# Struct syn::Generics

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    pub struct Generics {
        pub lt_token: Option<Lt>,
        pub params: Punctuated<GenericParam, Comma>,
        pub gt_token: Option<Gt>,
        pub where_clause: Option<WhereClause>,
    }

Expand description

Lifetimes and type parameters attached to a declaration of a function, enum, trait, etc.

This type is available only if Syn is built with the `"derive"` or `"full"` feature.

## Fields

`lt_token: Option<Lt>``params: Punctuated<GenericParam, Comma>``gt_token: Option<Gt>``where_clause: Option<WhereClause>`

## Implementations

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### impl Generics

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#### pub fn type_params(&self) -> TypeParams<'_>

Returns an `Iterator<Item = &``TypeParam``>` over the type parameters in `self.params`.

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#### pub fn type_params_mut(&mut self) -> TypeParamsMut<'_>

Returns an `Iterator<Item = &mut` `TypeParam``>` over the type parameters in `self.params`.

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#### pub fn lifetimes(&self) -> Lifetimes<'_>

Returns an `Iterator<Item = &``LifetimeDef``>` over the lifetime parameters in `self.params`.

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#### pub fn lifetimes_mut(&mut self) -> LifetimesMut<'_>

Returns an `Iterator<Item = &mut` `LifetimeDef``>` over the lifetime parameters in `self.params`.

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#### pub fn const_params(&self) -> ConstParams<'_>

Returns an `Iterator<Item = &``ConstParam``>` over the constant parameters in `self.params`.

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#### pub fn const_params_mut(&mut self) -> ConstParamsMut<'_>

Returns an `Iterator<Item = &mut` `ConstParam``>` over the constant parameters in `self.params`.

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#### pub fn make_where_clause(&mut self) -> &mut WhereClause

Initializes an empty `where`-clause if there is not one present already.

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### impl Generics

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#### pub fn split_for_impl(
&self
) -> (ImplGenerics<'_>, TypeGenerics<'_>, Option<&WhereClause>)

Split a type’s generics into the pieces required for impl’ing a trait for that type.

    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
    quote! {
        impl #impl_generics MyTrait for #name #ty_generics #where_clause {
            // ...
        }
    }

This method is available only if Syn is built with the `"derive"` or `"full"` feature and the `"printing"` feature.

## Trait Implementations

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### impl Clone for Generics

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#### fn clone(&self) -> Self

Returns a copy of the value. Read more

1.0.0 · source

#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more

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### impl Default for Generics

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#### fn default() -> Self

Returns the “default value” for a type. Read more

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### impl Parse for Generics

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#### fn parse(input: ParseStream<'_>) -> Result<Self>

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### impl ToTokens for Generics

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#### fn to_tokens(&self, tokens: &mut TokenStream)

Write `self` to the given `TokenStream`. Read more

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#### fn to_token_stream(&self) -> TokenStream

Convert `self` directly into a `TokenStream` object. Read more

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#### fn into_token_stream(self) -> TokenStream

Convert `self` directly into a `TokenStream` object. Read more

## Auto Trait Implementations

### impl RefUnwindSafe for Generics

### impl !Send for Generics

### impl !Sync for Generics

### impl Unpin for Generics

### impl UnwindSafe for Generics

## Blanket Implementations

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### impl<T> Any for T where
T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more

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### impl<T> Borrow<T> for T where
T: ?Sized,

const: unstable · source

#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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### impl<T> BorrowMut<T> for T where
T: ?Sized,

const: unstable · source

#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

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### impl<T> From<T> for T

const: unstable · source

#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T where
U: From<T>,

const: unstable · source

#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T> Spanned for T where
T: Spanned + ?Sized,

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#### fn span(&self) -> Span

Returns a `Span` covering the complete contents of this syntax tree node, or `Span::call_site()` if this node is empty. Read more

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### impl<T> ToOwned for T where
T: Clone,

#### type Owned = T

The resulting type after obtaining ownership.

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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more

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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more

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### impl<T, U> TryFrom<U> for T where
U: Into<T>,

#### type Error = Infallible

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.

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### impl<T, U> TryInto<U> for T where
U: TryFrom<T>,

#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.