Rust for C++ programmers

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Adenilson Cavalcanti BSc MSc

WebKit & Blink committer W3C CSS WG member

Rust for C++ programmers

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Summary

Introduction

The case for Rust

Operators x traits

Templates x generics

Macros x attributes

Threads x tasks

Heap x boxes

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Introduction

The problem: •  There are many C++ programmers •  But few Rust programmers

The solution: Why not explain Rust comparing it with modern C++11?

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C++ x Rust

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Why Rust?

•  It aims to solve some gruesome issues in C/C++.

• Be more expressive for hard tasks. • Safety X performance: have both!

The case for Rust

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C++ example: anything wrong here?

http://doc.rust-lang.org/nightly/intro.html#ownership

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Run on valgrind: warnings

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Using gdb to understand what is happening…

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Address: 0x100103af0

Address

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Change! Now: 0x100103b10

Address

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Ref points to old address!

Compiler warnings won’t catch it:

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Rust to the rescue!

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Rust stops bugs from happening.

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Introduction

• A C++ example is given • A similar Rust program is presented

How it is done

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Introduction

• Get used to Rust syntax • Compare it with a mainstream language

Objective

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C++ operators

• Allows to overload operators (e.g. +, -, (), [], etc)

• Improves code readability and reuse

Use

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C++ operators

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Rust traits

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C++ templates

• Parametric types at compile type

• Improves performance and code reuse

Use

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C++ templates

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Rust generics

//http://doc.rust-lang.org/src/core/home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/libcore/mem.rs.html#270-284 http://en.cppreference.com/w/cpp/utility/move

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C++ macros

• Conditional compilation, performance code, etc

• When possible, use inline functions instead.

Use

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C++ macros

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Rust attributes

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C++ threads

• Parallelism, performance.

• Can get messy pretty fast.

Use

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Rust tasks

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C++ heap

• Memory allocation of objects (i.e. stack has a fixed size).

• Be careful with leaks (smart pointers are your friend).

Use

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C++ heap use

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Rust boxes

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Conclusions •  Rust has equivalent features to modern C++; •  The same programming style won’t work to both languages: you have to code in the right style; •  For smaller tasks, C++ may have more compact code; •  For more complex tasks (i.e. multitask), Rust seems to be more expressive; •  Most importantly: Rust avoids common traps in C++.

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Questions?

Thank you.

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