[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"me":3,"catalog:en:backend\u002Frs-traits-generics-dispatch":4,"config":274},null,{"field_key":5,"field_name":6,"seniority":7,"topic_key":8,"topic_name":9,"spec_key":7,"spec_name":7,"locale":10,"cell_total":11,"field_total":12,"seniorities":13,"topics":17,"specs":166,"samples":189},"backend","Backend","","rs-traits-generics-dispatch","Rs Traits Generics Dispatch","en",75,3750,[14,15,16],"junior","mid","senior",[18,21,24,27,30,33,36,39,42,45,48,51,54,57,60,63,66,69,72,75,78,81,84,87,90,93,96,99,102,105,108,111,114,117,120,123,126,129,132,135,138,141,144,147,150,153,156,159,160,163],{"key":19,"name":20,"count":11},"api-design","API Design",{"key":22,"name":23,"count":11},"caching","Caching",{"key":25,"name":26,"count":11},"concurrency","Concurrency",{"key":28,"name":29,"count":11},"csharp-concurrency-async","Csharp Concurrency Async",{"key":31,"name":32,"count":11},"csharp-exceptions","Csharp 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Lifetimes",{"key":8,"name":9,"count":11},{"key":161,"name":162,"count":11},"security","Security",{"key":164,"name":165,"count":11},"testing","Testing",[167,171,174,177,180,183,186],{"key":168,"name":169,"count":170},"csharp","C#\u002F.NET",450,{"key":172,"name":173,"count":170},"go","Go",{"key":175,"name":176,"count":170},"java","Java",{"key":178,"name":179,"count":170},"nodejs","Node.js",{"key":181,"name":182,"count":170},"php","PHP",{"key":184,"name":185,"count":170},"python","Python",{"key":187,"name":188,"count":170},"rust","Rust",[190,208,222,235,248,261],{"id":191,"topic":9,"difficulty":192,"body":193,"options":194,"correct_key":199,"explanation":207},"01a0608e-d333-7b1f-b024-ddfec7b30057",2,"```rust\nuse std::fmt::Display;\n\nfn label(flag: bool) -> impl Display {\n    if flag { 1 } else { \"one\" }\n}\n\nfn main() {\n    println!(\"{}\", label(true));\n}\n```\nWhat happens when this is compiled?",[195,198,201,204],{"key":196,"text":197},"a","It compiles and prints `1`; each branch is checked against `Display` on its own.",{"key":199,"text":200},"b","E0308: the `if` and `else` branches have incompatible types for the hidden type.",{"key":202,"text":203},"c","E0277: `&str` does not implement `Display`, so only the `1` branch is valid.",{"key":205,"text":206},"d","It compiles and prints `one`; the last expression fixes the concrete type.","`impl Trait` in return position is an opaque alias for a single concrete type chosen by the function body. Here one branch yields `i32` and the other `&str`, so the compiler reports E0308 (`if` and `else` have incompatible types). Both types implement `Display`, so E0277 is not the issue. To return different types behind the same interface you need `Box\u003Cdyn Display>` and box each branch.",{"id":209,"topic":9,"difficulty":210,"body":211,"options":212,"correct_key":205,"explanation":221},"01a0608e-d334-77bf-a61f-491ef12d8b2e",1,"```rust\nuse std::fmt::Display;\n\nfn show\u003CT: Display>(t: T) -> String {\n    format!(\"\u003C{}>\", t)\n}\n\nfn main() {\n    println!(\"{}\", show(vec![1, 2]));\n}\n```\nWhat is the result?",[213,215,217,219],{"key":196,"text":214},"It prints `\u003C[1, 2]>` using `Vec`'s `Debug` output.",{"key":199,"text":216},"E0308: `Vec\u003Ci32>` is not the `T` the function expects.",{"key":202,"text":218},"E0282: `T` cannot be inferred from a `vec!` literal.",{"key":205,"text":220},"E0277: `Vec\u003C{integer}>` doesn't implement `Display`.","Generic bounds are checked at the call site. `Vec\u003CT>` implements `Debug` but deliberately not `Display` (there is no canonical human-readable form), so `show(vec![1, 2])` violates `T: Display` and rustc reports E0277. `T` itself is inferred fine (no E0282), and there is no type mismatch (no E0308) — the bound is what fails.",{"id":223,"topic":9,"difficulty":192,"body":224,"options":225,"correct_key":196,"explanation":234},"01a0608e-d335-7b8c-97d6-c3ec7f58f457","```rust\ntrait Task {\n    fn run(&self);\n}\n\nfn execute(t: dyn Task) {\n    t.run();\n}\n```\nWhy does this not compile?",[226,228,230,232],{"key":196,"text":227},"E0277: `dyn Task` has no compile-time size, so it must sit behind `&` or `Box`.",{"key":199,"text":229},"It compiles; `t.run()` goes through the vtable like any trait-object call.",{"key":202,"text":231},"E0038: `Task` is not dyn compatible because `run` takes `&self` rather than `self`.",{"key":205,"text":233},"E0308: a trait cannot be a parameter type, only a bound such as `T: Task`.","A trait object `dyn Task` is unsized: different implementors have different sizes, so a by-value parameter has no fixed stack size. Function parameters must be `Sized`, hence E0277. Trait objects are always used behind a pointer (`&dyn Task`, `Box\u003Cdyn Task>`, `Rc\u003Cdyn Task>`). `Task` itself is perfectly dyn compatible — the `&self` receiver is exactly what trait objects need.",{"id":236,"topic":9,"difficulty":210,"body":237,"options":238,"correct_key":202,"explanation":247},"01a0608e-d337-71c7-9dba-442f2109d122","```rust\ntrait Greet {\n    fn name(&self) -> String;\n    fn hello(&self) -> String {\n        format!(\"Hello, {}!\", self.name())\n    }\n}\nstruct A;\nimpl Greet for A {\n    fn name(&self) -> String { \"A\".into() }\n}\nstruct B;\nimpl Greet for B {\n    fn name(&self) -> String { \"B\".into() }\n    fn hello(&self) -> String { \"Hi B\".into() }\n}\n\nfn main() {\n    println!(\"{} | {}\", A.hello(), B.hello());\n}\n```\nWhat is printed?",[239,241,243,245],{"key":196,"text":240},"`Hello, A! | Hello, B!`",{"key":199,"text":242},"E0407: `B` cannot override `hello`.",{"key":202,"text":244},"`Hello, A! | Hi B`",{"key":205,"text":246},"E0046: `A` is missing `hello`.","A trait method with a body is a default method: implementors may omit it (as `A` does) or override it (as `B` does). The default `hello` calls the required `name` through `self`, so `A.hello()` yields `Hello, A!`, while `B`'s override returns `Hi B`. Nothing forces `A` to implement `hello`, and nothing forbids `B` from replacing it.",{"id":249,"topic":9,"difficulty":210,"body":250,"options":251,"correct_key":196,"explanation":260},"01a0608e-d339-7d3b-af14-5a5b490edcd8","```rust\nstruct Point { x: i32, y: i32 }\n\nfn main() {\n    let p = Point { x: 1, y: 2 };\n    println!(\"{:?}\", p);\n}\n```\nWhat does the compiler say?",[252,254,256,258],{"key":196,"text":253},"E0277: `Point` doesn't implement `Debug`; `#[derive(Debug)]` fixes it.",{"key":199,"text":255},"It prints `Point { x: 1, y: 2 }`; `{:?}` works on any struct.",{"key":202,"text":257},"E0599: no method `fmt` for `Point`; call `p.fmt()` explicitly.",{"key":205,"text":259},"E0308: `{:?}` expects a `String`, so `p.to_string()` is required first.","`{:?}` requires the `Debug` trait, and user-defined types get no formatting traits automatically. rustc reports E0277 (`Point` doesn't implement `Debug`) and suggests `#[derive(Debug)]`, which generates an impl printing `Point { x: 1, y: 2 }`. Field visibility plays no role, and `to_string()` would need `Display`, a different trait.",{"id":262,"topic":9,"difficulty":192,"body":263,"options":264,"correct_key":205,"explanation":273},"01a0608e-d33c-70e9-a5a7-116156e3aa4d","```rust\nmod shapes {\n    pub trait Area { fn area(&self) -> f64; }\n    pub struct Sq(pub f64);\n    impl Area for Sq {\n        fn area(&self) -> f64 { self.0 * self.0 }\n    }\n}\n\nfn main() {\n    let s = shapes::Sq(2.0);\n    println!(\"{}\", s.area());\n}\n```\nWhat happens?",[265,267,269,271],{"key":196,"text":266},"It prints `4`; the impl lives next to `Sq`, so the method is always visible on the type.",{"key":199,"text":268},"E0603: `Area` is private to `shapes` and needs `pub use` before it can be called.",{"key":202,"text":270},"E0277: `Sq` does not implement `Area` outside the `shapes` module.",{"key":205,"text":272},"E0599: no method `area` found for `Sq`; the trait must be brought into scope with `use`.","Trait methods are only callable when the trait is in scope. The impl exists and `Area` is `pub`, but `main` has not imported it, so method resolution cannot see `area` and rustc reports E0599, adding the hint that items from traits can only be used if the trait is in scope. A single `use shapes::Area;` makes it print `4`. This is also why `use std::io::Write;` is needed before calling `write_all` on a file.",{"fields":275,"seniorities":495,"interview_shapes":496,"locales":503,"oauth":505,"question_count":508,"coach_enabled":509,"jd_match_enabled":509},[276,288,308,326,350,363,382,401,421,440,455,477],{"key":5,"name_tr":6,"name_en":6,"sort":210,"specializations":277},[278,281,282,283,284,285,286,287],{"key":279,"name":280,"field":5},"general","Genel",{"key":172,"name":173,"field":5},{"key":184,"name":185,"field":5},{"key":175,"name":176,"field":5},{"key":168,"name":169,"field":5},{"key":178,"name":179,"field":5},{"key":181,"name":182,"field":5},{"key":187,"name":188,"field":5},{"key":289,"name_tr":290,"name_en":290,"sort":192,"specializations":291},"frontend","Frontend",[292,293,296,299,302,305],{"key":279,"name":280,"field":289},{"key":294,"name":295,"field":289},"javascript","JavaScript",{"key":297,"name":298,"field":289},"typescript","TypeScript",{"key":300,"name":301,"field":289},"react","React",{"key":303,"name":304,"field":289},"vue","Vue",{"key":306,"name":307,"field":289},"angular","Angular",{"key":309,"name_tr":310,"name_en":310,"sort":311,"specializations":312},"fullstack","Fullstack",3,[313,314,315,316,317,318,319,320,321,322,323,324,325],{"key":279,"name":280,"field":309},{"key":172,"name":173,"field":5},{"key":184,"name":185,"field":5},{"key":175,"name":176,"field":5},{"key":168,"name":169,"field":5},{"key":178,"name":179,"field":5},{"key":181,"name":182,"field":5},{"key":187,"name":188,"field":5},{"key":294,"name":295,"field":289},{"key":297,"name":298,"field":289},{"key":300,"name":301,"field":289},{"key":303,"name":304,"field":289},{"key":306,"name":307,"field":289},{"key":327,"name_tr":328,"name_en":328,"sort":329,"specializations":330},"devops-cloud","DevOps \u002F Cloud",4,[331,332,335,338,341,344,347],{"key":279,"name":280,"field":327},{"key":333,"name":334,"field":327},"aws","AWS",{"key":336,"name":337,"field":327},"gcp","GCP",{"key":339,"name":340,"field":327},"azure","Azure",{"key":342,"name":343,"field":327},"kubernetes","Kubernetes",{"key":345,"name":346,"field":327},"terraform","Terraform",{"key":348,"name":349,"field":327},"linux","Linux",{"key":351,"name_tr":352,"name_en":352,"sort":353,"specializations":354},"ai-engineer","AI Engineer",5,[355,356,357,360],{"key":279,"name":280,"field":351},{"key":184,"name":185,"field":351},{"key":358,"name":359,"field":351},"llm-rag","LLM\u002FRAG",{"key":361,"name":362,"field":351},"mlops","MLOps",{"key":364,"name_tr":365,"name_en":366,"sort":367,"specializations":368},"database","Veritabanı","Database",6,[369,370,373,376,379],{"key":279,"name":280,"field":364},{"key":371,"name":372,"field":364},"postgresql","PostgreSQL",{"key":374,"name":375,"field":364},"mysql","MySQL",{"key":377,"name":378,"field":364},"mongodb","MongoDB",{"key":380,"name":381,"field":364},"redis","Redis",{"key":383,"name_tr":384,"name_en":385,"sort":386,"specializations":387},"mobile","Mobil","Mobile",7,[388,389,392,395,398],{"key":279,"name":280,"field":383},{"key":390,"name":391,"field":383},"ios-swift","iOS (Swift)",{"key":393,"name":394,"field":383},"android-kotlin","Android (Kotlin)",{"key":396,"name":397,"field":383},"flutter","Flutter",{"key":399,"name":400,"field":383},"react-native","React 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QA",{"key":441,"name_tr":442,"name_en":442,"sort":443,"specializations":444},"data-engineer","Data Engineer",10,[445,446,449,452],{"key":279,"name":280,"field":441},{"key":447,"name":448,"field":441},"pipelines-etl","Pipelines \u002F ETL",{"key":450,"name":451,"field":441},"streaming","Streaming",{"key":453,"name":454,"field":441},"warehousing","Warehousing",{"key":456,"name_tr":457,"name_en":458,"sort":459,"specializations":460},"game-dev","Oyun Geliştirme","Game Development",11,[461,462,465,468,471,474],{"key":279,"name":280,"field":456},{"key":463,"name":464,"field":456},"unity-csharp","Unity (C#)",{"key":466,"name":467,"field":456},"unreal-cpp","Unreal (C++)",{"key":469,"name":470,"field":456},"gameplay","Gameplay",{"key":472,"name":473,"field":456},"graphics-rendering","Graphics \u002F Rendering",{"key":475,"name":476,"field":456},"multiplayer-netcode","Multiplayer \u002F Netcode",{"key":478,"name_tr":479,"name_en":479,"sort":480,"specializations":481},"ml-engineer","ML 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