Worst ideas/features in programming languages?

sarn sarn at theartofmachinery.com
Tue Oct 12 23:13:52 UTC 2021

On Monday, 11 October 2021 at 15:59:10 UTC, Atila Neves wrote:
> I'm brainstorming about what I'll talk about at DConf, and 
> during a conversation with Walter I thought it might be cool to 
> talk about:
> * Worst features implemented in a non-toy language

Go's implicit duck-typing of structs to interfaces.  Things don't 
accidentally match a non-trivial interface, and hardly anyone 
wants to make an interface for a struct that some third party 
manages (just wrapping the struct would more idiomatic for Go).  
For the sake of saving a one-line inheritance specifier, this 
magic makes it so much harder to figure out which structs are 
intended to match an interface in a large codebase written by 
multiple people.

Supporting error detection without helping with error handling.  
Python is good because exceptions inherit from standard types 
that can be handled consistently (e.g., KeyError).  Most other 
languages (including D) aren't much help here.  Go misses the 
point by acting like "if err != nil { return err }" is actually 
handling errors.

I agree with others that C's type declaration syntax is a 
non-feature.  It's pointlessly "clever" and not even consistent.  
I've blogged about this problem here: 

I'm sure you can think of more C++ problems than me, but let me 
pick three that epitomise why I don't like C++ any more:

SFINAE.  It's powerful, but makes template metaprogramming slow 
at compile time, terrible to debug and hard to read.  D shows 
that explicit constraints are better all around.

Member function pointers.  They're hard to use correctly and 
"feel" low level, but are actually very high level.  D's 
delegates are easier to use and reason about, yet are lower level 
(NB: closures are higher level, but that's a different story).

Sensible operator overloading for a simple number-like type takes 
a lot of boring boilerplate, which encourages developers to do 
"interesting" things with operator overloading instead.  D makes 
the sensible things easy, so there's less of a culture of 
"interesting" metaprogramming hacks.

> * Worst features (in your opinion) in D

* The multiple (confusing) ways to write anonymous lambdas.
* opDispatch's (lack of) error handling semantics.
* Autodecoding.
* Overuse of attributes.  (It fills the type system with things 
that could be better done with separate notation for static 
checking tooling.)
* Overloaded semantics of . that makes namespacing hard in 
* The hacky non-virtual destructor implementation.

> * Features you'd like to see in D

Overall, I don't think D needs many more features.  But because 
you asked:

* Better value analysis to make integer promotion issues less 
* Better error handling for opDispatch.
* Native tuple support (with destructuring, etc.).

> Ideas? Examples?
> Thanks!

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