On Sat, Apr 25, 2020 at 11:17:25AM +0200, Hartmut Goebel wrote:
> Hi,
> 
> in Cargo (to my experience) most versions are defined as "caret
> versions, specifying the minimum version. According to the Cargo Book
> these version dependence [1] are defined like this (my words):
> 
> Newer version of a package can be used, as long as the left-most
> non-zero digit in the version keeps the same. This means: If a package
> requires ^1.3, it might also use 1.4, 1.5, etc. Whereas a package
> requiring ^0.5.7 must only use 0.5.8, etc. but not 0.6.x
> 
> This it should be save to update e.g. unicode-segmentation 1.3 to 1.6 -
> as long as no package requires an exact version.
> 
> I propose the following:
> 
>  1.
> 
>     Variables names for rust packages shall only define the left-most
>     non-zero digit (and any leading zeros, of course).
> 
>     Examples: rust-url-1, rust-url-2, rust-bytes-0.4, rust-bytes-0.5
> 
>  2.
> 
>     Packages using caret version requirements shall refer to the
>     respective variable.
> 
>     Example: requirements "url ^1.5" -> rust-url-1; "bytes ^0.4.8" ->
>     rust-bytes-0.4
> 
>  3.
> 
>     If a package requires e specific version, the variable shall contain
>     this specific version and a "alias define" shall refer to this
>     package if it is the highes "caret" version in guix.
> 
>     Example 1: Some package requires "bakery =1.2", with "bakery" not
>     being in guix yet. Then the new package "bakery@1.2.3" will be
>     defined as "rust-bakery-1.2" and additionally "(define-public
>     rust-bakery-1 rust-bakery-1.2")
>     Example 2: Later, if some package requires  "bakery ^1.3",
>     "rust-bakery-1" will (directly) define "bakery@1.3.0".
> 
> Above rule shall go into the packaging guide in the manual. Variables
> shall be renamed accordingly.
> 
> Rational:
> 
>  1. Using only the left-most non-zero digit in the variable name follows
>     the version scheme intended by Cargo.
>  2. Referring to variable names build like this eases updating, since
>     only the package itself needs to be updated, not the all occurrences
>     of the variable name.
>  3. Distinguishing in dependencies between variable names build like
>     this and more specific ones makes it easy to spot whether some
>     package requires a *specific* version of another package, or whether
>     it is (expected to be) save to upgrade the other package.
> 
> WDTY?
> 
> [1]
> https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html#caret-requirements
> 

I like this idea. It makes updating rust crates easier and removes a
bunch of extra ones that aren't actually needed.

-- 
Efraim Flashner   <efraim@flashner.co.il>   אפרים פלשנר
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