Bjarne Stroustrup: C++ | Lex Fridman Podcast #48
TLDRBjarne Stroustrup, creator of C++, discusses the origins and evolution of the programming language. He explores key concepts like abstraction, efficiency, and reliability that have shaped C++ over 40+ years into one of the most widely used languages. Stroustrup explains pivotal milestones like object-oriented programming andTEMPLATES as well as the ISO standardization process. He shares perspectives on C++'s role in critical systems and his vision for concepts that establish firm requirements between GENERIC components. Ultimately, Stroustrup reflects on C++’s ongoing impact and his drive to keep improving it.
Takeaways
- 😀 C++ was designed to allow programmers to efficiently access hardware capabilities through abstractions.
- 👨💻 Stroustrup took concepts like classes and virtual functions from Simula and aimed to implement them efficiently in C++.
- 🔧 The core mechanisms that define C++ objects are constructors, which initialize them, and destructors, which free resources.
- 🚘 Reliability and constraints were key considerations in C++ to support systems like fuel injection control.
- 🌎 Multiple C++ implementations were assumed from the start to suit diverse hardware.
- 🏛 The first C++ standard in 1998 took 8 years; later ones took longer due to more ambition.
- 📜 Concepts for templates provide compile-time checking of template arguments, crucial for performance.
- ⏱ The zero-overhead principle aims for abstractions to have minimal cost compared to lower-level code.
- 💡 Modern optimizations mean simplicity and clean expression now enable the best C++ performance.
- 🤝 Despite differences, programming languages share philosophical principles about resources, types etc.
Q & A
What was the first program Bjarne Stroustrup ever wrote?
-The first program Bjarne Stroustrup ever wrote was in Algol 60 during his second year of university. It calculated the shape of super ellipses and connected points on the perimeter, creating star patterns using a pen plotter.
What drew Stroustrup to C++ and low-level programming languages?
-Stroustrup was drawn to C++ and low-level languages because of their simplicity, efficiency, and ability to give the programmer control over hardware resources and memory. He also liked being able to build his own types and abstraction mechanisms.
How did object-oriented programming in C++ achieve high performance?
-C++ achieved high performance object-oriented programming through the use of simple, efficient implementations like virtual function tables and jump tables for polymorphism. This kept the overhead low compared to alternatives.
What is the zero overhead principle in C++?
-The zero overhead principle states that C++ abstractions should have minimal or no performance cost compared to writing equivalent lower-level code directly. The goal is for programmers to use abstractions without losing performance.
What are some key milestones in the evolution of C++ features?
-Some key milestones include: constructors/destructors for resource management in 1979, control of copying/moving to manage object lifetimes, templates and generics for code reuse, standard library and STL in 1998, multi-threading support in 2011, concepts for template constraints in 2020.
How is the C++ language standardized?
-C++ is standardized through an open ISO process of international committees that meet regularly to discuss proposals and hold votes. Consensus of national bodies is required to publish a new standard every 3 years now.
What C++ feature is Bjarne most proud of?
-Bjarne is most proud of constructors and destructors in C++. He sees this as central to enabling clean resource management without needing garbage collection for performance.
How does C++ achieve reliability and efficiency?
-C++ achieves reliability through features like strong typing and RAII resource management. It achieves efficiency through zero-overhead abstractions, compile-time evaluation, and producing optimized machine code.
Why can't fuzzy AI systems replace C++?
-Fuzzy unreliable AI systems cannot replace C++ in critical infrastructure. C++ offers precision, efficiency, reliability, and predictability needed for systems like vehicles, reactors, and rockets.
What motivates Bjarne to continue evolving C++?
-Seeing C++ help build cool technology by talented people motivates Bjarne. Advancing C++ improves what millions of developers can build across domains like aerospace, automotive, etc.
Outlines
😀 Bjorn's First Program
Bjorn wrote his first program in his second year of university - it calculated and displayed star patterns by connecting perimeter points of super ellipses using a pen plotter. The first programming language he learned was Algol 60.
👨💻 Choosing His First Love - Simplicity and Efficiency
Bjorn did not fall in love with early languages like Algol 60, Fortran, and Pascal. He discovered Simplicity and became fascinated by its efficiency and ability to directly express ideas in code. This led him to value performance and reliability in languages.
😍 Discovering Simula - Birth of OOP
Bjorn learned object-oriented programming concepts like inheritance and runtime polymorphism from Simula's inventors - Ole-Johan Dahl and Kristen Nygaard. Simula allowed flexible creation of new types to fit specific domains and applications.
🌎 History of Programming Languages
Major milestones included: Fortran - first portable language, COBOL - for business, Algol 60 - introduced concepts like scope and translation phases, Simula - invented OOP concepts like inheritance and runtime polymorphism. Simplicity and efficiency were Bjorn's focus.
⚡️ Zero Overhead Principle
A key principle Bjorn followed when designing C++ features was zero overhead - abstractions should not impose overhead compared to hand written lower-level code. This enabled high performance despite high-level abstractions.
👶 Birth of C++
Bjorn designed C++ to enable control over hardware through abstractions for managing complexity. It combines: 1) Low-level memory manipulation like C 2) User defined types/classes for abstraction 3) Object oriented and generic programming concepts.
💎 Constructors and Destructors
The language feature Bjorn considers most beautiful is constructors establishing context for objects and destructors automatically cleaning up resources. This is key to efficiency, performance and avoiding garbage collection in C++.
🏭 Standardizing C++
Standardization of C++ started in 1989 to ensure portability across implementations. The open ISO process has participants from many countries meeting thrice annually to discuss and vote on proposals for the evolving standard.
🚀 Optimizing Abstractions
Zero overhead principle guided optimization of abstractions like virtual functions through ideas like jump tables for minimal indirect function call overhead. Templates generate optimized code combining program context.
📈 Faster Compilation and Debugging
Compiler output is optimized rather than readable, so debugging works best with optimizations disabled. Concepts constrain templates for faster compilation. Better static analysis is coming to catch more errors at compile time.
❤️ Bjorn's Favorite Feature
The constructor/destructor pair that controls object lifetime and resource acquisition/release is Bjorn's favorite feature. It enables efficiency and performance without needing garbage collection.
🌐 The Future of C++
Faster release cycles ensure timely delivery of features. Competition among implementations improves quality and conformance. A set of principles guides language evolution towards convergence with other languages in various domains.
Mindmap
Keywords
💡C++
💡abstraction
💡zero overhead principle
💡Simula
💡C
💡constructors/destructors
💡templates
💡ISO standardization
💡C++11/14/17/20
💡principles
Highlights
C++ is focused on fast, stable, robust code that underlies major systems we rely on like YouTube, Google, Facebook, Amazon, etc.
Classes in C++ are user-defined types that should work as efficiently as built-in types like int.
Key C++ features: low-level memory access like C, plus abstraction through classes and generics.
The combination of constructors establishing context and destructors cleaning up is key to C++ performance and minimal overhead vs garbage collection.
Good C++ code simplifies rather than getting clever - often dropping clever bits makes code faster by enabling optimization.
The 0-overhead principle: C++ abstractions should not introduce runtime costs vs hand written lower-level code.
Standardizing C++ through an open ISO process balanced corporate interests and enabled widespread quality implementations.
The C++ standards process shifted from 10 year cycles that allowed undisciplined feature creep to 3 year cycles with more frequent, predictable releases.
Concepts are compile-time predicates that specify requirements on generic parameters to enable stricter checking.
The C++ type system and abstraction mechanisms aim to directly express programmer thinking so code can be maintained and analyzed.
C++ focuses on precision, constraints and minimization of runtime errors for areas like systems programming where reliability is critical.
Fuzzy machine learning techniques are poorly matched to domains like transportation and finance that demand precision and reliability.
No system today is built in one language - different tools with different principles serve different application domain needs.
At a philosophical level, common principles apply across languages - like avoiding resource leaks and respecting type systems.
The C++ language and standard libraries aim to directly express ideal machine code a compiler would generate - enabling performance.
Transcripts
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