PrimOps and Builtins

Data Structures
struct	PrimOp
	PrimOp function. More...

Typedefs
typedef void(*	PrimOpFun) (void *user_data, nix_c_context *context, EvalState *state, nix_value **args, nix_value *ret)
	Function pointer for primops.

Functions
PrimOp *	nix_alloc_primop (nix_c_context *context, PrimOpFun fun, int arity, const char *name, const char **args, const char *doc, void *user_data)
	Allocate a PrimOp.
nix_err	nix_register_primop (nix_c_context *context, PrimOp *primOp)
	add a primop to the builtins attribute set

Detailed Description

Typedef Documentation

PrimOpFun

typedef void(* PrimOpFun) (void *user_data, nix_c_context *context, EvalState *state, nix_value **args, nix_value *ret)

Function pointer for primops.

When you want to return an error, call nix_set_err_msg(context, NIX_ERR_UNKNOWN, "your error message here").

Parameters

[in]	user_data	Arbitrary data that was initially supplied to nix_alloc_primop
[out]	context	Stores error information.
[in]	state	Evaluator state
[in]	args	list of arguments. Note that these can be thunks and should be forced using nix_value_force before use.
[out]	ret	return value

See also

nix_alloc_primop, nix_init_primop

Function Documentation

nix_alloc_primop()

PrimOp * nix_alloc_primop	(	nix_c_context *	context,
		PrimOpFun	fun,
		int	arity,
		const char *	name,
		const char **	args,
		const char *	doc,
		void *	user_data )

Allocate a PrimOp.

Call nix_gc_decref() when you're done with the returned PrimOp.

Parameters

[out]	context	Optional, stores error information
[in]	fun	callback
[in]	arity	expected number of function arguments
[in]	name	function name
[in]	args	array of argument names, NULL-terminated
[in]	doc	optional, documentation for this primop
[in]	user_data	optional, arbitrary data, passed to the callback when it's called

Returns

primop, or null in case of errors

See also

nix_init_primop

nix_register_primop()

nix_err nix_register_primop	(	nix_c_context *	context,
		PrimOp *	primOp )

add a primop to the builtins attribute set

Only applies to States created after this call.

Moves your PrimOp content into the global evaluator registry, meaning your input PrimOp pointer becomes invalid. The PrimOp must not be used with nix_init_primop() before or after this call, as this would cause undefined behavior. You must call nix_gc_decref() on the original PrimOp pointer after this call to release your reference.

Parameters

[out]	context	Optional, stores error information
[in]	primOp	PrimOp to register

Returns

error code, NIX_OK on success