add script to install a suitable version of Python

Author: Magne Hov

README.md

@@ -21,14 +21,22 @@ and start UDB while sourcing the `libpython.gdb` file from the same directory
 $ udb --ex "source ./libpython.gdb"
 ```
 
-The version of the `libpython.py` library must generally match the version of Python you want to
-debug. These extensions are built around the 3.10 version of the `libpython.py` library.
+The supported version of Python is currently cpython 3.10. The interpreter must have been compiled with full debug information (`-g3`) and without cpython's "computed gotos" feature.
+
+You can use the `./setup-python` script to install a suitable version of Python with `pyenv`:
+
+```
+$ source ./setup-python
+$ python --version
+Python 3.10.15
+```
 
 ### Usage
 
 Use the following commands to inspect Python state:
 
 - `py-print` (`pp`) to print Python objects
+- `py-eval` (`pe`) to evaluate Python expressions
 - `py-list` to list Python source code
 - `py-bt` to show Python backtrace
 - `py-locals` to show local Python variables
@@ -50,7 +58,7 @@ The `py-last-attr` command takes an optional argument to specify which attribute
 
 ---
 
-Switch to the Python layout in TUI mode to get a better overview of your program. This layout automatically shows the output from `py-list`, `py-dis`, `py-locals` and `py-bt`:
+Switch to the Python layout in TUI mode to get a better overview of your program.
 
 ```
 > layout python

setup-python

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+# Ensure that pyenv is installed
+
+PYENV_ROOT="$HOME/.local/share/undo/pyenv"
+if [ ! -d "$PYENV_ROOT" ]; then
+    echo "Installing pyenv"
+    git clone https://github.com/pyenv/pyenv.git "$PYENV_ROOT"
+fi
+
+# Ensure an appropriate Python version is installed
+
+PY_VERSION="3.10.15"
+# For optimal debug information we set `-g3 -Og`.
+CONFIGURE_OPTS="--with-computed-gotos=no" \
+PYTHON_CFLAGS="-g3 -Og" \
+             $PYENV_ROOT/bin/pyenv install \
+             --keep \
+             --verbose \
+             --skip-existing \
+             $PY_VERSION
+
+
+# Make the python version available in the current shell
+export PATH="$PYENV_ROOT/versions/$PY_VERSION/bin:$PATH"