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I don't agree it is at the prototyping level... I think C++ is quite far ahead there than Rust IMO... For a 'stable' production implementation after prototypin

by berkut 5y ago

I don't agree it is at the prototyping level... I think C++ is quite far ahead there than Rust IMO... For a 'stable' production implementation after prototyping, I agree that the benefits Rust provides (if it compiles, it will either panic or work) are well worth it, and so longer-term, I buy that you probably will spend less time, but in my experience, things like not being able to specify default field values inline (you need to provide a 'new' function, or 'default' impl, meaning you then have very tightly-coupled parts in different places in the code) compared to C++11's member variable inline initialisation is very fustrating when in the early stages of prototyping, when things are changing a lot. Similarly, as mentioned above - string handling, with as_str(), to_string(), String::new(), from(), etc, I think make some sense at a full production level when you might care about ownership / copies / allocations, and want them to be explicit, but when you're just prototyping stuff to work out data structures and relationships, it's increadibly annoying IMO when you're refactoring.

zozbot234 5y ago
> things like not being able to specify default field values inline Rust's "struct update syntax" can be reused to do this. `MyStruct { my_field: 42, ..my_local_defaults }`, where my_local_defaults is an instance of MyStruct that's in scope.
- berkut 5y ago
  That's not what I meant by inline. In C++, you can set the default at the same time as you declare the member variable, meaning the three things (variable type, variable name and variable default) are in exactly the same place in the code on the same line. In Rust, you can't do this, you need to implement new() or default() (or manually specify all field items when declaring the struct), which is normally in another place in the code, so you have tightly-coupled code in two places, which is as bad as C++ headers and implementation files which is what a lot of Rust evangelists seem to complain about on here about C++ (it's a valid complaint, but I don't think Rust completely gets it right, as is complicates / makes things more verbose in other ways like this one).
nicoburns 5y ago
> things like not being able to specify default field values inline I’m cautiously optimistic that Rust will get this at some point. There’s quite a lot of demand for this in the Rust community (although some opposition too)

by berkut 5y ago

zozbot234 5y ago

> things like not being able to specify default field values inline Rust's "struct update syntax" can be reused to do this. `MyStruct { my_field: 42, ..my_local_defaults }`, where my_local_defaults is an instance of MyStruct that's in scope.

berkut 5y ago
That's not what I meant by inline. In C++, you can set the default at the same time as you declare the member variable, meaning the three things (variable type, variable name and variable default) are in exactly the same place in the code on the same line. In Rust, you can't do this, you need to implement new() or default() (or manually specify all field items when declaring the struct), which is normally in another place in the code, so you have tightly-coupled code in two places, which is as bad as C++ headers and implementation files which is what a lot of Rust evangelists seem to complain about on here about C++ (it's a valid complaint, but I don't think Rust completely gets it right, as is complicates / makes things more verbose in other ways like this one).

nicoburns 5y ago

> things like not being able to specify default field values inline I’m cautiously optimistic that Rust will get this at some point. There’s quite a lot of demand for this in the Rust community (although some opposition too)