The focus of this book is “monetizing your application with payment flows.” That’s a high-toned way of saying Click here to spend some money or Click here to pay your bill or Click here to donate.

PayPal APIs: Up and Running, 2^nd Edition shows how to work with PayPal’s platform, which “offers a vast number of API-based products that allow you to monetize your ideas as seamlessly as possible.” (APIs are application programming interfaces.) The book is written clearly and is well illustrated with diagrams, code examples, screen shots and tables.

According to the author, PayPal’s Name-Value Pair (NVP) Application Programming Interfaces (APIs) make it “simple to integrate payments into your applications.  As the merchant, your web application constructs an NVP string and transmit(s) it via HTTPS (HTTP Secure) to the PayPal authorization server, and PayPal sends back an NVP-formatted response that your web application parses for the information relevant to the payment.”

What Matthew A. Russell’s book does not do is “provide complete or exhaustive documentation on all of PayPal’s products or even provide very specific direction on handling some of the most common idiosyncrasies that you might encounter.” But it does “aim to present some of the most popular products in fully integrated realistic scenarios with sample project code that you can study and adapt for your particular needs.” It shows you how to get started and points you toward sources of more advanced information.

Rather than introduce a new, “distinct sample application” in each chapter, the author’s approach is to use a single, simple application “as a foundation,” and “customize it in various ways according to the content of each chapter….” And the chapters are structured to be mostly standalone.

Early in the opening chapter, the foundation application is built using Python and Google App Engine (GAE). And you begin working with PayPal’s APIs.

The 135-page book is organized as follows:

• Chapter 1: PayPal API Overview
• Chapter 2: Express Checkout (Including Mobile Express Checkout)
• Chapter 3: Express Checkout for Digital Goods
• Chapter 4: Adaptive Payments (Simple, Parallel, and Chained Payments)
• Chapter 5: Website Payments Pro (Direct Payment)
• Chapter 6: Instant Payment Notifications (IPNs)
• Appendix A: Overview of Tweet Relevance - Tweet Relevance is the book’s sample application, “implemented in Python (one of the easiest-to-read programming languages), runs on Google App Engine (a web application platform that is mature and extremely well documented), and munges data from Twitter (an accessible and extremely rich source of information),” Russell writes.
• Appendix B: Mobile Payment Libraries (MPLs) – Goes beyond the scope of this book. Contains brief information on PayPal’s MPLs, including creating “in-app purchases for iOS, Android, and BlackBerry,” and gives guidance for finding more information.

Each chapter also contains recommended exercises, and the book’s code examples are available online.

The first edition of PayPal APIs: Up and Running was written by Michael Balderas. PayPal APIs: Up and Running, 2^nd Edition builds upon his foundation and covers some new aspects and products of PayPal.

If you are a programmer who wants to accept payments for goods or services through PayPal or help a client accept online payments or donations, you should consider getting this useful and well-focused book.

– Si Dunn

#

I’m planning to do a web application to use with it and I’m developing a website in Django/Python to implement the timetable with a search for routes.

The final goal will be to put a “I’m here” button which would tell the nearest stop and tell you the next useful bus to catch.

After learning a bit of Python to work with the Tumblr API I’ve noticed that it’s a quite nice web oriented language to use, so I choose it in combination with the Django project and programming dynamic web pages it’s not as bad as I remembered from high school.

You can find if you want the source files in this Bitbucket repository!

I got to play with this ‘little’ cutie for a few minutes.

I think yellow is my colour.

I stumbled upon the singleton pattern while reading a PHP book and fell in love with its simplicity. I rushed to use it at every single opportunity I got (when you have a hammer, everything looks like a nail, right?) until I got tired of it; now I can’t really remember when I used it last. Why? Well, there has been no reason to. Singletons have been the topic of heated debates over time, some people even consider them to be an anti-pattern! But first, what is this pattern all about?

The Singleton pattern is a design pattern that ensures that only one object of a class exists. Singletons are best used when you need to have a single object control simultaneous access to shared resources by other objects. If this conditions are not met, you should consider another design.

So how do I create a Singleton?

Blosch in Effective Java listed these two ways: exposing a member variable and using a static factory.

Using a public member variable

public class Singleton {

public static final Singleton instance = new Singleton()

private Singleton() {…}

//other code

}

Using a static Factory

public class Singleton{

private static final Singleton instance = new Singleton()

private Singleton() {…}

public static Singleton getInstance(){

if (instance == null)

instance = new Singleton()

return instance

}

//other code

}

Why are Singletons used?

A good application of Singletons is in logging; you’ll probably want to log all events from the various classes in your project to a single location. So it is best to use a singleton to write, synchronize writes and close the file. They can also be used to read static configuration files at startup and provide all other classes with initialization details.

Great! So why the fuss about Singletons? Well, Singletons (like all other misuses occurring in software engineering) are not the problem; people are. When used by people without a strong grasp of OO concepts, they can turn into humongous monstrosities that cause unnecessary restrictions and bring in global state. Worse still, they’ll be used when they is absolutely no need for them or what they were not designed to do.

Enough talk about ugly code… Here are some of the issues:

• Memory Management: How does garbage collection occur? Well no one knows that the single instance has not been used for a long loooong loooooooooooong time. And how do you know if some remote class has a reference to the single instance?

• Singletons are hard to subclasss; it is pretty difficult to override the default initialization sequence.

• Worse still, try handling multithreaded singletons.

• It is difficult to test Singletons and they can cause code to become tightly coupled.

So you might thinking Singletons are evil now; no not quite. Singletons pros include:

• Singletons can implement interfaces and inherit from other classes.

• They can be lazy-loaded (most times they are); this is great for expensive resources.

• They can be easily converted into factories.

Should I use a Singleton?

I have only one thing to say; Learn about it well enough else you’ll be using a hammer to drive in a pin!

My Good Man and I were in the Grampians for a wedding on the weekend. As the following morning was clear, after a leisurely cafe breakfast we decided to walk off the overindulgence at Halls Gap Zoo. (Visiting zoos is one of the few times we are content to walk together for longer than a few minutes – most of the time there’s a lot of “come for a walk?” and the reply, from him, “have fun!”)

According to Wikipedia, the zoo was opened in the 1980s as a wildlife park; indeed, I remember visiting it in the mid ’80s with my mum and a friend from North Dakota. It’s just the kind of place overseas tourists love to visit, with lots of native wildlife to be seen up close. At that time, there was also a lot of deer, and we bought bags of food to give them. That would have been the highlight for me.

Yesterday we weren’t seduced by the promise of being able to feed the wildlife (the still-prolific deer tried to eat the map anyway), but we did enjoy ourselves, and it was a pleasant walk through the exhibits too.

At the doorway to the park stood the Peacock of Greeting, who stepped casually out of the way to let us pass. When we headed into the nocturnal house, I became quickly besotted with the Veiled Chameleon in the entrance, who was doing a super-slow-motion dance. Chameleons are several kinds of awesome: one – they’re so colourful; two – their eyes swivel around independently of each other; three – they catch their prey with a very long, sticky tongue; four – curly, whirly, tail; five – this one had a helmet. I’m sure there is yet more awesomeness to be discovered.

The Pygmy Marmosets were my favourite exhibit – they seemed to be as engaged in the act of looking at the amazing creature behind the glass as we were. They also looked disconcertingly intelligent, and as though a finger would be a welcome treat.

In the fossil house, the static displays were enhanced by the inclusion of reptile exhibits. The python, though its neck was outstretched, was quite immobile and I wasn’t even quite sure it was alive!

The walk through the open air exhibits took us into a roaming band of hungry deer, who trailed along behind as we saw wallabies, emus, a cassowary, bison, a hyper Phascogale, native quolls, Tasmanian devils, owls, corellas, parrots, Bush stone-curlews, a bustard, meerkats, red pandas, spider monkeys, antelope, Barbary sheep, and many more besides. It was well worth the visit.

I came down the stairs and stepped into the car park but between me and the car was a large diamond python and I backed off quickly! Another visitor hit the concrete floor with his paper and the snake turned left and went between the cars and (I hoped) out into the garden. 

Carefully I retrieved the item from the boot, but when getting into the front of the car I jumped in instead of reaching in… retrieved what I wanted and quickly made my way back up the steps.

Of course, you can guess the reaction to my news about a 2 metre diamond python…..just like every big fish story! We left Coffs the next morning, stopped in Grafton for fuel and to clean the windscreen and went onto Casino where we spent and enjoyable hour and a half visiting relatives before resuming the journey up through Kyogle.

We had just passed through Wiangaree, heading uphill through a cutting when Ross said “I know where your snake is!”. I looked up to see the head of the snake coming down onto the bonnet of the car. We were unable to stop and had to continue over the hill and out of the cutting before pulling over.

“You stay in the car and I’ll try to find a stick to get the snake off”. Beryl and I looked at each other – there was no way known to man that we were getting out of that car! Luckily our friend had had enough of cars and happily descended – last seen heading for the wide open space of the adjacent paddock. Husband and sister-in-law agreed that I had not exaggerated the size of the python!

Mavis

So, the problem is that everything works fine when I copy something like

http://example.com/

or something like

http://example.com/

but it doesn’t work anymore when the link is like

this is a link to an example domain

And, since I’m lazy, I decided I had to write a program to copy a bunch of links at once, without all that hassle. The first idea that came to my mind was to write a Python script that used mechanize to copy to the clipboard all URLs in a web page, but that didn’t seem like the prettiest solution at that moment.

But then a second approach occurred to me: I could just copy the web page’s text to the clipboard and let a program read the richt text, HTML or whatever from the clipboard and find the URLs. Besides, that seemed to be an interesting program to write. I started considering RubyCocoa for that, but a deep knowledge of sorcery is needed to be able to use Xcode, and I’m not such a good sorcerer. After that, my tests with Qt weren’t successful, so I decided to go search on the internet for some recipes to access the OS X clipboard with Python.

After digging for a while, I found and article on Python and the Mac Clipboard which pointed me in the right direction: use PyObjC to access the NSPasteboard class. After taking a look at the documentation and testing a bit, supported by Python’s built-in dir() and help() functions, I found that

1. all of the items that are currently in the pasteboard are returned as an NSArray by NSPasteboard.pasteboardItems method,
2. the list of all types to which each pasteboard item can be converted is returned as an NSArray by the NSPasteboardItem.types method, and
3. all text copied from Safari can be accessed both as com.apple.webarchive with the NSPasteboardItem.dataForType_ method, and as public.rtf with the NSPasteboardItem.stringForType_ method.

from AppKit import NSPasteboard

import re

pb = NSPasteboard.generalPasteboard()
pattern = re.compile(r'HYPERLINK "(.+)"')
for item in pb.pasteboardItems():
	if 'public.rtf' in item.types():
		matches = pattern.findall(item.stringForType_('public.rtf'))
		for url in matches:
			print url

You can then copy the output URLs manually to the clipboard, which would make jDownloader to recognize them, or you could also improve the script to add copying capabilities, so that the script would copy the output to the clipboard again.

First off, I will introduce you to the superclass that every class you create in Python inherit methods from: Object. Object have a few built in methods that can be very valuable when you create your own class. I however will just focus on a few in this post, that I have used myself in a small assignment at the university.

To create a class, you start off with simply:

class Classname(): It’s not needed to add Object into the brackets, if nothing else is said the class will inherit Object. If you want you can do it, but it is not necessary.

After this we want to define the __init__() method. It does not return anything, __init__() is just resposible for initializing an instance (the object’s data attributes) of the class when it is created in memory.

Here you can see that I have created a class called Rectangle. Notice the (self) parameter. When a method in the class is executed it must know which object’s data attributes it should operate on. So the self parameter is a reference to the specific object the method is supposed to operate on.Since I want this class to handle input to calculate a rectangle’s area and circumreference the __init__() method also accepts arguments for height and width, which are assigned to the self. __height and self. __width attributes. Two underscores befrore the attribute name makes the attribute private, and can not be manipulated or changed by methods outside the class.

I wanted this class to be able to calculate the area and circumreference of a rectangle I need to define a few methods to make that possible. I’ve choosen to make methods to handle the height, width and also the calculations needed.

Starting off with def getHeight(self): what happens here is that the value stored in the attribute self.__height is returned. The same goes for def getWidth(self):.

In getArea(self): and getCircumreference(self): more happens than in the above methods. Starting off with area, the method returns the sum of the value stored in the attributes self.__height multiplied with the value stored in self.__width.

In getCircumreference(self): we need to have the width multiplied by two and add that to the height multiplied by two. To make sure we get the correct calculation, we have to separate the calculation for 2 times the value of self.__height and the same calculation for self.__width and then add the two values together. Basically just what you could do normally when calculating math.

To see if my class works propperly I make a test program in another file and import the file with the class in it.  You define your main method and then create as many instances of the class you want. I have done two in this test. You add the height and width of the rectangles within the brackets, for example r1=rectangles.Rectangle (8,3). Then to use the methods within the class module you created, you use rectangles you created to call on the methods r1.getCircumreference().

Rainbow Parrot

Glossy-eyed Python

Iguana

Iguana (close up)

Shark

Here, four possibilities I explored in order to fix this issue:

• The painful way: you can modify relevant files, and run additional scripts before re-compiling your main tex document each time it is required.
• The dirty way: you write a shell script that takes care about re-building things. This script is likely to be not pretty smart: it would probably not handle properly dependencies, timestamps and cross-references.
• The old-school way: use (GNU)Make, write your own Makefile is not difficult. However Makefile syntax is awkward and writing a complicated one (which will manage dependencies and fire bunch of shell commands appropriately) is tedious too.
• The Pythonic way: use Scons, it is a modern (literally) Software CONStruction tool like Make but is based on the Python language and work very well with LaTeX documents.

It provides some very interesting properties:

• Scons include a built-in LaTeX mode: it cares for you about cross-references and dependencies of your master document. That is it detects automatically all files (text/pictures/bibfiles) included in your master tex document (and recursively in the sub-documents), verifies their current state and re-build them accordingly.
• It allows for complete use of the python language and all its capabilities, if you want to add some piece of script directly in your Sconstruct file..
• It allows for an easy handling of particular cases through user-defined Builders and dependency Scanners.

To get to work, Scons only requires a very simple Sconstruct file in the project’s directory:

import os

SRC = 'main.tex'
env = Environment(ENV=os.environ)

pdfOutput = env.PDF(SRC)

Then the scons command will do the job. In this example we used the PDF Builder but Scons supports DVI() and PostScript() output as wel.

However, may be you want to add some features such as Rich Text Format output:

...

rtfbuilder = Builder(action='latex2rtf $SOURCE',
suffix = '.rtf',
src_suffix = '.tex')

env = Environment(ENV=os.environ)

env.Append(BUILDERS = {'RTF' : rtfbuilder})

rtfOuptu = env.RTF(SRC)

User-defined builders could be also helpful in joint use of LaTeX and the R language through Sweave. Let’s assume that we include in our master document a tex file that is remotely defined by a Sweave (.Rnw) file. In this case we surely want to add a Sweave builder.

...
sweavebuild = Builder(action='./Sweaver.sh $SOURCE',
suffix = '.tex',
src_suffix = '.Rnw')

env = Environment(ENV=os.environ)

env.Append(BUILDERS = {'SWeave' : sweavebuild})

swvOutput = env.SWeave('remote_sweave_file.Rnw')
pdfOutput = env.PDF(SRC)

The sweavebuild action parameter could be set either with the classic R CMD interface or with a Rscript in order to give some explicit parameters to Sweave (e.g., the script below use explicit ‘latin1′ character encoding because implicit encoding does not work  with some old release of R):

#! /usr/bin/env Rscript
args <- commandArgs(TRUE)
Sweave(args[1], encoding='latin1')

pyherc is my pet project that I have been working in a form or another for years. It all started back in the 90s, when I wanted to program the greatest rpg-game ever. I was using Turbo Pascal back then and learned quite a bit about basics of object oriented programming, but never got the game even to run.

Next try was some years later when I started learning C/C++ and tried writing the game again. Success was about as good as with Turbo Pascal (so, I learned how objects work in C/C++ and how easy it is to get tangled to little details), but again I didn’t get a playable game.

Then came Java and I thought it would be useful language to learn (I also liked the amount of libraries available out there) and I started hacking the code together. This time I actually got runnable game, where you could walk around, pick up and eat bananas and kill some randomly wandering monsters. This was also the first time I was exposed to unit testing. I wrote some of those, but the approach was not very structured or disciplined. Despite of that, I quickly realised that writing unit tests was good way to catch bugs before you could even run the code in actual game. Eventually I gave up with the game though and abandoned it.

Latest try has been written with Python. So far the results have been much better than before. I have playable game (albeit very basic) with extensive test cases around it. I’m trying to maintain healthy pace (not coding too much, not abandoning the project completely), while learning and trying out new things (inversion of control, dependency injection, doctests and so on). The game isn’t anything particularly special, but I’m quite proud that I finally got this far. Lets see where next 500 commits will take me.

import sys, os, random, time

if len(sys.argv) < 3:
    print "Usage: youtube_pl2vids [playlist.html] [destination directory]"
    sys.exit(1)

source = sys.argv[1]
dest = sys.argv[2]
urllines = []
f = open(os.path.join(dest, 'youtube.dl'), 'w')
for line in open(source, 'r').readlines():
    if '<a href="/watch?v=' in line and 'class="tile-link-block video-tile"' in line:
    url = "http://www.youtube.com" + line.split('&amp')[0].split('<a href="')[1]
    f.write(url + '\n')
    urllines.append(url)
f.close()
print urllines
# we assume youtube-dl is installed
for line in urllines:
    os.system('youtube-dl -t --max-quality 22 %s' % line)
    s = random.randint(1, 6)
    print "sleeping %s secs" % s
    time.sleep(s)

Revise:

Python dictionary and file handling tutorial.

Guess Damen Armbanduhr G2G Python W13089L1
Unverb. Preisempf: EUR 209,00
Preis: SEHEN PREIS!

<< MEHR INFOS | SEHEN PREIS >>

Guess Damen Armbanduhr G2G Python W13089L1 Produktbeschreibungen

Diese Halbspangenuhr von Guess ist mit Schlangenmuster verziert. Das Mineralglas ist kratzunempfindlich. – 2 Jahre Garantie… Lesen Sie weiter >>

Guess Damen Armbanduhr G2G Python W13089L1 Produktmerkmale

• Antrieb/Genauigkeit: Quarz
• Armband-Farbe: braun
• Display-Anzeige: Analog
• Gehäuse Durchmesser ca. (mm): 30
• Gehäuse-Material: Edelstahl

Guess Damen Armbanduhr G2G Python W13089L1 Kundenrezensionen

Klicken um zu sehen Kundenrezensionen >>

<< MEHR INFOS | SEHEN PREIS >>

Choose Country

The Guess Damen Armbanduhr G2G Python W13089L1 possibly for sale in your local merchant’s site. Please choose your country below to get the benefit of a shipping rates.

• United States (USA)
• Canada
• United Kingdom (UK)
• Deutschland (Germany)
• France
• Italia (Italy)
• Espana (Spain)

ETTAB Blog (ettabblog.wordpress.com) is a participant in the Amazon Services LLC and Amazon EU Associates Programmes designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com, amazon.ca, amazon.co.uk, amazon.de, amazon.fr, amazon.it and amazon.es. Certain content that appears on this website comes from Amazon Services LLC and/or Amazon EU. This content is provided “as is” and is subject to change or removal at any time.

PyFITS has convenience functions for working with FITS headers but as of version 3.0.7 it doesn’t come with any scripts that make them accessible from the command line. I expect that soon PyFITS and/or AstroPy will have these scripts, but in the meantime here are the ones I use.

imhead

This wraps pyfits.getheader to print an image header to the terminal. There are options to specify an extension header or only certain keys to print. See the code here: https://gist.github.com/1394499.

Examples

Print an entire header:

> imhead jb1f98q1q_raw.fits

Print an extension header:

> imhead -e 1 jb1f98q1q_raw.fits

Print only certain keywords (case insensitive):

> imhead jb1f98q1q_raw.fits -k expstart -k expend

My most common usage is to print the entire header but pipe the output to grep so I don’t have to remember the exact keyword names:

> imhead jb1f98q1q_flt.fits | grep OBS
DATE-OBS= '2009-12-03' / UT date of start of observation (yyyy-mm-dd) 
TIME-OBS= '02:25:29' / UT time of start of observation (hh:mm:ss) 
OBSTYPE = 'IMAGING ' / observation type - imaging or spectroscopic 
OBSMODE = 'ACCUM ' / operating mode

hedit

This wraps pyfits.setval to enable modification of headers from the command line. It supports modification of multiple files with one call, changing extension headers, and specifying the keyword type. See the code here: https://gist.github.com/1394486

Examples

Modify a single file:

> hedit jb1f98q1q_raw.fits EXPSTART 58000 -i
jb1f98q1q_raw.fits[0]: EXPSTART -> 58000

Modify multiple files:

> hedit *.fits FLATCORR PERFORM

Modify an extension header:

> hedit jb1f98q1q_raw.fits SOMEKEY SOMEVALUE --ext 1

Usage

To use these yourself copy the code to a local file wherever you keep scripts and set them to executable. The files I linked above require Python 2.7 because they use the argparse module, but if you are using an older version of Python I’ve also written versions of these using optparse. Those versions are at https://gist.github.com/1401692 (imhead) and https://gist.github.com/1401666 (hedit). Enjoy!

My younger brother came in to see what I’m doing, he expressed how he wants to learn Java so he can ‘make Minecraft mods.’  That’s all fine and all, but it made me realise that I should explain what I’m trying to acheive out of doing this.  I said I want to produce software in my first post, but what kind of software? All I can say is software that will make a positive impact on humanity.  You know, things like programming The Large Hadron Collider.  However, I want to be recognised for it aswell. Yesterday, Facebook was sold to the public at a market cap of 104 billion and it all started from Mark Zuckerberg creating a killer app.  Now, I don’t like Facebook however I don’t see it just as a social networking site I see it as a tool for businesses to publicise to specific audiences.  AKA, a marketing tool.  And THAT’S why it’s worth loads.  It engages people of specific interests, to consumerise or spread a message.  I want to become the next Mark Zuckerberg, except I want innovation – not marketing.

(Excluding the fact that Facebook is innovation IN marketing).

“Business is about two things: Marketing and innovation.”