Hi Edward,
thank you.
That knowledge revealed that the "Ozi" part was actually the version number.
So the "actual" package name seems to be
"Plugin-0.0.0.0-2QaFQQzYhnKJSPRXA7VtPe".
That leaves the random(?) characters behind the version number to be
explained.
But at least now I can exploit the fact that a
"libHSPlugin-0.0.0.0-2QaFQQzYhnKJSPRXA7VtPe.a" file is generated. So if
I don't find the complete answer I still have a more portable way for
discovery than inspecting headers.
That's quite useful.
Cheers,
MarLinn
On 2017-10-14 18:01, Edward Z. Yang wrote:
Hi MarLinn,
The mangling name is "z-encoded". It is documented here:
https://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler/SymbolNames
Edward
Excerpts from MarLinn's message of 2017-10-14 17:35:28 +0200:
Hi.
I'm experimenting with plug-ins right now. I did manage to dynamically
load functions at runtime. The caveat: Something (cabal? ghc?) mangles
the package names. For example, to load a function called "theFunction"
from a module called "Callee" in a package "Plugin", I had to address it
via the name
"Pluginzm0zi0zi0zi0zm2QaFQQzzYhnKJSPRXA7VtPe_Callee_theFunction_closure".
O…K. Most parts of that are clear, and thanks for making my package
cooler by appending a "z", but who is this Ozi guy and why is he rapping
about modems? Without knowing Ozi, the only way I found to get at this
magic string is to manually look at the actual ELF-header of the
compiled module. While that might be a robust way, it seems neither
portable nor elegant.
The "plugins" library failed too, probably for the same reason. (Or it's
under-documented. Probably both.) The "dynamic-loader" library does
something via c, therefore no.
Which brings me to the question: Is there any way for a module to get at
its own internal package name? Or even at the internal name of an
external package? If not, can I somehow recreate the magic mangling at
runtime? At first I thought the functions in the "Module", "Name" etc
modules of GHC might help – but it seems I either need an existing Name
(that I have no idea how to get) or I have to create one (with no idea
what magic mangler to call).
I'm asking this question here rather than on café as I feel that if
there is a solution, it's probably buried in the details of GHC.
Thanks for any suggestions,
MarLinn
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