Problems with C++ exceptions
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Problems with C++ exceptions
1–10 of 112 posts
Re: Problems with C++ exceptions
#2Java and Rust are the only language that I know of that has proper handling of exceptions; mandatory declaration as part of method declaration, since exceptions ARE an integral part of the contract. (Yes, I consider the Result being corresponding to exception declaration, since the return value MUST be checked prior to use of T.)
Re: Problems with C++ exceptions
#3Java and Rust are the only language that I know of that has proper handling of exceptions; mandatory declaration as part of method declaration, since exceptions ARE an integral part of the contract. (Yes, I consider the Result being corresponding to exception declaration, since the return value MUST be checked prior to use of T.)
Swift user here: I have to say one of the best features of Swift is the exception handling. Which is to say, exceptions in Swift are not C++/Java/Obj-C style exceptions, but instead are a way to return an error result from a function. And Swift enforces that the error is handled.
That is, a `throw` statement in Swift simply returns an `Error` value to the caller via a special return path instead of the normal result.
More explicitly, a Swift function declared as:
func f() throws -> T {
}
func f() -> (T|any Error) {
}
Re: Problems with C++ exceptions
#4Honestly, I thought the diatribe would focus on needless complexity.
The starting example is how I'd do it in C:
```
void f(const char* p) // unsafe, naive use
{
FILE \*f = fopen(p, "r"); // acquire
// use f
fclose(f); // release
```
Wouldn't the simpler solution be ensuring your function doesn't exit before release? All that c++ destroyer stuff appears somewhat unnecessary and as the author points out, creates even more problems.
Re: Problems with C++ exceptions
#5The classic "Frequently Questioned Answers" is the ultimate takedown of this abomination of a language.
Re: Problems with C++ exceptions
#6Author completely misunderstands how to use exceptions and is just bashing them. A lot of what he says is inaccurate if not outwardly incorrect.
Also Bjarne's control of C++ is quite limited, and he is semi-retired, so asking him to "fix his language" is fairly misguided. It's designed by a committee of 200+ people.
Anyway what you want seems to be to not use exceptions, but monads instead. These are also part of the standard, it's called std::expected.
Re: Problems with C++ exceptions
#7This is a common problem with try-catch syntax. An alternative, and arguably more useful syntax would be
try (File_handle fh {s, "r"}) {
// use fh
} unless (const File_error& e) {
// handle error
}
Re: Problems with C++ exceptions
#8Honestly, I thought the diatribe would focus on needless complexity. The starting example is how I'd do it in C: ``` void f(const char* p) // unsafe, naive use { FILE \*f = fopen(p, "r"); // acquire // use f fclose(f); // release } ``` Wouldn't the simpler solution be ensuring your function doesn't exit before release? All that c++ destroyer stuff appears somewhat unnecessary and as the author points out, creates eve…
That means you cannot use early exit, and all your variables must be checked as to whether they were initialized (which on top of the checks might also require further state).
Re: Problems with C++ exceptions
#9Java and Rust are the only language that I know of that has proper handling of exceptions; mandatory declaration as part of method declaration, since exceptions ARE an integral part of the contract. (Yes, I consider the Result being corresponding to exception declaration, since the return value MUST be checked prior to use of T.)
Swift user here: I have to say one of the best features of Swift is the exception handling. Which is to say, exceptions in Swift are not C++/Java/Obj-C style exceptions, but instead are a way to return an error result from a function. And Swift enforces that the error is handled. That is, a `throw` statement in Swift simply returns an `Error` value to the caller via a special return path instead of the normal result.…
I saw that in Swift, a method can declare it throws an exception, but it doesn't (can't) declare the exception _type_. I'm not a regular user of Swift (I usually use Java - I'm not sure what other languages you are familiar with), but just thinking about it: isn't it strange that you don't know the exception type? Isn't this kind of like an untyped language, where you have to read the documentation on what a method can return? Isn't this a source of errors itself, in practise?
Re: Problems with C++ exceptions
#10Author completely misunderstands how to use exceptions and is just bashing them. A lot of what he says is inaccurate if not outwardly incorrect. Also Bjarne's control of C++ is quite limited, and he is semi-retired, so asking him to "fix his language" is fairly misguided. It's designed by a committee of 200+ people. Anyway what you want seems to be to not use exceptions, but monads instead. These are also part of the…
Agreed. Author is trying to mix paradigms. Simplest approach if they want local handling and non-propagation of errors is to just have the file holder not check for open success, and check that manually after construction. Then you get guaranteed closure of file no matter how the function is exited.
class File_handle {
FILE *p;
public:
File_handle(const char *pp, const char *r) { p = fopen(pp, r); }
~File_handle() { if ( p ) fclose(p); }
FILE* file() const { return p; }
};
void f(string s)
{
File_handle fh { s, "r"};
if ( fh.file() == NULL ) {
fprintf(stderr, "failed to open file '%s', error=%d\n", p, errno);
return;
}
// use fh
}