Rust macro multiple arguments. How to use multiple macros inside macros in Rust? 1.

Rust macro multiple arguments Dec 13, 2021 · I'm writing an attribute macro and trying to parse arguments passed there. How to pass a format! string and format! arguments to a Rust macro that creates a function? Aug 1, 2020 · Calling functions with different numbers of arguments in Rust macros. ) prints a line to standard output, applying formatting described in std::fmt. By leveraging traits and constraints, you can maintain safety while ensuring your code can operate across various data types. 5. g should pass in the first parameter to f and return a new function. Jun 1, 2016 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand May 27, 2023 · The fundamental syntax for defining a macro in Rust uses the macro_rules! keyword, followed by an identifier and a block of code. The macro_rules! macro supports repetition using the $()* syntax. macro_rules! Note that the previous sentence says "argument", singular—even if a function-like macro is invoked with what looks like multiple arguments: my_func_macro!(15, x + y, f32::consts::PI); the macro itself receives a single argument, which is a stream of parsed tokens. Rust macro is also useful when we need to generate repetitive code. This demo will cover the basics with macro_rules! and using multiple match rules for flexibility with macro usage. You have to define different methods with different names. Here's a basic example: Here's a basic example: macro_rules! hello Dec 30, 2022 · Rust also has no overloaded functions for the same reason. The following should pass --number 5 to command foo . The & is added automatically, similarly to how print! works. Maybe there's a way to loop through all test cases instead of manually defining the amount of tests (like I did), but this is good for now: Sep 18, 2020 · Function-like macros. We Sep 4, 2022 · proc_macro has the real TokenStream type. Macro Repetitions in Rust. Procedural macros: More complex compiled Rust code registered as compiler plugins. The most widely used form of macros in Rust is the declarative macro. I'll start with examples for beginners, then I'll try to cover more advanced examples. Dec 16, 2015 · The count! macro expands to a constant expression that represents the number of arguments it got as input. Jan 18, 2021 · After Peter Hall answer, I was able to achieve what I wanted. Macro parameters types# Macros have different types of parameters inputs that you can use to create your macro, such as: item: an item, like a function, struct, module, etc. println!("{}", "hello");), the parser errors with something like: Jun 25, 2020 · Announcing release 0. 922073 January 5, 2023, 8:10pm 1. As an extreme example, it is possible, though hardly advisable, to implement the Bitwise Cyclic Tag automaton within Rust’s macro system. Pro-macro should be defined detached crate. For example, brackets can be used with the ident token type. Attribute macros attach custom attributes to items, making them useful for adding behaviors to functions, structs, or enums. The Rust standard library includes an assortment of useful macros. How patterns work in macro_rules macros changes slightly: $_:pat in macro_rules now matches usage of | too: e. Jan 5, 2023 · The Rust Programming Language Forum Function like macro with multiple arguments. I tried parsing it as Meta Jun 28, 2020 · I have the same function, written in various different ways that I was testing and bench marking. In general, you can't - Rust does not support variadic functions, except when interoperating with C code that uses varargs. As in general programming with Rust, this is achieved by using generic parameters and traits. Moreover, command! will handle file and tmpname being OsStr correctly, while the manual version would require some modifications. Sep 9, 2021 · I am trying to define a macro_rules macro that will generate struct definitions, which may or may not be generic, and where the types it is generic on may or may not have multiple bounds. Apr 22, 2019 · The Rust Programming Language Forum Yeah, I'm hoping for a way to call the macro with only required arguments and no trailing commas, though: example!(a, b); Dec 12, 2016 · Is it possible to use an argument multiple times in a Rust macros with a single instansiation? 6. Asking for help, clarification, or responding to other answers. println!(format, . As a workaround, you can use tuples to receive multiple values in a single argument. How to pass a macro containing multiple items into a macro? 5. Jan 15, 2025 · Macros allow you to generate code at compile time, saving you from writing repetitive patterns. The specific test cases are expanded in multiple submodules with type May 25, 2017 · Doing this with a macro might look like zip!(Circle, 52, 32, 5). Dec 10, 2020 · Also, regarding the initial question, once a macro input is captured in a metavariable whose kind is not :tt nor :ident, then it gets "wrapped in invisible parenthesis" which prevents it from matching any other literal rule. Everything variadic (like println) is supposed to be solved with macros, to my understanding. Nov 18, 2019 · Reading The Rust Programming Language's chapter on macros says:. Just like when we call functions or macros, we separate multiple parameters Apr 30, 2020 · I don't think that the ability to write Vec i32 vs Vec<i32> is at all worth the burden of extending the core language (and needing to force more work on users trying to parse Rust code, primarily macro authors and other consumers of Rust ASTs). Oct 17, 2015 · @JonHaddad The problem with a compiler plugin is that it can only be used with a nightly compiler. 6. Mar 18, 2022 · I'm trying to create a macro using macro_rules! that would generate a series of structs along with implementations for a given trait. Last optional argument have to accept list of values. Then, it calls the respective "yell" function for that Jan 7, 2021 · No, Rust doesn't support default function arguments. ” At their core, declarative macros allow you to write something similar to a Rust match expression. lib" ); } If you use unsafe linker arguments the you must mark the whole block as unsafe . I believe proc_macro in Rust should help me achieve my requirements. The expression (and pattern in if-let) is parsed as Rust, the inside of {block} is parsed using regular commmand! syntax and can evaluate to multiple arguments (or 0). If you need to count a lot of items and the compiler can't cope with it, see the Counting chapter in The Little Book of Rust Macros, which has more complex macros for counting. ; The new $_:pat_param behaves like $_:pat did before; it does not match (top level) |. Macros may be invoked in the following situations: Expressions and statements; Patterns; Types Jan 7, 2025 · Working with multiple type parameters in Rust allows you to design exceptionally flexible and reusable code, particularly with functions and structs. What are Macros in Rust? A macro in Rust is a way to write code that writes other code. Mar 15, 2022 · The function signatures are the same regarding the parameters. Like: #[macro(Arg1, Arg2)] The issue is that I cannot find the right structure to parse it as. Syn crate. There is no function overloading either, because Rust use function names to derive types (function overloading requires the opposite). )] syntax and declarative macros. It will be very verbose and difficult to work Welcome to Begin Rust. Sep 10, 2017 · I was experimenting with Rust's macro_rules and wanted to make a macro which could parse an HTML like syntax and simply echo the HTML as a string. The inside the parentheses can be any valid Rust expression or a pattern. Or patterns in macro-rules Summary. I wrote: const SIZE: usize = 3; #[derive(Debug)] struct MyVec { dat Nov 2, 2020 · IMO, the main appeal of named parameters is correctness and legibility, in particular in cases where functions take arguments of the same type (e. Feb 8, 2017 · Is it possible to use an argument multiple times in a Rust macros with a single instansiation? 7. 0 relevant settings: (eg. Argument - Plain argument that takes value. We can use the macro with multiple arguments to create a more flexible piece of code. They are especially useful for tasks that require code generation, such as logging, testing or implementing traits for multiple types. Hello World and variables. Jul 16, 2022 · So I thought I'd get my hands dirty and write an actually useful rust macro for the first time(!). Recursive macros are useful for another reason: Each recursive invocation gives you another opportunity to pattern-match the macro’s arguments. iter(). The use case is that I want to initiate a database connection in g and pass it functions that accept a database connection. resorting to iterating over an array or vector with for? Rust has great support for iterators, so you can write something like: endings. I'm having trouble getting even one generic argument to work, because I can't seem to generate PhantomData right macro_rules! Rust provides a powerful macro system that allows metaprogramming. Finally, I think declarative macros make sense when the grammar is simple and easy to define in the grammar DSL. Multi argument - Collection of arguments that accumulates into Vec<T>, there can be only one. Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. g. It's just a helper for the mat! macro. Function-like macros define macros that look like function calls. Apr 28, 2022 · Is it possible to use an argument multiple times in a Rust macros with a single instansiation? 4. Rust macro_rules nested This small crate provides a parameterized_test::create!() macro to simplify creating repeated tests with different arguments. Contribute to Jon-Davis/function_group development by creating an account on GitHub. Jan 27, 2025 · Rust’s Macros: A Tutorial on Creating and Using Custom Macros is a comprehensive guide to creating and utilizing custom macros in Rust. Oct 30, 2024 · This macro generates a hello function that prints a customized message. Note: when working with multiple expansion test files, it is recommended to specify wildcard (*. We call such extensions “macros by example” or simply “macros”. Describe the bug. §Conversion Jan 31, 2017 · As noted by @chris-morgan's answer, expanding the single argument case isn't accounted for. In case of struct initialization you can use the struct update syntax like this: Nov 6, 2023 · i was using a macro, and had no autocomplete for a local interaction variable. It would zip the values, in order, onto the fields of Circle. multiple(true) That means you need a single type to represent your data. There are several ways to handle optional arguments in macros. Sub-command - Propagates rest of arguments to another parser, there ca be only one. Therefore, it should be easy to pass all the arguments that were passed to the public function down into the internal function. Feb 24, 2020 · As per Rust reference: As with let bindings, function arguments are irrefutable patterns, so any pattern that is valid in a let binding is also valid as an argument. Often used for custom derive functionality. So you can specify an argument like: (a, b): (i32, Vec<i32>) just like you would in a let statement. Similarly to macro_rules! macros, they’re more flexible than functions; for example, they can take an unknown number of arguments. How to use multiple macros inside macros in Rust? 1. These are also sometimes referred to as “macros by example,” “macro_rules! macros,” or just plain “macros. Secondly, macros cannot parse the output of other macros. You can then define a trait and implement it for the admissible types of that single argument, and the function will simply delegate to the trait's implementation. A sample of what I've tried: #[macro_export] macro_rules! a_tre A variadic interface takes an arbitrary number of arguments. 1. macro with variable arguments of different types. And I would like to use exactly one patter for that. 73. proc_macro2 is a crate to help testing proc macros, and it has its own TokenStream. For that, we have to parse the function signature through macro input. A macro implementation that just prints (at compile time) the contents of the Multi Option - switch with Vec<T> type, which allows to accumulate multiple values of switch. As you've seen in previous chapters, macros look like functions, except that their name ends with a bang !, but instead of generating a function call, macros are expanded into source code that gets compiled with the rest of the program. This requires eager expansion, which Rust doesn't have. When giving a macro multiple arguments (e. The Rust compiler takes the matched arm and extracts the variable from the argument string. It would typically be used by adding hello_macro!("Rust"); to the main code, and would output Hello, Rust!. As you see, you use (expr) to create an argument (or a part of it) from arbitrary Rust expression and [expr] for multiple arguments. For example, println! can take an arbitrary number of arguments, as determined by the format string. A place for all things related to the Rust programming language—an open-source systems language that emphasizes performance, reliability, and productivity A function overloading macro in rust. The rest of elements should be zero. Here is what I have tried so far: macro_rules! Sep 18, 2016 · Just because it isn't exactly a comma doesn't change matters: a collection of function arguments are not a complete grammar construct. Being able to change argument order is more of a convenience. . We invite you to open a new topic if you have further questions or comments. Multiple tokens can be used with different token types. Jan 15, 2025 · Discover how Rust macros can boost code efficiency and productivity. May 3, 2020 · It'll be much easier to make it a macro. Aug 21, 2022 · To get a little more technical, there is a relatively short list of places where a macro invocation can appear. multiple actual substrings), then iteration is your only option. The idea is to get the file name via the file!() macro and pass it as argument to The windows! macro lets you set multiple arguments at once. I read the macro chapter of Rust by Example, and failed for a while. We can define a macro to accept arguments and repeat the generated code based on those arguments. Examples of declarative macros are vec! , println! or format! . 3 days ago · I am working on a Rust macro that needs to accept the file name as a argument. outside of the macro arguments, i had autocomplete for it. Ask Question Asked 2 years, 11 months ago. Dec 20, 2023 · I have searched the existing issues of tree-sitter-rust; Tree-Sitter CLI Version, if relevant (output of tree-sitter --version) No response. Mar 20, 2024 · Rust have two types of macros, procedural macros which are invoked using the #[derive(. link_args::windows! { stack_size( 0x800000 ); default_lib( "kernel32. Each of those functions lives in it's own module that is named after it's author. Based on the file name I want to parse and do some operations and generate some code. rs // Derive `FromDeriveInput` for this struct, which is a // macro provided by darling to automatically add the ability // to parse argument tokens into the given struct. There are two kinds of macros in Rust: Declarative macros: Created using macro_rules! construct. 1. Jan 17, 2019 · I want to be able to create a higher-order function (called g) that takes in a function (called f). Sep 25, 2023 · In Rust, macros are defined using the macro_rules! keyword, The Builder pattern allows for flexible and fluent construction of complex objects with multiple optional parameters. Nov 14, 2024 · There are multiple types of macros in Rust, but the most common ones are declarative macros (macro_rules!) and procedural macros. Replace your Vec<u8> with a newtype: Aug 13, 2016 · Is it possible to use an argument multiple times in a Rust macros with a single instansiation? 4. Macros are a powerful tool in Rust that allow developers to extend the language itself, creating a more efficient and expressive way of writing code. In this case, since all of your arguments are the same type, you can accept a slice: Dec 2, 2024 · If you want multiple arguments then you can use Incremental TT Munchers like this: Questions about rust macro. Introduction Instructions. Based on pattern matching and replacement. Aug 7, 2016 · Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. – Procedural macros allow creating syntax extensions as execution of a function. 0 of generic-tests, a procedural macro crate providing an attribute that allows the test writer to reuse code between test cases or benchmarks that use the same test protocol with different types under test. ends_with(*n)). If you have an optional argument that can only occur once, then you shouldn't use repetitions: you should instead define multiple patterns in your macro, like this: macro_rules allows users to define syntax extension in a declarative way. Dec 12, 2018 · Can I repeat match in a Rust macro? I want to be able to do something like: my_dsl! { foo <other tokens>; bar <other tokens>; foo <other tokens>; Apr 17, 2020 · The macro have to accept one required argument and three optional arguments. Sometimes it just comes down to personal taste when all other factors are equal. : offset and size, source and destination, x_offset and y_offset, etc). Procedural macros come in one of three flavors: Function-like macros - custom!(); Derive macros - #[derive(CustomDerive)] Sep 2, 2022 · If you need something more complex (e. We can extend our calculate! macro from the previous section to be variadic: The most widely used form of macros in Rust is the declarative macro. How to use multiple macros inside macros in Rust? 3. Here is Apr 10, 2022 · Accept multiple values on proc macro attribute. Rust macro repetition with plus. rs) instead of doing a multiple calls to expand functions for individual files. Note that Rust macros are much safer and more typed than C++ macros, so don't panic about that decision :) – I have a macro that implements a trait, impl_Trait!(). How to use multiple macros inside macros in Rust? Hot Network Questions Sep 7, 2021 · Is it possible to use an argument multiple times in a Rust macros with a single instansiation? 6. Macros can use + in the argument list to indicate that an argument may repeat at least once, or *, to indicate that the argument may repeat zero or more times. The following snippet shows the simplified macro generation for the public function. However, I am facing issues passing file!() as argument to the procedural macro. For more complex parsing such as this, you might want to reach for procedural macros instead. So, we create two crate for example. macro_rules! Rust provides a powerful macro system that allows metaprogramming. takes_value(true). When in doubt, try them all and pick one that you enjoy :) There's plenty of room in the Rust community for multiple implementations! Types of Macros. any(|n| s. First up is a macro called timeit!() which allows you to wrap a function and print out a message of how long it took (inspired by similar @timeit decorators in Python). #[derive(FromDeriveInput, Clone)] // We tell darling that we're looking for arguments // that are defined using the `custom_model` attribute, and // that we May 25, 2019 · Hello, Right now, I have this hypothetical case (ignore the main function). Both zip!(Circle, 52, 32) or zip!(Circle, 52, 32, 5, 100) would present issues, but a macro like this would be a very flexible way to push values onto a new instance of any struct without so much boilerplate. A procedural macro takes proc_macro::TokenStream and produces the same type, but quote gives you a proc_macro2::TokenStream (this is the reason for the into()). A More Complex Example: Argument-based Macros. In the following example, surrounding the matcher with $(),+ will match one or more expression, separated by commas. Hello, I'm trying to make a macro, Feb 3, 2021 · The third arm calls the add macro again with the rest of the arguments; The macro arguments don’t need to be comma-separated. client settings, or Jul 8, 2024 · I'm writing a convenience macro that calls a function which has a few required arguments. Macros are expanded into Rust code during compilation, and can take a variable number of arguments. They are distinguished by a ! at the end. May 5, 2022 · I would like to call macros with a single multi-line string argument, formatted like so: css!(r" background: grey; color: white; "); However, Rustfmt insists on putting the string literal on its own line, which is ugly and takes up more space: May 11, 2024 · However, since the macro now walks down the invocation one argument at a time, you do not need to consider all possible argument orders. You will have to use traits to describe every operation you want to perform, with exact inputs and outputs. Provide details and share your research! But avoid …. Today I thought it would be a nice exercise to learn how to write macro_rules! macros generate those tests Dec 24, 2019 · I am trying to create a macro that fills first elements of a vector with a fixed size. (macro_derive, macro_main) We will create macro what take function signature and generate the callable function. Apr 22, 2019 · The Rust Programming Language Forum Yeah, I'm hoping for a way to call the macro with only required arguments and no trailing commas, though: example!(a, b); Mar 8, 2022 · This topic was automatically closed 90 days after the last reply. Rust syn crate provides parser function. Usage of wildcards for multiple files will group them under a single temporary crate for which dependencies will be built a single time. I added the seq_macro crate to generate the repeated #[test_case]'s. One possibility would be to have the prepare! macro in the regular library, a compiler plugin that also does verification in a separate library, with the verification code shared between the two in a third library. Inspired by Chris Morgan's StackOverflow post and originally documented in this answer, this macro works by dynamically generating a new macro which, in turn, generates separate tests for each test case passed to the generated macro. Jan 27, 2022 · Since @ranfdev's answer is not currently compiling, I've fixed & simpified & extended it to support multiple types -- and it now runs in Rust stable: Apr 24, 2024 · // custom_model. The below macro gets most of the way there: macro Nov 17, 2015 · Might Rust's recursive macro be able to handle this? Macro to count (character) arguments. Now, I want to make a function called "run" or something that takes a variable number of arguments, each of a different type (the type of arguments or number of arguments is variable, however, the the type of each argument is known to implement the trait "Stuff"). Mar 28, 2018 · I am hoping to write a Rust macro which forwards its entire argument to a second macro — even when that argument contains exciting parenthesization. With generics you're going to face these problems: Rust doesn't have variable number of function arguments, so you'll have to use tuples as the input. Unlike functions, macros Macros. Rust Playground link. macro invocation | = note: multiple `impl`s satisfying `_: AsRef<OsStr A place for all things related to the Rust programming language—an open-source systems language that emphasizes performance, reliability, and productivity. Nov 25, 2022 · The only way I found was to cheat a little by using a token tree as one of the arguments like this: macro_rules! test { // secondary invocation with a `[]` delimited list of parameters // as the first arguments and a single second argument. Possible to apply constraints on identifiers passed into a macro? 4. Mar 31, 2021 · Calling functions with different numbers of arguments in Rust macros. Rust macro to format arguments over multiple formats. 3: 623: January 12, 2023 Replacing Macros. So I ended up writing the same test and the same bench many times, one for each version of the function. Attribute Macros. Right now, it works for types without generic parameters, but I'm not sure how to add the type parameters to the impl keyword. I don't need lifetime bounds to work, only trait bounds, but it's still proving pretty tricky. You can only do this using recursion. Feb 16, 2017 · Rust doesn't support overloaded functions/methods. Then I tried reading the actual reference which I feel that got me a few steps further but I still couldn't get it right. Also note that the semicolon is optional on the last case. A | B. Jan 8, 2016 · The workaround to that is to move most of the code in the macro to a method that the macro calls and just have the macro deal with parameter deconstruction and passing to parameters that the method that the macro calls and have the asserts in the method that the macro calls. However that doesn't mean you have. 14. Each macro by example has a name, and one or more rules. rust-analyzer version: 2023-11-06 rustc version: 1. From the reference: A macro invocation expands a macro at compile time and replaces the invocation with the result of the macro. So you can either include comma in the expansion, or add a single case in the macro: All the argument parsing libraries out there (to include clap) have their own strengths and weaknesses. Using a macro Apr 24, 2018 · StructOpt makes the distinction that a Vec<T> will always map to multiple arguments: Vec<T: FromStr> list of options or the other positional arguments. help. Modified 2 years, Parsing Attribute Macro Arguments in Rust. How can I achieve that the arguments are passed down correctly? Feb 11, 2023 · This is the next step in creating macros in Rust. xxtqrpn cclusqea xirtb ccaor nshgzgmt ltjxviu alxtstuj kdkn osm rdcorc idk mlr crvg fpxa ewebw