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- Subject: Re: How close to C do you make your binding?
- From: Philipp Janda <siffiejoe@...>
- Date: Wed, 18 Jun 2014 19:33:42 +0200
Am 18.06.2014 16:37 schröbte Andrew Starks:
We have our nanomsg binding that we recently remade. It was very C heavy
and now it's the opposite. We're making an "nml.core" that looks *pretty
much* exactly like the C API. The higher level binding wraps it in a
If you have made bindings this way, how far do you take the idea of
sticking to the C API in your core layer?
Do you strive for perfect adherence to the original C documentation? Do you
change things like "-1" or "0" to "false", where appropriate? Do you use
multiple returns where their API is using pointers?
I consider a C binding to be low-level if there is a one-to-one
function/type mapping between the Lua API and the C API. I usually adapt
* use multiple return values (Lua doesn't have output parameters)
* make some parameters optional and provide default values
* if there is a single array parameter, I often support both a table
and a vararg list in the Lua API
* error handling (==> nil, error message, [extra info])
* enums get replaced by strings or userdata
* functions are renamed (usually to remove a redundant prefix)
* some functions are additionally made available as methods
* some functions don't get bound at all (e.g. if they can cause crashes)
* some functions are called automatically (initializers, finalizers,
cleanup functions (=> also to avoid crashes))
You can still reuse C tutorials, because the sequence of the API
functions and the mental model are the same. The usual LDoc-like API
documentation should be enough to handle the differences.
One thing I'm not sure about yet is whether to expose simple data
structs/unions as userdata or as tables. So far I've used userdata ...