You probably already figured this one out if you use git. But if you’re new to all of those awesome git tricks, well, here you go.
I always forget to checkout the branch I just created, so having it wrapped up in a single command is absolutely perfect.
git checkout -b [name of new branch]
That takes care of doing git branch [name of new branch] followed by git checkout [name of new branch]. Time saving and convenient.
Happy commiting!
Adding a jar to an eclipse project is normally really easy. I came home from school today after adding the AP Computer Science gridworld jar. I always have to add external libraries twice because at school we have OSX and at home I have Windows, so the file paths don’t match up.
So after trying to add the jar, I got this error.
“setting build path” has encountered a problem. Could not write file (Access is denied)
I thought that perhaps Eclipse required Administrative permissions to write to the classpath file. That didn’t make it any better. I recalled that Eclipse does some screwy things with file paths.
I did a little searching and I eventually came upon a blog with some instructions on the problem.
I kept getting this message in eclipse when attempting to change the dependencies under the project properties. The cause was copying a workspace from Linux to Windows. The windows hidden attribute is set on the .classpath file. Removing this attribute fixes the error.
After going into the workspace and project directory, I removed the hidden attribute. Eclipse was able to add the jar to the project perfectly after that.
On a recent project, I used ajax to render a full cell of a table upon clicking it. I found that without some kind of queue, my clients would click on a bunch to expand them, but only the first would render. Mootools offers a plugin in mootools more called Request.Queue, but that wasn’t what I was looking for, since there was only a single Request object involved, not multiple.
I was reading the documentation of Request to see if I missed something, because I thought this was core functionality. Apparently, there is something built into mootools more that does just that, it chains requests, literally forming a queue.
Straight from the options of Request:
‘chain’ – Any calls made to start while the request is running will be chained up, and will take place as soon as the current request has finished, one after another.
Adding that option to Request worked perfectly, so I was able to click on a bunch of table cells and let them render freely.
I think that there should be a note in Request.Queue that there is already functionality for repeated requests with the same Request object built into the core.
Today I was using one of CakePHP’s helper methods, $text->truncate. It gave me these errors and I can’t say I was pleased about it. It reminded me that sometimes, functions aren’t a piece of cake.
Warning (2): array_merge() [function.array-merge]: Argument #2 is not an array [CORE/cake/libs/view/helpers/text.php, line 184]
Warning (2): extract() [function.extract]: First argument should be an array [CORE/cake/libs/view/helpers/text.php, line 185]
Notice (8): Undefined variable: html [CORE/cake/libs/view/helpers/text.php, line 187]
I also used it in the same view a little later. It gave errors down there as well.
Notice (8): Undefined variable: ending [CORE/cake/libs/view/helpers/text.php, line 238]
Notice (8): Undefined variable: exact [CORE/cake/libs/view/helpers/text.php, line 241]
Notice (8): Undefined variable: html [CORE/cake/libs/view/helpers/text.php, line 244]
Notice (8): Undefined variable: ending [CORE/cake/libs/view/helpers/text.php, line 258]
Notice (8): Undefined variable: html [CORE/cake/libs/view/helpers/text.php, line 260]
I wasn’t sure what was going on, so I went into the CakePHP source code to check it out. Traveling to cake/libs/view/helpers/text.php, I found the truncate method. Check out the code for it.
function truncate($text, $length = 100, $options = array()) {
$default = array(
'ending' => '...', 'exact' => true, 'html' => false
);
$options = array_merge($default, $options);
extract($options);
// continues
}
This code is expecting only two real arguments. The third is a magic options array. Apparently nobody has thought about updateing the CakePHP book. Of if they have made updates, forget to tell people by putting a huge notice somewhere. The documentation explains the new arguments quite well, actually.
To fix those errors, I simply didn’t use any extra arguments, as I was satisfied by the defaults. But I could easily specify some other options.
__( $text->truncate($problem["Task"]["description"], 75) );
// other options
__( $text->truncate($problem["Task"]["description"], 75, array("ending" => ". . .", "exact" => false, "considerHtml" => true)) );
My favorite feature about this is the exact option. It doesn’t chop up words, which is great.
I recently deployed a CakePHP application to a 1and1 server. I was presented with a wonderful 500 Internal Server Error. That only means one thing: a .htaccess was messed up somewhere.
There were many places that pointed me in the right direction to fix this problem. It was definitely an annoying hitch. Seriously, there’s that many people with this problem. (So 1and1, want to help out here and make some changes? Maybe, just maybe, provide an customer error.log?)
Anyway, there is a pretty simple way to do this, since I did it this way too.
RewriteEngine on
RewriteBase /
RewriteRule ^$ app/webroot/ [L]
RewriteRule (.*) app/webroot/$1 [L]
I simply added a RewriteBase / to every single .htaccess, the one in the root folder, then one inside app and inside webroot.
1and1 has a reputation for making things complicated, but this wasn’t so bad.
CakePHP does make somethings really easy, and sometimes, not so easy. I like to have a testing setting and a production setting stored in my databases.php. Your DATABASE_CONFIG object of course contains those arrays of settings. So the question is, how do you switch exactly?
It is never mentioned specifically in the documentation, but you can do it by using the AppModel class.
class AppModel extends Model {
public $useDbConfig = "testing";
// public $useDbConfig = "production";
}
What’s great about this setup is that, while on your testing server, it works with your local database. You can then upload this along with the rest of your CakePHP application. Once on your remote server, either via SSH and VIM or simply an FTP file-edit, you can comment out $useDbConfig = "testing" and uncomment public $useDbConfig = "production".
This is super-model is extended by every model you use in your application. That way, every single model will also use those database settings. This is an incredibly easy way to manage different server environments.
My Computer Science discovers interesting things sometimes. Recently we were doing a little practice with Exceptions and try-catch blocks. One of our projects was to handle division by zero and not crash the program. That sounds like a ordinary project, but as it turns out, it was a more surprising than anyone would have ever thought.
To practice, numbers without a decimal are simply integers, otherwise, they are a double.
5 / 2 = 28 / 3 = 210 / 0 = NaN // impossibleYou understand integer division just fine right? You can divide a number freely, but there are no decimals, it simply chops off the remainder and any would-be decimals. Division by zero typically throws a Arithmetic Exception.
Something weird happened when those numbers were doubles.
Try out this code. You’ll be surprised.
class DoubleDivision {
public static void main(String[] args) {
System.out.println( 5.0 / 0.0 );
}
}
Did you try it? Did you get Infinity? I bet you did. That’s kind of weird.
Java uses Doubles to represent decimals. Binary cannot fully represent a number, it can only represent an approximation and therefore, neither can Java’s double.
Imagine a number incredibly close to zero. If you know calculus, imagine a limit at zero. The variable would be approaching zero to some imaginably tiny distance but never equal exactly. You can imagine that, right? Well, suppose that number is needs so much percision for Java to represent, it gives up and calls it 0.0 because it does not have a good alternative. That’s what is happening here. Any regular number divided by a super close number to zero is basically, infinity. Try it: 5 / (10^-100).
The Double Class documentation attempts to explain some of the toString details. The documentation does not explain this case, but as mentioned above, it might as well be infinity.
So if you divide by zero, and you are using doubles, watch out for Infinity!
Firebug will scream and shout about Invalid Object Initialization if you mess just a little something up. Firebug does this a lot. It is an unhelpful error because Firebug will direct you to the first line of your object, not where the problem is.
Firebug gave me this, more or less. That wasn’t helpful. (Why did Firebug get full, anyway?)
Firebug’s log limit has been reached. 0 entries not shown. Preferences invalid object initializer[Break on this error]
Let’s say you have some code, and it looks like this.
var TranslationStrings = {
onAdd: "Do you want to add this?",
onDelete, "Do you want to delete this?"
};
If you don’t notice the mistake in the object, Firebug will. It’s just a little something. It is a comma.
The onDelete, "Do...." should have a colon between the key-value pair. Not a colon, those go after a pair. It should be formed like so, onDelete: "Do...".
So remember, watch out for those javascript object literals with commas and colons.
When I get a new computer I always do a couple of things immediately upon getting to the Windows Desktop. One of those things is enabling the showing of extensions and hidden files. You should do it too, it can save tons of headaches.
Folder Options - File Extensions and Hidden Files
That’s all there is too this. Whenever I use a friends computer, I ask them if I can make the change, as they don’t often know they can do it.
I recently converted my old Windows Vista computer into a Ubuntu server after getting tired of my old virtual box virtual machine. It still had a decent graphics card (an nVidia 9500 GT) so I wanted to at least checkout Compiz Fusion. I had some trouble getting it up though. So here’s the deal.
As my physics teacher says, “Give it a go.” I did. I put the ubuntu disc in and followed it into the live CD mode so I could format my drive visually. That worked and then it was installing. Since I had wireless already enabled, Ubuntu told me that there were nVidia drivers available for my graphics card. So I gleefully obliged and selected the most recent driver for my card listed, it was the 185 build, I think. So then it completed the installation. Good. Restart.
Bad.
Of course nothing is that easy. I basically encountered the following: the GRUB loaded, and then Ubuntu modules tried to load, but then the GUI didn’t come up. Instead, it said to me:
ttyl
That’s it. But it was flickering too. Hoping for help via a search but no viable dice. So I was daunted and I took a break. It was sunday night, so the break happened to be for a week.
A solution to the ubuntu 9.10 ttyl flicker is to reinstall Ubuntu. Here’s my procedure.
This worked for me and hopefully it will work for you. If you need more help, you can always try out the ubuntu forums.