Using the Python Module — Eggdrop 1.10.1rc2 documentation

Eggdrop 1.10.1rc2 documentation

# Using the Python Module

In Eggdrop 1.10.0, Eggdrop was shipped with a Python module that, similar to the existing core Tcl capability, allows Eggdrop to run python scripts.

## System Requirements

Similar to Tcl requirements, Eggdrop requires both python and python development libraries to be installed on the host machine. On Debian/Ubuntu machines, this requires the packages python-dev AND python-is-python3 to be installed. The python-is-python3 updates symlinks on the host system that allow Eggdrop to find it.

The minimum supported Python version is 3.8 and we do require the Global Interpreter Lock for thread safety, even if you use latest Python.

## Loading Python

Put this line into your Eggdrop configuration file to load the python module:

    loadmodule python

To load a python script from your config file, place the .py file in the scripts/ folder and add the following line to your config:

    pysource scripts/myscript.py

If you need to install dependencies we recommend using virtual environments, see https://docs.python.org/3/library/venv.html for more details.

To create the virtual environment in a hidden directory called .venv (only necessary once):

    cd eggdrop && python3 -m venv .venv

To install a python package in the above .venv directory (in this example, the requests package):

    cd eggdrop && source .venv/bin/activate && pip install requests

Starting eggdrop with activated venv (must be run every time for proper functionality):

    cd eggdrop && source .venv/bin/activate && ./eggdrop

You always need to start Eggdrop with the activated venv to set the necessary environment variables.

## Reloading Python Scripts

Unfortunately, reloading python scripts with rehash like Tcl scripts is currently unsupported. Scripts can unbind their existing binds and re-bind them on being loaded again (see the bind section). For now, you should restart your bot when the Python scripts change.

You can (should?) also write scripts that manually unload their binds upon a reshash, example code looks like this:

    # Create a list to track the join binds
    if 'JOIN_BINDS' in globals():
      for joinbind in JOIN_BINDS:
        joinbind.unbind()
      del JOIN_BINDS

    JOIN_BINDS = list()

    <...>

    # Create the binds in the script like this
    JOIN_BINDS.append(bind("join", "*", "*", joinGreetUser))
    JOIN_BINDS.append(bind("join", "o", "*", joinGreetOp))

## Multithreading and async

`pysource` loads a Python script in the main Eggdrop thread but is free to use both async Python and threads.

## Eggdrop Python Commands

The Python module is built to use the existing core Tcl commands integrated into Eggdrop via the `eggdrop.tcl` module. To call an existing Tcl command from Python, you can either load the entire catalog by running `import eggdrop.tcl`, or be more specific by `from eggdrop.tcl import putserv, putlog, chanlist`, etc.

Arguments to the Tcl functions are automatically converted as follows:

- `None` is converted to an empty Tcl object (the empty string, `""`)

- `List` and `Tuple` is converted to a `Tcl list`

- `Dict` is converted to a `Tcl dictionary`

- Everything else is converted to a string using the str() method

Return values from Tcl functions must be manually converted:

- `""` the empty string is automatically converted to None

- everything else is returned as string

- `Tcl list` as string can be converted to a Python `List` using `parse_tcl_list`

- `Tcl dictionary` as string can be converted to a Python `Dict` using `parse_tcl_list`

### bind <arguments>

An important difference to note is that Eggdrop Python has its own `bind` command implemented. You will generally want to create binds using the Python `bind` command and not import bind from eggdrop.tcl because a Python bind will call a Python function, whereas using the Tcl bind will call a Tcl function (not one from the script you are writing).

The python version of the bind command is used to create a bind that triggers a python function. The python bind takes the same arguments as the Tcl binds, but here each argument is passed individually. For example, a bind that would look like `bind pub * !foo myproc` in Tcl is written as `bind("pub", "*", "!foo", myproc)`. For more information on Eggsrop bind argument syntax please see Bind Types. The eggdrop.tcl.bind command should not be used as it will attempt to call a Tcl proc.

The `bind` command returns a PythonBind object that has an `unbind` method:

    x = bind("pub", "*", "!foo", myproc)
    x.unbind()

### parse_tcl_list <string>

When a python script calls a Tcl command that returns a list via the eggdrop.tcl module, the return value will be a Tcl-formatted list- also simply known as a string. The `parse_tcl_list` command will convert the Tcl-formatted list into a Python list, which can then freely be used within the Python script.

### parse_tcl_dict <string>

When a python script calls a Tcl command that returns a dict via the eggdrop.tcl module, the return value will be a Tcl-formatted dict- also simply known as a string. The `parse_tcl_dict` command will convert the Tcl-formatted dict into a Python list, which can then freely be used within the Python script.

## Writing an Eggdrop Python script

Some example scripts, complete with documentation, are included with the Python module that ships with Eggdrop (src/mod/python.mod/scripts). These scripts are included to help demonstrate script formatting and usage. The scripts are:

bestfriend.py

  This example script demonstrates how to use the parse_tcl_list() python command to convert a list returned by a Tcl command into a list that is usable by Python.

greet.py

  This is a very basic script that demonstrates how a Python script with binds can be run by Eggdrop.

imdb.py

  This script shows how to use an existing third-party module to extend a Python script, in this case retrieving information from imdb.com.

listtls.py

  This script demonstrates how to use parse-tcl_list() and parse_tcl_dict() to convert a list of dicts provided by Tcl into something that is usable by Python.

urltitle.py

  This script shows how to use an existing third-party module to extend a Python script, in this case using an http parser to collect title information from a provided web page.

### Header section

Python is able to call any Tcl command by importing the `eggdrop` module. For example, to use the `putlog` command in a python script, you would import it as:

    from eggdrop.tcl import putlog

and then call it using:

    putlog("This is a logged message")

An important difference to note is that Eggdrop Python has its own `bind` command implemented. You will generally want to create binds using the Python `bind` command and not import bind from eggdrop.tcl because a Python bind will call a Python function, whereas using the Tcl bind will call a Tcl function (not one from the script you are writing).

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