckssssss because it is super tedious. There's
a WIP pull request up there with dmd to templatize this which
would help a lot. But right now it means implementing at least
some of it.
You'd need the base class TypeInfo, then TypeInfo_a (a ==
"char"), TypeInfo_Array, TypeInfo_Aa (which means "array of
char"), then finally, TypeInfo_Aya, which is "array of
immutable char", aka, string.
Once you get enough of that up - and the compiler is picky
about those right now - then the append operation is
`_d_arrayappendcTX`, which takes TypeInfo as a param.
Search these names in the druntime source to see their official
implementations... it is a bit of a beast, which is why I
recommend actually skipping them if you can. It quickly
explodes in size and by the time you follow it to its final
conclusion, you've reimplemented 3/4 of full druntime anyway
and might as well have just done a port.
I don't mind implementing enough to get my project running, I
first tried Sebastiaan's WASM druntime port but I realised the
project I'm working on wouldn't need that much to get running so
I thought maybe I can slowly port each part until I get the
project to run.
My problem here is mostly understanding the __initZ symbol and
where it comes from. I mostly want classes and the bare minimum
of std like you did for Tetris in WebAssembly for example. My
project is OpenGL/SDL2 so there's a lot of glue code but just
ruinning a simple example gives me problems I want to understand
first.
I'll probably try what you describe in your "Zero-runtime
classes" actually, and hopefully I can get away without the
string manipulation or replace it with my own version of it.
