error: add errmsg_raw utility

This commit is contained in:
anna 2021-07-30 15:50:35 +02:00
parent 9fef6c5a6d
commit 87d0a30dab
Signed by: fef
GPG Key ID: EC22E476DC2D3D84
2 changed files with 38 additions and 5 deletions

View File

@ -51,7 +51,7 @@ void error_demo(void)
catch(&err) {
/* this will only be executed if the callee yeeted an error */
printf(" fails() failed with code %u: %s\n",
errnum(&err), nstr_raw(errmsg(&err)));
errnum(&err), errmsg_raw(&err));
/*
* you always need to call errput() in the outermost function,
@ -67,7 +67,7 @@ void error_demo(void)
succeeds(2, &err);
catch(&err) {
printf(" succeeds() failed with code %u: %s\n",
errnum(&err), nstr_raw(errmsg(&err)));
errnum(&err), errmsg_raw(&err));
errput(&err);
}
@ -75,7 +75,7 @@ void error_demo(void)
chain(3, &err);
catch(&err) {
printf(" chain() failed with code %u: %s\n",
errnum(&err), nstr_raw(errmsg(&err)));
errnum(&err), errmsg_raw(&err));
errput(&err);
}
}

View File

@ -8,6 +8,27 @@
/**
* @defgroup error Error Handling
*
* libneo has a standardized way of handling errors: If a function is somehow
* able to fail at runtime, for example because of invalid parameters or lack of
* system resources, it accepts an argument of type `error *` which is usually
* the last one in the parameter list. When such a function is called and it
* encounters a runtime error, it `yeet()`s that error, does cleanup work if
* required, and then returns an undefined value. If the function call was
* successful, this is indicated by `neat()`. Functions accepting an `error *`
* parameter **MUST** always call either `yeet()` or `neat()`, but not both.
*
* If you call such a function, you have two options. If you don't want to deal
* with error handling, you can simply pass in `nil`, which will print the error
* message to stderr and cause the program to terminate if an error is
* `yeet()`ed. This is useful for quick prototyping and situations where
* encountering an error would be so critical that your program would need to
* halt anyway. To actually handle errors, you declare a local variable of type
* `error` and pass its address to the function. Then, immediately after the
* call, use the `catch()` macro to handle the error. In the error handler,
* you must call `errput()` to release resources attached to the error.
*
* See `demo/error.c` in the source code repository for examples.
*
* @{
*/
@ -57,7 +78,7 @@ void errput(error *err);
* by `err` is an actual error, i.e. it has been `yeet()`ed to.
* Resources for the error must be released using `errput()`.
*/
#define ncatch(err) if ((err) != nil && (err)->_number != 0)
#define ncatch(err) if ((err) != nil && (err)->_number + 1 >= 2)
#ifndef __cplusplus
/**
* @brief Catch an error.
@ -86,7 +107,19 @@ void errput(error *err);
* @param err `error *` to get the message of
* @returns The error message, may be `nil`
*/
#define errmsg(err) ((err) == nil ? (nstr_t *)nil : (err)->_message)
#define errmsg(err) ((err) == nil ? (nstr_t *)0 : (err)->_message)
/**
* @brief Get an optional error message as a raw C string.
*
* @param err `error *` to get the message of
* @returns The error message as a `const char *`, may be `nil`
*/
#define errmsg_raw(err) ( \
( (err) != nil && (err)->_message != nil ) \
? nstr_raw((err)->_message) \
: (const char *)0 \
)
/** @} */