The Magical Bookstore

One of the joys in life is walking into a bookstore, after being away from bookstores for a good amount of time. I can’t quite say why it is so nice, but I have always felt this way. Recently, I came across an interesting book that made me think about this puzzle. The only thing I can remember about the book is its title. I don’t even remember seeing the book – perhaps I saw it as an online recommendation or reference at the bottom of an article. But it has stuck with me, in a nagging and profound sort of subtle that has me thinking there really is something magic there.

Cow Books in Naka-Meguro, Tokyo

Cow Books in Naka-Meguro, Tokyo


The title of the book is 「なぜ本屋さんに行くとアイデアが生まれるなのか?」(Why is it when you go to a bookstore, ideas are born?). I don’t plan on reading it, at least not for a while. I sort of like the mystic that it provides the bookstore, and the unanswered prompt it gives me for understanding the true values of my own consumerism. That is to say, while there is certainly some connection between books and new ideas, the author clearly asks about bookstores and not other places where you can get free books, such as a friend’s house or a public library.

This makes me recall my first two-year stay in Tokyo, just after I had graduated from college. I integrated where I wanted to, but at the end of the day the nuanced stresses of culture shock led me to foster what I believe is a queer consumerism designed to help keep me grounded in a somewhat foreign land. I would go to Jimbocho, which is the famous book’s quarter and visit many shops on a regular basis. I would search for first editions of classic literature, such as Joyce or Hemmingway. I was a student working a part-time job to fund my entire stay, so I would usually just look at the dusty old tomes through glass and protective plastic, but sometimes I would buy one at a premium rate, this being Japan. Somehow it meant something to me that the books were priced so highly. I think I felt like the money was a token of respect that I could offer to dead authors – that the price valued the book more than normal.

Christopher Alexander’s best known book is still a rare find at bookstores (amazon link)

If I were to visit Japan and go back to the same bookstores today, I would be able to buy many more books than I could have before. This buying power somehow reduces the experience, and my 25-year old self wouldn’t have liked that. Although I don’t have the desire to buy many first editions nowadays, I can still understand what I was doing then. Price labels and and implicit value (positioning and presentation) are such an important part of walking into a bookstore. This is just one part of why bookstores are special places.

Last week, I walked into Pegasus Books on Solano Ave in Albany (California). I was elated to find the architect Christopher Alexander’s The Nature of Order and The Process of Life. His books are always very expensive, even used, perhaps because they are rarer. It is sort of my automatic action to search for Alexander’s books every time I enter a used bookstore. I plan to write more about his Pattern Language, and A Synthesis of Form later. But for now, I will just mention with amazon links that these books were very influential architecture books from the 70s that mesh well into programming practice, and have played a role in influencing the Gang of Four’s Design Patterns.

2014 projects

my barebones background app

my background noise app

It’s been a while since I posted an actual project I’m working on. Since I started working full time for Apportable, I’ll admit there is less time to work on projects, but that’s really no excuse. In addition, as the new year merits such reflection, I’ve been thinking about why I didn’t ship anything last year.

Then I realized, I *technically* shiped something. I shipped my children’s note teaching app (that was already on iOS) on google play using the Apportable framework. Apportable lets you compile your objective-C iOS project to android and run natively. I thought it was lies and insane when I first heard about it; now I can confirm that it is simply black magic. Anyway, I’m usually working on other company’s apps, and improving the Apportable platform where it is is not perfect, so this was a nice way to hit two birds with one stone.

I also started on a binaural beats app, and got a quick prototype, but it didn’t seem as useful or original enough to publish without specific controls, so I’m still working on that. Instead, I put my efforts into a ‘background noise’ app. I started on this because I wanted to be able to drown out the sounds of the 580 and BART that my midcentury apartment building windows are not rude enough to prevent passage into my bedroom. It’s made me remember how much I love the sample synthesis for-loop in an audio callback. (I want to post more on various synthesis techniques in the future). So far the app only has three background noises – rain, waves, and crossfaded white noise. To stay productive, I might just release it as such and develop further as my interest stays with it. To the right is a screenshot of the minimal gl/coregraphics based rendering to accompany the background noise. I’ll try and do a live coding screencast just to get some of it on the screen again.

With the full time job, I can work on all those financially-worthless-but-fun ideas that are musing around in my head that were out of the question when I was doing the solo contract-dev shop. Just to be clear, I am posting this so that I will feel embarrassed if I don’t take advantage of that freedom when I come back and check on this blog.

i used to be a programmer


archy_cover
archy_rats2


Yesterday I was at Owl & Company over on Piedmont Ave in Oakland and came across an interesting read by complete chance. It is a book of poetry and narrative of archy, who was a roach in 1920, and before that, a free verse poet. Archy hops from key to key on a typewriter leaving notes for his human ‘boss’ who owns the typewritter and ‘provides’ him with food in the garbage can. It is a real treat, and because of the whitespace, a real short treat at that. I finished it within a couple hours. The curious thing was that soon after reading this I found an untitled document open on TextEdit that I do not recall having anything to do with. I’m keeping it here so that I can document it.


i used to be a programmer
but now i am just a roach that had my soul transmigrated from
a programmer after i died
why a roach you ask well if you must know
it is for my programmer sins like
using so much indirection and so many underscores
oh the irony
i can t even press the shift key being a roach
can t even make an underscore much less
left parenthesis right parenthesis

the funny thing is
being a roach now
i have many ideas
but can t code any more left parenthesis
i had some ideas while human
they all made money
like the one to drive cars
with mustaches or umlauts
can t remember same thing really
they all take thirty percent right parenthesis

when you die and turn into a roach
they give you all your money
it carries over so to say
but as a roach it is hard to pick up
a dollar bill and
they don t make credit cards for us
but now i have no rent to worry about
i live in a lovely victorian
and the food is good as ever

now i have time to think
come up with some real good ones
but since money doesn t mean anything now
i think of programs to make abstract art
i described it to the venture capitalist
he said people don t want roach art apps
they hate things that are ugly and free
or maybe just things that are free that are made by a roach
i told him i don t need money
he said why dont you need money
i said i m a roach
he said lol i should have known
i am hiring a taskrabbit to step on you
and another to save you to make it a fair game
because they call me an angel investor
and i want to disrupt the world
anyway i decided to leave then

only a few problems for roaches
there is a programmer rat here named steve
code reviewing my text
bad indentation he says
its not even code i say
he says you got that right
what a jerk

Untitled

Here’s my .emacs file in all its unedited glory. May it be a light in your time of google searching or a darkness in your time of trying to understand how to configure emacs.

It’s also in a gist.

It’s a franken.emacs from lots of sources on the net. I’ve forgot them all, but almost none of this functionality originated with me and thus you should give your thanks to the anonymous internet. I wanted to document it for a while because it’s helpful when I switch to a new computer. It’s so messy that I put off documenting it. I’ve decided to share it anyways.
Features are

  • ctrl-x ctrl-o to switch between a .m, .mm, .c, .cpp file to corresponding .h file if it is nearby
  • ctrl-arrow to switch between multiple buffers/windows that you split horizontally or vertically (e.g. with ‘ctrl-x ctrl-3’
  • auto reverts when file changes on disk (e.g. when you git checkout) – note this can be a little dangerous, but I believe it doesn’t do this if you have local modifications
  • copy and paste works with os-x clipboard and vice-versa with your yank/copy/kill ring
  • other stuff

Namespacing a framework in objective-c, @compatibility_alias, and #defines

Shakespeare said something about roses and names smelling nice, but if you’re Outkast you know that sometimes, roses really smell like poo. Additionally, if you’re a programmer, you sometimes need to get another set of better spelling roses to set the world right. Far-fetched metaphors aside, namespacing issues come up less than I would expect. For one, most people know better than to call their classes ‘Object’, and everyone has their own novel solutions to the problem – be it prefixing every class with their initials or a swear word. This week I came across a project that required two implementations of the same framework to be present in the same iOS app. The frameworks had the same, or very similar headers, but the implementations were quite different. The use case in question was for migrating data from one implementation of the framework to another. Objective-C doesn’t have the namespace keyword magic that would make this problem a little faster.

My thought process evolved like this:

  1. My first thought was to rename everything in the old framework by adding a new ‘OLD’ prefix. However, this is quite a lot of work, depending on the size of the framework, and it can be tricky to come up with the right sed command that does everything you wanted.
  2. My next thought was to use #defines for everything I wanted to namespace in the headers only. However, this poses some serious problems for class naming conventions, even if you only conditionally define it within the framework compilation unit. Consider a class called ‘MyClass’. You might have MyClassDelegate, eTargetTypeMyClass, and even other classes with the same prefix or suffix, like MyClassManager or ComplicatedMyClass. #defines might or might not expand in the way you want here – but you can see the risk: it’s easy to end up with half of the file containing ComplicatedOLDMyClass in one compilation unit and OLDComplicatedMyClass in the other.
  3. 3. I found out about @compatibility_alias, which solves the problems with #2 for classes (and nothing else). However, this actually solved most of my problems and was fairly compatible with doing non-class namespacing as mentioned in 2.
  4. @interface OLDMyClass
    ...
    @end
    
    @protocol OLDMyProtocol
    @end
    
    #ifdef COMPILING_MYCLASS
    @compatibility_alias MyClass OLDMyClass; // this tricks the MyClass.m file to use the OLDMyClass interface
    #define MyProtocol OLDMyProtocol
    #endif
    

Limitations of @compatibility_alias:

  1. You can only use it with a real class to an aliased class. You can use it before the real class is declared (but the compiler will emit a warning). If the alias class is already declared, it will cause an error.
  2. You can only use it once per compilation unit for a given alias (you can’t use it liberally like you can with forward declares).
  3. You cannot use it with protocols, typdefs, enums, or anything besides an objective-c class.
  4. All @class MyClass forward decl’s will need to either be swapped out for an #import “MyClass.h” or changing the forward decl to @class OLDMyClass and all occurrances in the header to OLDMyClass.

So how do you namespace the protocols, typedefs, and enums? You could rename everything in the .h and .m files, but it is a lot less work to just ‘#define originalprotocol OLDoriginalprotocol’ and declare OLDProtocol in the header.

You can then #ifdef the #defines and @compatibility_alias’s on the condition that you are compiling the framework itself. This trick is similar to exporting only certain symbols when building a library, and allows for the framework’s implementation (.m files) to be remain almost entirely unchanged (using the ‘originalclass’ form), and when compiling the app, the app only sees the OLD_originalclass form, and also the #defines won’t be able to accidentally expand strings that it happens to match.

I ended up using a sed command only to change the #import to #import.

I did the above for the older version of the framework, and left the newer one unchanged. This allows them to both be used simultaneously. There are other tricks you might be able to do like dynamic loading, but if you need classes from both at the same time, this is probably the way to go.

For reference, here’s a file that I used to test the edge cases. You can compile with ‘clang -framework Foundation compatibility_alias_test.m’, or see the errors caused by wrong usage with ‘clang -DWONT_COMPILE -framework Foundation compatibility_alias_test.m’ :

#include <Foundation/Foundation.h>
#include <stdio.h>

// 1.Only classes work with @compatibility_alias:
// 2. Protocols, typedef, enums and other things are out.
// 3. You might be able to use a #define with #undef for those
// 3.1. If that would interfere with the original namespace you are colliding with,
//      you might try conditionally defining it where it is needed, probably similar
//      to exporting only some symbols when building a lib (if just including headers it would be hidden)

#ifdef WONT_COMPILE
// forward declare of aliased name conflicts with alias
@class SpecificClass; // error: conflicting types for alias 'SpecificClass'
#endif

@protocol NonColiding_BeerHolder
@property (nonatomic, assign) int beers;
@end
#ifdef WONT_COMPILE
@compatibility_alias BeerHolder NonColiding_BeerHolder; // warning: cannot find interface declaration for 'NonColiding_BeerHolder'
// also, later: error: cannot find protocol declaration for 'BeerHolder'
#else
#define BeerHolder NonColiding_BeerHolder
#endif

@interface NonColiding_SpecificClass : NSObject <BeerHolder>
@property (nonatomic, assign) int beers;
@end

@implementation NonColiding_SpecificClass
- (id)initWithBeers:(int)beers
{
    if ((self = [super init])) {
        self.beers = beers;
    }
    return self;
}
@end

@compatibility_alias SpecificClass NonColiding_SpecificClass;

#ifdef WONT_COMPILE
// you also can't double up on compatibility_alias like you can with forward decls.
@compatibility_alias SpecificClass NonColiding_SpecificClass;
#endif

int main(int argc, const char* argv[])
{
    SpecificClass* bob = [[SpecificClass alloc] initWithBeers:5];
    NSObject<BeerHolder>* bh = bob;

    // sanity
    printf("yo dog i'm bob and i have %d beers.\n", bob.beers);
    printf("yo dog i'm a beer holder and i have %d beers.\n", bh.beers);
    [bob release];
}