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>There's a reason why computer science professors explain concepts at a high or abstract level and don't jump into implementation to help students understand th

>There's a reason why computer science professors explain concepts at a high or abstract level and don't jump into implementation to help students understand them. It's because they're trying to teach something to people who don't have anything to build on. Later in their education that'll be different. At the school I attended Object Oriented Programming class had Computer Organization as a pre-req and the teacher would often tangent into generated assembly to help students understand what was happening. Regardless of whether I agree with your thoughts about the ideal approach to understanding the concepts vs implementation, I live in the status quo where - sooner or later - a C++ programmer is going to encounter a situation where they need to know what a vtable is.

WalterBright 5y ago
I did not understand what virtual functions were at all until I examined the output of cfront. Oh, it's just a table of function pointers.
- donkeybeer 5y ago
  Sometimes textbook descriptions are just needlessly obtuse. I have noticed that there are some concepts which I already understood but if I were first introduced to them via the textbook, I would have been hopelessly confused. I wasn't confused only because I recognized this as something I already knew.
- CRConrad 5y ago
  You must have just had the bad luck to have read the most appallingly stupid books. I think you might be even a little older than I, and I got into the game late-ish; those C++ manuals or specs you read were probably from the 1970s or 80s? By the time I learned (imperative- and inheritance-based[1]) OOP from the Delphi manuals in the late nineties the virtual method table was explicitly mentioned and explained, along with stuff like "since all objects are allocated on the heap, all object references are implicitly pointers; therefore, Borland Object Pascal syntax omits the pointer dereferencing markers on object variable names" (which you also mention about C above). I'm fairly certain this gave the reader a pretty good grasp of how objects work in Delphi, but I still know nothing about what machine language the compiler generates for them. It's not the idea of top-down learning from abstractions that's wrong, it's being given a shitty presentation -- more of an obfuscation, it seems -- to learn about the abstractions from that is the problem. ___ [1]: So yeah, that whole Smalltalk-ish "messaging paradigm" still feels like mumbo-jumbo to me... Perhaps because it's even older than C++, so there never were any sensible Borland manuals for it.

WalterBright 5y ago

I did not understand what virtual functions were at all until I examined the output of cfront. Oh, it's just a table of function pointers.

donkeybeer 5y ago
Sometimes textbook descriptions are just needlessly obtuse. I have noticed that there are some concepts which I already understood but if I were first introduced to them via the textbook, I would have been hopelessly confused. I wasn't confused only because I recognized this as something I already knew.
CRConrad 5y ago
You must have just had the bad luck to have read the most appallingly stupid books. I think you might be even a little older than I, and I got into the game late-ish; those C++ manuals or specs you read were probably from the 1970s or 80s? By the time I learned (imperative- and inheritance-based[1]) OOP from the Delphi manuals in the late nineties the virtual method table was explicitly mentioned and explained, along with stuff like "since all objects are allocated on the heap, all object references are implicitly pointers; therefore, Borland Object Pascal syntax omits the pointer dereferencing markers on object variable names" (which you also mention about C above). I'm fairly certain this gave the reader a pretty good grasp of how objects work in Delphi, but I still know nothing about what machine language the compiler generates for them. It's not the idea of top-down learning from abstractions that's wrong, it's being given a shitty presentation -- more of an obfuscation, it seems -- to learn about the abstractions from that is the problem. ___ [1]: So yeah, that whole Smalltalk-ish "messaging paradigm" still feels like mumbo-jumbo to me... Perhaps because it's even older than C++, so there never were any sensible Borland manuals for it.