Fallacies of Doom - JavaZone 18

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Fallacies of Doom Lessons learned from porting Doom 3 to Java

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@blackbeard0x14e @blackbeard0x14e Boring intro: history • id Software: Unusual company creating ‘innovative’ games(Rover, Dave, Keen, Wolf3D, Doom, Quake) • Self taught era, efficient coding style(s) ○ Nerd rage anecdote • Djoom3==fun • So why the boring awesome intro?

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@blackbeard0x14e

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@blackbeard0x14e wishlist “ C++ protects against accident, not against fraud. ” Bjarne Stroustrup

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@blackbeard0x14e

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@blackbeard0x14e @blackbeard0x14e Operator overloading cout << ”Total price: “ << price*quantity << endl; c->J1 * c->body1->acceleration + c->J2 * c->body2->acceleration + invStep * (c->c1 + c->c2); c.J1.oMultiply(c.body1.acceleration).oPlus(c.J2.oMultiply(c.body2.acceleration) ).oPlus((c.c1.oPlus(c.c2)).oMultiply(invStep)); [2] https://www.cs.virginia.edu/~evans/cs655/readings/steele.pdf

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@blackbeard0x14e @blackbeard0x14e Operator overloading idMat3 a, b, c, z; z = a + b * c; z = a.oPlus(b).oMultiply(c); z = b.oMultiply(c).oPlus(a);//technically correct z = a.oPlus(b.oMultiply(c));//compiler correct

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@blackbeard0x14e

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@blackbeard0x14e >>>

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@blackbeard0x14e @blackbeard0x14e Unsigned primitives Runtime or compile-time error??

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@blackbeard0x14e @blackbeard0x14e Unsigned primitives

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@blackbeard0x14e @blackbeard0x14e Unsigned primitives Microbenchmark alert:

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@blackbeard0x14e

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@blackbeard0x14e @blackbeard0x14e Immutability; const vs final

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@blackbeard0x14e @blackbeard0x14e Immutability; const vs final • final for variables sucks • final for functions sucks less • final for classes rocks [1] ftp://ftp.idsoftware.com/idstuff/doom3/source/CodeStyleConventions.doc

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@blackbeard0x14e @blackbeard0x14e sizeof( )

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@blackbeard0x14e @blackbeard0x14e sizeof( )

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@blackbeard0x14e @blackbeard0x14e Enum

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@blackbeard0x14e @blackbeard0x14e Enum

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@blackbeard0x14e @blackbeard0x14e Enum

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@blackbeard0x14e @blackbeard0x14e Grandfather inheritance • Super.super.function • Why are equals/hashcode inherited?!

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@blackbeard0x14e

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@blackbeard0x14e @blackbeard0x14e Pointers

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@blackbeard0x14e @blackbeard0x14e Pointers

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@blackbeard0x14e @blackbeard0x14e Pointers

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@blackbeard0x14e @blackbeard0x14e Pointers

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@blackbeard0x14e (thank God we don’t have this…)-list System.out.println( (byte)~(char)-(int)+(long)-1 );

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@blackbeard0x14e @blackbeard0x14e Death by Macros [3] https://blogs.msdn.microsoft.com/oldnewthing/20050106-00/?p=36783 [4] https://youtu.be/4cCeUfzH-No?t=23m

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@blackbeard0x14e

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@blackbeard0x14e @blackbeard0x14e Death by Macros

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@blackbeard0x14e @blackbeard0x14e Death by Macros

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@blackbeard0x14e @blackbeard0x14e Death by Macros

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@blackbeard0x14e

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@blackbeard0x14e @blackbeard0x14e Hungarian Camels [5]https://www.joelonsoftware.com/2005/05/11/making-wrong-code-look-wrong/ [6] https://steve-yegge.blogspot.nl/2006/03/execution-in-kingdom-of-nouns.html

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@blackbeard0x14e Hungarian Camels

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@blackbeard0x14e @blackbeard0x14e Unholy union

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@blackbeard0x14e @blackbeard0x14e Unholy union: SDL_events.h

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@blackbeard0x14e Unholy union

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@blackbeard0x14e @blackbeard0x14e Unholy union

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@blackbeard0x14e nice to have -list “ Object-oriented design is the roman numerals of Computing. ” Rob Pike

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@blackbeard0x14e

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@blackbeard0x14e @blackbeard0x14e Destructor • Deconstructors • Finalize(@deprecated) • Autocloseable++

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@blackbeard0x14e Default arguments

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@blackbeard0x14e @blackbeard0x14e string::insert, string::swap

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@blackbeard0x14e @blackbeard0x14e Inlining

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@blackbeard0x14e weird(tips...tricks...pitfalls) -list Integer a = 42; Integer b = 42; System.out.println(a == b); Integer c = 666; Integer d = 666; System.out.println(c == d); String e = “666”; String f = “666”; String g = new String(“666”); System.out.println(e == f); System.out.println(f == g);

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@blackbeard0x14e @blackbeard0x14e The memory watcher

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@blackbeard0x14e @blackbeard0x14e 5.1.2. Widening Primitive Conversion

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@blackbeard0x14e @blackbeard0x14e Pop goes the callstack

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@blackbeard0x14e @blackbeard0x14e Floating point operator precedence

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@blackbeard0x14e @blackbeard0x14e Floating point operator precedence

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@blackbeard0x14e

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@blackbeard0x14e @blackbeard0x14e Floating point operator precedence

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@blackbeard0x14e @blackbeard0x14e Floating point operator precedence

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@blackbeard0x14e @blackbeard0x14e Conditional breakpoints

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@blackbeard0x14e @blackbeard0x14e Conditional breakpoints •Sloooow(interpretive) Microbenchmark alert:

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@blackbeard0x14e @blackbeard0x14e A backwards compatible story?

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@blackbeard0x14e @blackbeard0x14e A backwards compatible story? •Why is backwards compatibility the default mode of operation? •Why not make it optional with compile/runtime warnings/errors?

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@blackbeard0x14e @blackbeard0x14e Sometimes the bug isn’t in your code...T_T

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@blackbeard0x14e @blackbeard0x14e

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@blackbeard0x14e Questions...while the Demo loads? https://github.com/blackbeard334/djoom3