Open specific file type with Python script?

Question

How can I make a Python script to be a specific file type's (e.g., *.foo) default application? As in, when I double click the file in the Finder / Explorer I want the file to open in the Python script.

Is this possible to do in Win and/or OS X? The application is a PySide app if that matters.

Answer 1

On Windows:

1. Right click the file (I used a .docx file for this example)
2. Select Open with...
3. From the applications list, select python
4. Optional: Select the Always use the selected program to open this kind of file.

Note: this will run the contents of the .docx file in context of the python shell. It will immediately close once it is finished evaluating the contents of the file. If you'd like to edit the file in a word processor, perhaps you should download notepad++, and select that application as the default.

Answer 2

I found this old question while looking for an answer myself, and I thought I would share my solution. I used a simple c program to direct the arguments to a python script, allowing the python script to stay a script instead of needing to compile it to make things work. Here is my c program:

int main(int argc, char *argv[]){
    char cmd[0xFF];
    // For me, argv[1] is the location of the file that is being opened.  I'm not sure if this is different on other OSes
    snprintf(cmd,sizeof cmd,"python YOUR_PYTHON_SCRIPT_HERE.py -a %s", argv[1]);
    system(cmd);
    return 0;
}

I then compiled the c program and set that as the default application for the file extension.
Then, in the python script YOUR_PYTHON_SCRIPT_HERE.py, I receive the argument like this:

import sys
assert len(sys.argv) > 2 # Breaks if you call the script without the arguments
theFile = " ".join(sys.argv[2:]) # What the c program gives us 
print(theFile) # Print it out to prove that it works

theFile will contain the location of the file that is being opened
Get the contents of the file by using:

with open(theFile,"r") as f:
    fileContents = f.read()

Answer 3

By example, here's a universal solution I wrote for: 1) opening a Windows desktop link (*.URL) that's been copied to a Linux box. Or 2) opening a Linux .Desktop link that's been copied to a Windows box.

Here's the Python script that handles both cases:

# UseDesktopLink.py
import sys
import webbrowser
script, filename = sys.argv
file_object = open(filename,'r')
for line in file_object:
    if line[0:4]=="URL=":
        url=line[4:]
        webbrowser.open_new(url)
file_object.close()

On Windows, use Scott H's method (via a bat file) to handle the association.

On Linux, right-click a Windows URL file. Choose Properties, and Open With. Click Add to add a new application. Then at the bottom of the "Add Application" window, click "Use a custom command". Then browse to the UseDesktopLink.py file and click Open. But before you click Add, in the textbox below "Use a custom command", put "python " before the filename (without the quotes). Then click Add and Close.

Hope that helps.

Answer 4

1. Find any file of type foo
2. right-click -> Get Info or Click on the file icon,then click Get info or click on the file and hit Command+I
3. In the Open With pane that shows up, select the path to the python binary
4. Once selected, You can click the change All button
5. It'll ask for confirmation, just say continue

Answer 5

Mac OS X

On Mac OS X you can use Automator to create an application that calls your python app and passes the input file path as a string argument. In the application workflow wizard, add action "Run Shell Script", select Pass input: as as arguments, and in the text box add:

python /path/to/my/app/myapp.py "$@"

The "$@" passes along whatever arguments were in the input (aka the selected file) as strings. As long as your script is set up to deal with the input (sys.argv) as a list of strings (the first one being the python app path), then it will work.

When you save that Automator workflow, it is treated by OS X like any other app, and you can set that app as the default for files of type "*.foo". To associate "*.foo" with that app, right click a .foo file, Get Info, Open with: Other..., choose the app you created in Automator, then click the Change All... button.

Windows

A similar but hopefully less-involved approach might work in Windows. You could probably create a batch file (.bat) with the following:

python C:\path\to\my\app\myapp.py %*

The %* expands to all arguments.

As long as you can associate a file extension with that batch file, then you could do that, and that's your solution. However, I haven't tried this Windows solution, so take it with a grain of salt. The Mac solution, on the other hand, I have tested.