lazy_format

What started as a simple collection of cleanup changes eventually spiraled out to the complete implementation of everything I've been looking to do for lazy_format 2.0. In particular, the improvements to if necessitated minor but technically backwards incompatible macro changes, which presented the opportunity to make the other backwards incompatible changes, like removing deprecated functionality and simplifying macro definitions. In general, if you're only using lazy_format and you aren't using horrorshow, you shouldn't experience any breakages in the upgrade.

Added

• lazy_format now supports implicit named parameters. Because we use format_args! internally, this support came automatically
• lazy_format's if, match, and for syntaxes now allow for unparenthesized format literals, in cases where there's no arguments.

Changed

• lazy_format's if conditional version now allows omitting the else branch, in which case it will simply write nothing if none of the other if / else if branches match.
• lazy_format's else branch now requires the => syntax, for consistency (previously it was optional).
• Upgrade to Edition 2021. This means we can use the new pat pattern, which correctly handles nested | in patterns. This allows for much simpler macro definitions in a way that's fully backwards compatible (aside from the increased MSRV).

Removed

• Breaking Removed semi_lazy_format; the complexity of its implementation wasn't worth the added functionality. Instead, callers should manually evaluate any parameters they want to be eagerly evaluated before calling lazy_format and then pass them manually.
• Breaking Removed horrorshow feature, due to potential buggy interactions with transitive dependencies. Prefer instead to create a display adapter which connects Display to horrorshow.
• Breaking semi_lazy_format! no longer supports the deprecated fmt => body syntax; it now must use the |fmt| body syntax.

Fixed

• Fixed potential issue with ambiguous method call in the for loop version of lazy_format

Added

• make_lazy_format! now has a closure-like syntax, using |f| { ... } instead of f => { ... }. The older syntax is retained for backwards compatibility.

Fixed

• Fix an issue where formatting without arguments (e.g, lazy_format!("{}")) would succeed incorrectly (#5).
  • Thanks @ten0 for the report.

• Changelog started

Fix horrorshow implementation & borrows

Real fix for the cargo feature issue FOR REAL

Real fix for the cargo feature issue

• Add horrorshow as an optional dependency. When enabled, lazy_format
  objects implement horrorshow::render.
• Add test, rustdoc