diff --git a/src/libcore/fmt/mod.rs b/src/libcore/fmt/mod.rs index 5820fe58932c6..1dc0faa156d69 100644 --- a/src/libcore/fmt/mod.rs +++ b/src/libcore/fmt/mod.rs @@ -1202,6 +1202,23 @@ impl<'a> Formatter<'a> { /// is longer than this length /// /// Notably this function ignores the `flag` parameters. + /// + /// # Examples + /// + /// ``` + /// use std::fmt; + /// + /// struct Foo; + /// + /// impl fmt::Display for Foo { + /// fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + /// formatter.pad("Foo") + /// } + /// } + /// + /// assert_eq!(&format!("{:<4}", Foo), "Foo "); + /// assert_eq!(&format!("{:0>4}", Foo), "0Foo"); + /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn pad(&mut self, s: &str) -> Result { // Make sure there's a fast path up front @@ -1368,7 +1385,7 @@ impl<'a> Formatter<'a> { self.buf.write_str(data) } - /// Writes some formatted information into this instance + /// Writes some formatted information into this instance. #[stable(feature = "rust1", since = "1.0.0")] pub fn write_fmt(&mut self, fmt: Arguments) -> Result { write(self.buf, fmt) @@ -1381,11 +1398,69 @@ impl<'a> Formatter<'a> { or `sign_aware_zero_pad` methods instead")] pub fn flags(&self) -> u32 { self.flags } - /// Character used as 'fill' whenever there is alignment + /// Character used as 'fill' whenever there is alignment. + /// + /// # Examples + /// + /// ``` + /// use std::fmt; + /// + /// struct Foo; + /// + /// impl fmt::Display for Foo { + /// fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + /// let c = formatter.fill(); + /// if let Some(width) = formatter.width() { + /// for _ in 0..width { + /// write!(formatter, "{}", c)?; + /// } + /// Ok(()) + /// } else { + /// write!(formatter, "{}", c) + /// } + /// } + /// } + /// + /// // We set alignment to the left with ">". + /// assert_eq!(&format!("{:G>3}", Foo), "GGG"); + /// assert_eq!(&format!("{:t>6}", Foo), "tttttt"); + /// ``` #[stable(feature = "fmt_flags", since = "1.5.0")] pub fn fill(&self) -> char { self.fill } - /// Flag indicating what form of alignment was requested + /// Flag indicating what form of alignment was requested. + /// + /// # Examples + /// + /// ``` + /// #![feature(fmt_flags_align)] + /// + /// extern crate core; + /// + /// use std::fmt; + /// use core::fmt::Alignment; + /// + /// struct Foo; + /// + /// impl fmt::Display for Foo { + /// fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + /// let s = match formatter.align() { + /// Alignment::Left => "left", + /// Alignment::Right => "right", + /// Alignment::Center => "center", + /// Alignment::Unknown => "into the void", + /// }; + /// write!(formatter, "{}", s) + /// } + /// } + /// + /// fn main() { + /// assert_eq!(&format!("{:<}", Foo), "left"); + /// assert_eq!(&format!("{:>}", Foo), "right"); + /// assert_eq!(&format!("{:^}", Foo), "center"); + /// assert_eq!(&format!("{}", Foo), "into the void"); + /// } + /// ``` #[unstable(feature = "fmt_flags_align", reason = "method was just created", issue = "27726")] pub fn align(&self) -> Alignment {