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<!DOCTYPE html> < html lang = "en" > < head > < meta charset = "utf-8" > < meta name = "viewport" content = "width=device-width, initial-scale=1.0" > < meta name = "generator" content = "rustdoc" > < meta name = "description" content = "Formatting macro for constructing `Ident`s." > < title > format_ident in quote - Rust< / title > < script > if ( window . location . protocol !== "file:" ) document . head . insertAdjacentHTML ( "beforeend" , "SourceSerif4-Regular-46f98efaafac5295.ttf.woff2,FiraSans-Regular-018c141bf0843ffd.woff2,FiraSans-Medium-8f9a781e4970d388.woff2,SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2,SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2" . split ( "," ) . map ( f => ` <link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/ ${ f } "> ` ) . join ( "" ) ) < / script > < link rel = "stylesheet" href = "../static.files/normalize-76eba96aa4d2e634.css" > < link rel = "stylesheet" href = "../static.files/rustdoc-dd39b87e5fcfba68.css" > < meta name = "rustdoc-vars" data-root-path = "../" data-static-root-path = "../static.files/" data-current-crate = "quote" data-themes = "" data-resource-suffix = "" data-rustdoc-version = "1.80.0 (051478957 2024-07-21)" data-channel = "1.80.0" data-search-js = "search-d52510db62a78183.js" data-settings-js = "settings-4313503d2e1961c2.js" > < script src = "../static.files/storage-118b08c4c78b968e.js" > < / script > < script defer src = "sidebar-items.js" > < / script > < script defer src = "../static.files/main-20a3ad099b048cf2.js" > < / script > < noscript > < link rel = "stylesheet" href = "../static.files/noscript-df360f571f6edeae.css" > < / noscript > < link rel = "alternate icon" type = "image/png" href = "../static.files/favicon-32x32-422f7d1d52889060.png" > < link rel = "icon" type = "image/svg+xml" href = "../static.files/favicon-2c020d218678b618.svg" > < / head > < body class = "rustdoc macro" > <!-- [if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif] --> < nav class = "mobile-topbar" > < button class = "sidebar-menu-toggle" title = "show sidebar" > < / button > < / nav > < nav class = "sidebar" > < div class = "sidebar-crate" > < h2 > < a href = "../quote/index.html" > quote< / a > < span class = "version" > 1.0.36< / span > < / h2 > < / div > < div class = "sidebar-elems" > < / div > < / nav > < div class = "sidebar-resizer" > < / div > < main > < div class = "width-limiter" > < rustdoc-search > < / rustdoc-search > < section id = "main-content" class = "content" > < div class = "main-heading" > < h1 > Macro < a href = "index.html" > quote< / a > ::< wbr > < a class = "macro" href = "#" > format_ident< / a > < button id = "copy-path" title = "Copy item path to clipboard" > Copy item path< / button > < / h1 > < span class = "out-of-band" > < a class = "src" href = "../src/quote/format.rs.html#111-125" > source< / a > · < button id = "toggle-all-docs" title = "collapse all docs" > [< span > − < / span > ]< / button > < / span > < / div > < pre class = "rust item-decl" > < span class = "macro" > macro_rules!< / span > format_ident {
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(< span class = "macro-nonterminal" > $fmt< / span > :expr) => { ... };
(< span class = "macro-nonterminal" > $fmt< / span > :expr, $(< span class = "macro-nonterminal" > $rest< / span > :tt)< span class = "kw-2" > *< / span > ) => { ... };
}< / pre > < details class = "toggle top-doc" open > < summary class = "hideme" > < span > Expand description< / span > < / summary > < div class = "docblock" > < p > Formatting macro for constructing < code > Ident< / code > s.< / p >
< br >
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< h2 id = "syntax" > < a class = "doc-anchor" href = "#syntax" > §< / a > Syntax< / h2 >
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< p > Syntax is copied from the < a href = "https://doc.rust-lang.org/1.80.0/alloc/macro.format.html" title = "macro alloc::format" > < code > format!< / code > < / a > macro, supporting both positional and
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named arguments.< / p >
< p > Only a limited set of formatting traits are supported. The current mapping
of format types to traits is:< / p >
< ul >
< li > < code > {}< / code > ⇒ < a href = "trait.IdentFragment.html" title = "trait quote::IdentFragment" > < code > IdentFragment< / code > < / a > < / li >
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< li > < code > {:o}< / code > ⇒ < a href = "https://doc.rust-lang.org/1.80.0/core/fmt/trait.Octal.html" title = "trait core::fmt::Octal" > < code > Octal< / code > < / a > < / li >
< li > < code > {:x}< / code > ⇒ < a href = "https://doc.rust-lang.org/1.80.0/core/fmt/trait.LowerHex.html" title = "trait core::fmt::LowerHex" > < code > LowerHex< / code > < / a > < / li >
< li > < code > {:X}< / code > ⇒ < a href = "https://doc.rust-lang.org/1.80.0/core/fmt/trait.UpperHex.html" title = "trait core::fmt::UpperHex" > < code > UpperHex< / code > < / a > < / li >
< li > < code > {:b}< / code > ⇒ < a href = "https://doc.rust-lang.org/1.80.0/core/fmt/trait.Binary.html" title = "trait core::fmt::Binary" > < code > Binary< / code > < / a > < / li >
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< / ul >
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< p > See < a href = "https://doc.rust-lang.org/1.80.0/alloc/fmt/index.html" title = "mod alloc::fmt" > < code > std::fmt< / code > < / a > for more information.< / p >
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< br >
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< h2 id = "identfragment" > < a class = "doc-anchor" href = "#identfragment" > §< / a > IdentFragment< / h2 >
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< p > Unlike < code > format!< / code > , this macro uses the < a href = "trait.IdentFragment.html" title = "trait quote::IdentFragment" > < code > IdentFragment< / code > < / a > formatting trait by
default. This trait is like < code > Display< / code > , with a few differences:< / p >
< ul >
< li > < code > IdentFragment< / code > is only implemented for a limited set of types, such as
unsigned integers and strings.< / li >
< li > < a href = "../proc_macro2/struct.Ident.html" title = "struct proc_macro2::Ident" > < code > Ident< / code > < / a > arguments will have their < code > r#< / code > prefixes stripped, if present.< / li >
< / ul >
< br >
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< h2 id = "hygiene" > < a class = "doc-anchor" href = "#hygiene" > §< / a > Hygiene< / h2 >
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< p > The < a href = "../proc_macro2/struct.Span.html" title = "struct proc_macro2::Span" > < code > Span< / code > < / a > of the first < code > Ident< / code > argument is used as the span of the final
identifier, falling back to < a href = "../proc_macro2/struct.Span.html#method.call_site" title = "associated function proc_macro2::Span::call_site" > < code > Span::call_site< / code > < / a > when no identifiers are
provided.< / p >
< div class = "example-wrap" > < pre class = "rust rust-example-rendered" > < code > < span class = "comment" > // If `ident` is an Ident, the span of `my_ident` will be inherited from it.
< / span > < span class = "kw" > let < / span > my_ident = < span class = "macro" > format_ident!< / span > (< span class = "string" > "My{}{}"< / span > , ident, < span class = "string" > "IsCool"< / span > );
< span class = "macro" > assert_eq!< / span > (my_ident, < span class = "string" > "MyIdentIsCool"< / span > );< / code > < / pre > < / div >
< p > Alternatively, the span can be overridden by passing the < code > span< / code > named
argument.< / p >
< div class = "example-wrap" > < pre class = "rust rust-example-rendered" > < code > < span class = "kw" > let < / span > my_span = < span class = "comment" > /* ... */< / span > ;
< span class = "macro" > format_ident!< / span > (< span class = "string" > "MyIdent"< / span > , span = my_span);< / code > < / pre > < / div >
< p > < br > < / p >
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< h2 id = "panics" > < a class = "doc-anchor" href = "#panics" > §< / a > Panics< / h2 >
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< p > This method will panic if the resulting formatted string is not a valid
identifier.< / p >
< br >
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< h2 id = "examples" > < a class = "doc-anchor" href = "#examples" > §< / a > Examples< / h2 >
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< p > Composing raw and non-raw identifiers:< / p >
< div class = "example-wrap" > < pre class = "rust rust-example-rendered" > < code > < span class = "kw" > let < / span > my_ident = < span class = "macro" > format_ident!< / span > (< span class = "string" > "My{}"< / span > , < span class = "string" > "Ident"< / span > );
< span class = "macro" > assert_eq!< / span > (my_ident, < span class = "string" > "MyIdent"< / span > );
< span class = "kw" > let < / span > raw = < span class = "macro" > format_ident!< / span > (< span class = "string" > "r#Raw"< / span > );
< span class = "macro" > assert_eq!< / span > (raw, < span class = "string" > "r#Raw"< / span > );
< span class = "kw" > let < / span > my_ident_raw = < span class = "macro" > format_ident!< / span > (< span class = "string" > "{}Is{}"< / span > , my_ident, raw);
< span class = "macro" > assert_eq!< / span > (my_ident_raw, < span class = "string" > "MyIdentIsRaw"< / span > );< / code > < / pre > < / div >
< p > Integer formatting options:< / p >
< div class = "example-wrap" > < pre class = "rust rust-example-rendered" > < code > < span class = "kw" > let < / span > num: u32 = < span class = "number" > 10< / span > ;
< span class = "kw" > let < / span > decimal = < span class = "macro" > format_ident!< / span > (< span class = "string" > "Id_{}"< / span > , num);
< span class = "macro" > assert_eq!< / span > (decimal, < span class = "string" > "Id_10"< / span > );
< span class = "kw" > let < / span > octal = < span class = "macro" > format_ident!< / span > (< span class = "string" > "Id_{:o}"< / span > , num);
< span class = "macro" > assert_eq!< / span > (octal, < span class = "string" > "Id_12"< / span > );
< span class = "kw" > let < / span > binary = < span class = "macro" > format_ident!< / span > (< span class = "string" > "Id_{:b}"< / span > , num);
< span class = "macro" > assert_eq!< / span > (binary, < span class = "string" > "Id_1010"< / span > );
< span class = "kw" > let < / span > lower_hex = < span class = "macro" > format_ident!< / span > (< span class = "string" > "Id_{:x}"< / span > , num);
< span class = "macro" > assert_eq!< / span > (lower_hex, < span class = "string" > "Id_a"< / span > );
< span class = "kw" > let < / span > upper_hex = < span class = "macro" > format_ident!< / span > (< span class = "string" > "Id_{:X}"< / span > , num);
< span class = "macro" > assert_eq!< / span > (upper_hex, < span class = "string" > "Id_A"< / span > );< / code > < / pre > < / div >
< / div > < / details > < / section > < / div > < / main > < / body > < / html >
