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To: Proxmox Backup Server development discussion
<pbs-devel@lists.proxmox.com>, Wolfgang Bumiller <w.bumiller@proxmox.com>
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Subject: Re: [pbs-devel] [PATCH proxmox] schema: add const fn
unwrap_*_schema/format methods
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On 22.02.22 09:47, Wolfgang Bumiller wrote:
> 'unwrap_' because they will panic and as `const fn` since
> panic in const fn is now possible
>
> Note that const evaluation will only be triggered when
> actually used in const context, so to ensure *compile time*
> checks, use something like this:
>
> const FOO_SCHEMA: &AllOfSchema =
> SomeType::API_SCHEMA.unwrap_all_of_schema();
> then_use(FOO_SCHEMA);
>
> or to use the list of enum values of an enum string type
> with compile time checks:
>
> const LIST: &'static [EnumEntry] =
> AnEnumStringType::API_SCHEMA
> .unwrap_string_schema()
> .unwrap_format()
> .unwrap_enum_format();
> for values in LIST {
> ...
> }
>
> Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
> ---
> While schemas are usually unlikely to change type or lose properties
> such as enum lists, for `ObjectSchema` and `AllOfSchema` this may
> actually allow catching future issues at build-time...
>
> If we want to do this, I'd prepare a similar patch set for all the
> `ApiHandler::...` value extractions we do in the CLI in pbs (just look
> at the output of `egrep -B1 -nr 'unreachable' ./src ./*/src` in pbs ;-) )
>
IMO the usage gets nicer, lots of removal of unreachable!(), and even if
not used correctly (without const) we're as good as now; so can only win.
If there's no objection from others I'd say: go for it.