[Lldb-commits] [PATCH] D58792: Add "operator bool" to SB APIs

Shafik Yaghmour via Phabricator via lldb-commits lldb-commits at lists.llvm.org
Fri Mar 1 14:29:19 PST 2019


shafik added a comment.

In D58792#1415390 <https://reviews.llvm.org/D58792#1415390>, @clayborg wrote:

> In D58792#1414964 <https://reviews.llvm.org/D58792#1414964>, @labath wrote:
>
> > In D58792#1414191 <https://reviews.llvm.org/D58792#1414191>, @shafik wrote:
> >
> > > It stood out to me that some of the conversions were not `const` and I can see that `IsValid` is not consistently `const` across the API but after talking to @jingham it is unfortunately something we can't change.
> >
> >
> > Yes, that is unfortunate. I can think of three things that we could do differently though:
> >
> > 1. add a `const` version of `IsValid` where it is missing, and have and always-const `operator bool` which uses that
> > 2. give up on constness and just have a non-const `operator bool` everywhere
> > 3. add a const `operator bool` everywhere, and have `IsValid` (const or non-const) call into that
>
>
> "const" is useless when your class contains a shared pointer or a unique pointer. It also changes the API mangling which we can't do. So I vote for give up on const as you can call non const methods in any shared and unique pointers because const is only protecting the pointer from changing.
>
> > Each option has different tradeoffs, and it's not really clear to me which one is better. I am happy to implement whichever you think is best.


The goal of `const` is to communicate to the user that it does not mutate the underlying object, which in general is good practice to maintain if possible.

In this case I don't see any good trade-offs here. I don't feel like adding a `const` version along w/ a non-`const` version really helps since it still muddies the waters.


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