pub struct DebugStruct<'a, 'b: 'a> { /* private fields */ }Expand description
A struct to help with fmt::Debug implementations.
This is useful when you wish to output a formatted struct as a part of your
Debug::fmt implementation.
This can be constructed by the Formatter::debug_struct method.
§Examples
use std::fmt;
struct Foo {
    bar: i32,
    baz: String,
}
impl fmt::Debug for Foo {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_struct("Foo")
           .field("bar", &self.bar)
           .field("baz", &self.baz)
           .finish()
    }
}
assert_eq!(
    format!("{:?}", Foo { bar: 10, baz: "Hello World".to_string() }),
    r#"Foo { bar: 10, baz: "Hello World" }"#,
);Implementations§
Source§impl<'a, 'b: 'a> DebugStruct<'a, 'b>
 
impl<'a, 'b: 'a> DebugStruct<'a, 'b>
1.2.0 · Sourcepub fn field(&mut self, name: &str, value: &dyn Debug) -> &mut Self
 
pub fn field(&mut self, name: &str, value: &dyn Debug) -> &mut Self
Adds a new field to the generated struct output.
§Examples
use std::fmt;
struct Bar {
    bar: i32,
    another: String,
}
impl fmt::Debug for Bar {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_struct("Bar")
           .field("bar", &self.bar) // We add `bar` field.
           .field("another", &self.another) // We add `another` field.
           // We even add a field which doesn't exist (because why not?).
           .field("nonexistent_field", &1)
           .finish() // We're good to go!
    }
}
assert_eq!(
    format!("{:?}", Bar { bar: 10, another: "Hello World".to_string() }),
    r#"Bar { bar: 10, another: "Hello World", nonexistent_field: 1 }"#,
);Sourcepub fn field_with<F>(&mut self, name: &str, value_fmt: F) -> &mut Self
 🔬This is a nightly-only experimental API. (debug_closure_helpers #117729)
pub fn field_with<F>(&mut self, name: &str, value_fmt: F) -> &mut Self
debug_closure_helpers #117729)Adds a new field to the generated struct output.
This method is equivalent to DebugStruct::field, but formats the
value using a provided closure rather than by calling Debug::fmt.
1.53.0 · Sourcepub fn finish_non_exhaustive(&mut self) -> Result
 
pub fn finish_non_exhaustive(&mut self) -> Result
Marks the struct as non-exhaustive, indicating to the reader that there are some other fields that are not shown in the debug representation.
§Examples
use std::fmt;
struct Bar {
    bar: i32,
    hidden: f32,
}
impl fmt::Debug for Bar {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_struct("Bar")
           .field("bar", &self.bar)
           .finish_non_exhaustive() // Show that some other field(s) exist.
    }
}
assert_eq!(
    format!("{:?}", Bar { bar: 10, hidden: 1.0 }),
    "Bar { bar: 10, .. }",
);1.2.0 · Sourcepub fn finish(&mut self) -> Result
 
pub fn finish(&mut self) -> Result
Finishes output and returns any error encountered.
§Examples
use std::fmt;
struct Bar {
    bar: i32,
    baz: String,
}
impl fmt::Debug for Bar {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_struct("Bar")
           .field("bar", &self.bar)
           .field("baz", &self.baz)
           .finish() // You need to call it to "finish" the
                     // struct formatting.
    }
}
assert_eq!(
    format!("{:?}", Bar { bar: 10, baz: "Hello World".to_string() }),
    r#"Bar { bar: 10, baz: "Hello World" }"#,
);Auto Trait Implementations§
impl<'a, 'b> Freeze for DebugStruct<'a, 'b>
impl<'a, 'b> !RefUnwindSafe for DebugStruct<'a, 'b>
impl<'a, 'b> !Send for DebugStruct<'a, 'b>
impl<'a, 'b> !Sync for DebugStruct<'a, 'b>
impl<'a, 'b> Unpin for DebugStruct<'a, 'b>
impl<'a, 'b> !UnwindSafe for DebugStruct<'a, 'b>
Blanket Implementations§
Source§impl<T> BorrowMut<T> for Twhere
    T: ?Sized,
 
impl<T> BorrowMut<T> for Twhere
    T: ?Sized,
Source§fn borrow_mut(&mut self) -> &mut T
 
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more