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C API: nix_get_string now accepts a callback to return the value

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José Luis Lafuente 2024-04-15 21:05:52 +02:00
parent 74e4bc9b1d
commit c75b143b6c
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6 changed files with 65 additions and 35 deletions
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37
doc/external-api/README.md
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@ -40,24 +40,37 @@ Nix expression `builtins.nixVersion`.
#include <nix_api_expr.h>
#include <nix_api_value.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// NOTE: This example lacks all error handling. Production code must check for
// errors, as some return values will be undefined.
int main() {
nix_libexpr_init(NULL);
Store* store = nix_store_open(NULL, "dummy://", NULL);
EvalState* state = nix_state_create(NULL, NULL, store); // empty search path (NIX_PATH)
Value *value = nix_alloc_value(NULL, state);
void my_get_string_cb(const char * start, unsigned int n, char ** user_data)
{
*user_data = strdup(start);
}
nix_expr_eval_from_string(NULL, state, "builtins.nixVersion", ".", value);
nix_value_force(NULL, state, value);
printf("Nix version: %s\n", nix_get_string(NULL, value));
int main()
{
nix_libexpr_init(NULL);
nix_gc_decref(NULL, value);
nix_state_free(state);
nix_store_free(store);
return 0;
Store * store = nix_store_open(NULL, "dummy://", NULL);
EvalState * state = nix_state_create(NULL, NULL, store); // empty search path (NIX_PATH)
Value * value = nix_alloc_value(NULL, state);
nix_expr_eval_from_string(NULL, state, "builtins.nixVersion", ".", value);
nix_value_force(NULL, state, value);
char * version;
nix_get_string(NULL, value, my_get_string_cb, version);
printf("Nix version: %s\n", version);
free(version);
nix_gc_decref(NULL, value);
nix_state_free(state);
nix_store_free(store);
return 0;
}
```