Skip to main content

Installing Google Go on Mac OS X

I decided to have a go with Google Go since I'm an old fogey C/C++ programmer. Any new innovation in the C/C++ family gets me excited and Google Go has quite a few nice features (garbage collection is really nice to have and channels make me think of all the work I did in CSP).

I decided to go with the 6g compiler since gccgo doesn't have garbage collection implemented yet and hence there's no way to free memory. The only way to get 6g is to mirror its Mercurial repository. So...

Step 1: Install Mercurial

For that I used prebuilt packages from here and got Mercurial 1.4 for Mac OS X 1.5 (no, I haven't upgraded to Snow Leopard yet).

Step 2. Set GOROOT

I just did a quick cd ; mkdir go ; export GOROOT=$HOME/go to get me started.

Step 3. Clone the 6g repository

That was a quick hg clone -r https://go.googlecode.com/hg/ $GOROOT followed by the hard part: compiling it. You need to have gcc, make, bison and ed installed (whcih I do since I do development work on my Mac).

Step 5. Set GOBIN

This points to where the binaries will go, for me that's $HOME/bin since I'll be doing local development using Go. And I updated PATH to include $GOBIN.

Step 4. Compile 6g

You first need to set GOARCH and GOOS. For me that's amd64 for the architecture (the Intel Core 2 Duo in my Macbook Air is a 64-bit processor) and darwin for the OS (since this is a Mac).

$ export GOARCH=amd64
$ export GOOS=darwin

Then you can actually do the compile:

$ cd $GOROOT/src
$ ./all.bash

This does a build and test of 6g and it was very fast to build (although I'm used to building gcc which is a bit of a monster).

Step 5. Write a Hello, World! program

Here's my first little Google Go program (filename: hw.go) just to test the 6g compiler.

package main

import "fmt"

func main() {
fmt.Printf( "Hello, World\n" );
}

To simplify building I made a minimal Makefile:

all: hw
hw: hw.6 ; 6l -o [email protected] $^
%.6: %.go ; 6g $<

And then the magic moment:

$ make
6g hw.go
6l -o hw hw.6
$ ./hw
Hello, World!

And now for a real project... get SQLite to interface to it.

Comments

aaronblohowiak said…
hg clone -r https://go.googlecode.com/hg/ $GOROOT

did not work for me after using macports to install mercurial and setup python26. removing the "-r" made this work.

Popular posts from this blog

Your last name contains invalid characters

My last name is "Graham-Cumming". But here's a typical form response when I enter it:


Does the web site have any idea how rude it is to claim that my last name contains invalid characters? Clearly not. What they actually meant is: our web site will not accept that hyphen in your last name. But do they say that? No, of course not. They decide to shove in my face the claim that there's something wrong with my name.

There's nothing wrong with my name, just as there's nothing wrong with someone whose first name is Jean-Marie, or someone whose last name is O'Reilly.

What is wrong is that way this is being handled. If the system can't cope with non-letters and spaces it needs to say that. How about the following error message:

Our system is unable to process last names that contain non-letters, please replace them with spaces.

Don't blame me for having a last name that your system doesn't like, whose fault is that? Saying "Your last name …

All the symmetrical watch faces (and code to generate them)

If you ever look at pictures of clocks and watches in advertising they are set to roughly 10:10 which is meant to be the most attractive (smiling!) position for the hands. They are actually set to 10:09.14 if the hands are truly symmetrical. CC BY 2.0image by Shinji
I wanted to know what all the possible symmetrical watch faces are and so I wrote some code using Processing. Here's the output (there's one watch face missing, 00:00 or 12:00, because it's very boring):



The key to writing this is to figure out the relationship between the hour and minute hands when the watch face is symmetrical. In an hour the minute hand moves through 360° and the hour hand moves through 30° (12 hours are shown on the watch face and 360/12 = 30).
The core loop inside the program is this:   for (int h = 0; h <= 12; h++) {
    float m = (360-30*float(h))*2/13;
    int s = round(60*(m-floor(m)));
    int col = h%6;
    int row = floor(h/6);
    draw_clock((r+f)*(2*col+1), (r+f)*(row*2+1), r, h, floor(m…

Importing an existing SSL key/certificate pair into a Java keystore

I'm writing this blog post in case anyone else has to Google that. In Java 6 keytool has been improved so that it now becomes possible to import an existing key and certificate (say one you generated outside of the Java world) into a keystore.

You need: Java 6 and openssl.

1. Suppose you have a certificate and key in PEM format. The key is named host.key and the certificate host.crt.

2. The first step is to convert them into a single PKCS12 file using the command: openssl pkcs12 -export -in host.crt -inkey host.key > host.p12. You will be asked for various passwords (the password to access the key (if set) and then the password for the PKCS12 file being created).

3. Then import the PKCS12 file into a keystore using the command: keytool -importkeystore -srckeystore host.p12 -destkeystore host.jks -srcstoretype pkcs12. You now have a keystore named host.jks containing the certificate/key you need.

For the sake of completeness here's the output of a full session I performe…