Discussion Thread: DIP 1032--Function pointers and Delegate Parameters...--Community Review Round 1

[tsbockman]

On Saturday, 4 April 2020 at 11:40:26 UTC, H. S. Teoh wrote:
> ...
> IOW, the effective attributes of a function call is the least 
> permissive among the function itself and its delegate arguments.

This is exactly the behaviour that I want.

In general, every function should be annotated by default with 
the the strongest gaurantees which the compiler can verify that 
it actually fulfills. There are only two exceptions to this rule, 
I think:

A) When insufficient information is available to the compiler to 
determine if a restrictive (strong gaurantee) attribute applies, 
the programmer may need to supply the right answer explicitly, as 
in the case of @trusted, or of abstract and extern functions 
whose body is not available for analysis.

B) When the author of a public API chooses to explicitly relax 
these gaurantees in order to avoid exposing private 
implementation details and accidentally turning changes to 
otherwise encapsulated details into breaking API changes.

Currently, I find D's rules for attribute defaults and scoping so 
far out of sync with the logical system above that I've mostly 
given up on it and just explicitly annotate EVERYTHING I can. 
This is fairly painful due to the visual noise and the lack of 
negative attributes like "impure".

The semantics of D's attribute system are great - a major selling 
point of the language, to me - but the syntax is terribly 
awkward, verbose, and inconsistent.