Fallacies of Doom - JavaZone 18

Fallacies of Doom Lessons learned from porting Doom 3 to
Java

@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?

@blackbeard0x14e

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

@blackbeard0x14e

@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

@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

@blackbeard0x14e

@blackbeard0x14e >>>

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

@blackbeard0x14e @blackbeard0x14e Unsigned primitives

@blackbeard0x14e @blackbeard0x14e Unsigned primitives Microbenchmark alert:

@blackbeard0x14e

@blackbeard0x14e @blackbeard0x14e Immutability; const vs final

@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

@blackbeard0x14e @blackbeard0x14e sizeof( )

@blackbeard0x14e @blackbeard0x14e Enum

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

@blackbeard0x14e

@blackbeard0x14e @blackbeard0x14e Pointers

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

@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 @blackbeard0x14e Death by Macros

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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

@blackbeard0x14e Hungarian Camels

@blackbeard0x14e @blackbeard0x14e Unholy union

@blackbeard0x14e @blackbeard0x14e Unholy union: SDL_events.h

@blackbeard0x14e Unholy union

@blackbeard0x14e @blackbeard0x14e Unholy union

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

@blackbeard0x14e

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

@blackbeard0x14e Default arguments

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

@blackbeard0x14e @blackbeard0x14e Inlining

@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);

@blackbeard0x14e @blackbeard0x14e The memory watcher

@blackbeard0x14e @blackbeard0x14e 5.1.2. Widening Primitive Conversion

@blackbeard0x14e @blackbeard0x14e Pop goes the callstack

@blackbeard0x14e @blackbeard0x14e Floating point operator precedence

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@blackbeard0x14e @blackbeard0x14e Floating point operator precedence

@blackbeard0x14e @blackbeard0x14e Conditional breakpoints

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

@blackbeard0x14e @blackbeard0x14e A backwards compatible story?

@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?

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

@blackbeard0x14e @blackbeard0x14e

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

Fallacies of Doom - JavaZone 18

Fallacies of Doom - JavaZone 18

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