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| author | Sean McArthur <sean.monstar@gmail.com> | 2014-12-20 00:09:35 -0800 |
|---|---|---|
| committer | Sean McArthur <sean.monstar@gmail.com> | 2015-01-06 14:49:42 -0800 |
| commit | 44440e5c18a1dbcc9685866ffffe00c508929079 (patch) | |
| tree | b66c50cd1e471dc0e37b8a0db2cf7f8f28fbac5f /src/libsyntax/ext/format.rs | |
| parent | 8efd9901b628d687d11a4d0ccc153553b38ada49 (diff) | |
| download | rust-44440e5c18a1dbcc9685866ffffe00c508929079.tar.gz rust-44440e5c18a1dbcc9685866ffffe00c508929079.zip | |
core: split into fmt::Show and fmt::String
fmt::Show is for debugging, and can and should be implemented for
all public types. This trait is used with `{:?}` syntax. There still
exists #[derive(Show)].
fmt::String is for types that faithfully be represented as a String.
Because of this, there is no way to derive fmt::String, all
implementations must be purposeful. It is used by the default format
syntax, `{}`.
This will break most instances of `{}`, since that now requires the type
to impl fmt::String. In most cases, replacing `{}` with `{:?}` is the
correct fix. Types that were being printed specifically for users should
receive a fmt::String implementation to fix this.
Part of #20013
[breaking-change]
Diffstat (limited to 'src/libsyntax/ext/format.rs')
| -rw-r--r-- | src/libsyntax/ext/format.rs | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/libsyntax/ext/format.rs b/src/libsyntax/ext/format.rs index 1f39555f496..4638500ebf4 100644 --- a/src/libsyntax/ext/format.rs +++ b/src/libsyntax/ext/format.rs @@ -607,7 +607,7 @@ impl<'a, 'b> Context<'a, 'b> { let trait_ = match *ty { Known(ref tyname) => { match tyname[] { - "" => "Show", + "" => "String", "?" => "Show", "e" => "LowerExp", "E" => "UpperExp", |