Cross-Platform


The Pony ORM project is another object relational mapper package for Python. They allow you to query a database using generators. They also have an online ER Diagram Editor that is supposed to help you create a model. They are also one of the only Python packages I’ve seen with a multi-licensing scheme where you can develop using a GNU license or purchase a license for non-open source work. See their website for additional details.

In this article, we will spend some time learning the basics of this package. (more…)

I thought it would be fun to try out a few different Python object relational mappers (ORMs) besides SQLAlchemy. I recently stumbled across a project known as peewee. For this article, we will take the examples from my SQLAlchemy tutorial and port it to peewee to see how it stands up. The peewee project supports sqlite, postgres and MySQL out of the box, which isn’t as flexible as SQLAlchemy, but it’s not bad either. You can also use peewee with the Flask web framework, via a handy Flask-peewee plugin.

Anyway, let’s start playing around with this fun little library!

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Redirecting stdout seems to be a pretty common request on the wxPython users group, so I decided to see how easy it would be to do it with Tkinter. The typical use case for redirecting stdout or stderr is that you are calling some other process (like ping or tracert) and you want to catch what it’s doing to put it into your UI. Usually you can just use Python’s subprocess module and call its communicate() method to access the data. Then you can just print it to stdout and it will magically appear in your UI’s widget of choice.

Our finished user interface will look something like the following:

tkredirect.png

Let’s find out how to do this with Tkinter: (more…)

I’ve been using wxPython for quite a while now and I see certain questions come up on a fairly frequent basis. One of the popular ones is how to ask the user for their credentials before loading up the rest of the application. There are several approaches to this, but I am going to focus on a simple solution as I believe this solution can be used as the basis for more complex solutions.

Basically what we want to happen is for the user to see a login dialog where they have to enter their username and password. If they enter it correctly, then the program will continue to load and they’ll see the main interface. You see this a lot on websites with a common use case being web email clients. Desktop applications don’t include this functionality as often, although you will see it for Stamps.com’s application and for law enforcement software. We will be creating a dialog that looks like this:

wxLogin.png (more…)

Last year there was an Indiegogo crowdfunding campaign in support of PyDev, the Python IDE plugin for Eclipse. It was put on by the primary developer of PyDev, Fabio Zadrozny. As a part of that campaign, Fabio also created LiClipse.

Anyway, Fabio is at it again with a new crowdfunding campaign. You can read about it here. Fabio has two targets for this campaign. The first is adding the following features to PyDev:

  • Allow preferences which are currently global to be configured per-project.
  • Provide a proper way to export/import PyDev settings to a new workspace.
  • Suport for namespace packages in code-completion.
  • Provide a way to auto-document types as well as checking existing types in docstrings when doing a test run.
  • Allow running an external pep8 linter (to support newer versions of pep8.py).
  • Show vertical lines for indentation.
  • Attach debugger to running process (although some caveats apply and under certain circumnstances this may not be possible).
  • Other requests to be defined based on community input as funding allows.

The second is, in my opinion, a bit more interesting. Fabio is planning on writing a profiler for PyDev that can also work outside of PyDev using Python and Qt. He has a list of features for the profiler listed in his campaign. It sounds pretty interesting. It should also be noted that PyDev and the proposed profiler will be open source, so you can always check out how the code works behind the scenes.

If you think either of these items sound interesting, then you should consider supporting Fabio in his endeavors.

eGenix announced this week that they were releasing an “open source, one file, no installation version of Python”. You can read their entire announcement in their press release here. If you want to check out the actual product, you can get it at the following URL: http://www.egenix.com/products/python/PyRun/.

This is a Unix-based Python and they state that they only provide Linux, FreeBSD and Mac OS X, as 32- and 64-bit versions, so if you’re a Windows guy, you’re out of luck. I think one of the coolest aspects of this tool is that it’s 11MB for Python 2 and 13MB for Python 3, but it still supports most Python applications and code that you’ve written. If you write a lot of code that depends on 3rd party utilities, than I don’t think PyRun will be very helpful to you. But if you depend mostly on Python’s standard library, than I can see this as a very handy tool.

An alternative to PyRun would be Portable Python which provides a large number of 3rd party libraries that are baked in with the standard library. I’ve used Portable Python in several applications of my own where I didn’t want to install Python itself. Anyway, I hope you find this information useful in your own endeavors.

Every once in a while, I run into a situation where I need dummy data to test my code against. If you need to do tests on a new database or table, you will run into the need for dummy data often. I recently came across an interesting package called Faker. Faker’s sole purpose is to create semi-random fake data. Faker can create fake names, addresses, browser user agents, domains, paragraphs and much more. We will spend a few moments in this article demonstrating some of Faker’s capabilities. (more…)

Recently I ran into an issue where an application that calls Python would insert int into Python’s namespace, which overwrites Python’s built-in int function. Since I have to use the tool and I needed to use Python’s int function, I needed a way around this annoyance.

Fortunately, this is fairly easy to fix. All you need to do is import int from __builtin__ and rename it so you don’t overwrite the inserted version:

from __builtins__ import int as py_int

This gives you access to Python’s int function again, although it is now called py_int. You can name it whatever you like as long as you don’t name it int.

The most common circumstance where one shadows builtins or other variables is when the developer imports everything from a package or module:

from something import *

When you do an import like the one above, you don’t always know what all you have imported and you may end up writing your own variable or function that shadows one that you’ve imported. That is the main reason that importing everything from a package or module is so strongly discouraged.

Anyway, I hope you found this little tip helpful. In Python 3, the core developers added a builtins module basically for this very purpose.

Last month we looked at how to create Microsoft Excel (i.e. *.xls) files using the xlwt package. Today we will be looking at how we can read an *.xls/*.xlsx file using a package called xlrd. The xlrd package can be run on Linux and Mac as well as Windows. This is great when you need to process an Excel file on a Linux server.

We will start out by reading the first Excel file we created in our previous article.

Let’s get started! (more…)

Reportlab recently released version 3.1 which now fully supports Python 3 and Python 2.7. They had actually released a Python 3 compatible version about a month or so ago, but this one sounds like they’ve worked the bugs out of that initial release as this version also supports their commercial customers. I find this exciting in that one of my favorite Python packages finally supports Python 3. I haven’t moved to Python 3 myself because I use so many packages that are only available for Python 2 (and also because I have yet to work for a place that uses Python 3). There aren’t really any awesome new features in Reportlab 3.1 as of yet, but you can read through their release notes and decide for yourself.

One cool new feature of Reportlab is that you can now install it with pip or easy_install. They have also introduced Python wheel packages as their primary installation type, although you can still download the source. See PyPI for the open source downloads.

Check it out and let me know what you think!

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