Dependency inference

documentation/demos/demo_dependency_inference.sh

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+#!/bin/bash
+set -xe
+
+pip install pcs
+pcs activate
+# Create an empty VirtualEnv; point 'base' alias at it; activate it.
+python --version
+# 3.9.10
+python -c "import numpy; print(numpy.random)"
+# Create a new VirtualEnv; pip install numpy into it; run this command in it.
+# stdout: 28.37  <--some random number
+
+pcs list --type Command
+# Identifier    Type      Aliases
+# 3857a         Command   last, 0
+
+pcs list
+# Identifier    Type          Aliases
+# 3857a         Command       last_Command, 0
+# 7b6c0         VirtualEnv    last_VirtualEnv
+# 45abd         VirtualEnv    base
+
+pcs config set default-py 3.8.3  # updates ~/.pcsconfig.yaml
+# Create new empty VirtualEnv with Python 3.8.3; point alias 'base' at it
+python --version  # Creates a new VirtualEnv with Python 3.8.3
+# 3.8.3
+
+virtualenv my_new_venv  # creates a new alias in the local_registry pointing
+                        # to the venv Component that is was currently in-use.
+ls
+# my_new_venv <-- this is a symlink to the venv in the ~/.pcs/cache/ dir
+# other_files_and_folders
+
+pcs list --type VirtualEnv

documentation/demos/import_logging_demo.py

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+import builtins
+import importlib
+import pprint
+import sys
+from collections import defaultdict
+from types import ModuleType
+from graphviz import Digraph
+
+
+class Graph:
+    """Utility class."""
+    def __init__(self):
+        self.nodes = set()
+        self.edges = defaultdict(set)
+
+
+class ImportLogger:
+    def __enter__(self):
+        self.original_import = builtins.__import__
+        builtins.__import__ = self._import_wrapper
+        self.imports = {}
+        return self
+
+    def __exit__(self, *args):
+        builtins.__import__ = self.original_import
+
+    def log_import(
+        self, name, imported, globals, locals=None, fromlist=(), level=0
+    ):
+        importer_name = globals["__name__"]
+        im_file = imported.__file__ if hasattr(imported, '__file__') else ""
+        self.imports[(importer_name, name)] = (imported, im_file)
+
+    def _import_wrapper(self, name, *args, **kwargs):
+        imported = self.original_import(name, *args, **kwargs)
+        self.log_import(name, imported, *args, **kwargs)
+        return imported
+
+
+class Module:
+    def __init__(self, name: str, version: str = None):
+        self.name = name
+        self._imports: [str, "Module"] = None
+
+    @property
+    def imports(self) -> [str, "Module"]:
+        with ImportLogger() as importer:
+            self.get()
+            self._imports = importer.imports
+        return self._imports
+
+    def get(self) -> ModuleType:
+        return importlib.import_module(self.name)
+
+    def save_dag_file(self, filename):
+        """Save a file representing the DAG associated with this Module."""
+        gv_graph = Digraph(comment=f"Python module import DAG of {self.name}")
+        g = self.generate_dag()  # get back a Graph object
+        for node in g.nodes:
+            gv_graph.node(node)  # Can specify 'shape=oval', etc.
+        for parent, children in g.edges.items():
+            for child in children:
+                gv_graph.edge(parent, child)
+        gv_graph.render(filename, view=True)
+        print(f"Saved graph to {filename}")
+
+    def generate_dag(self):
+        """return a dot representation of the import DAG associated with this
+        Module that will start at this Module and have edges to any Modules
+        that it imports, and the modules they import, etc."""
+        graph = Graph()
+        for child, parent in self._imports.keys():
+            graph.nodes.add(child)
+            graph.nodes.add(parent)
+            graph.edges[child].add(parent)
+        return graph
+
+
+if __name__ == "__main__":
+    if len(sys.argv) > 1:
+        module_name = sys.argv[1]
+    else:
+        print(f"sys.argv: {sys.argv}")
+        exit("Please provide a package name as an arg to this script.")
+    m = Module(module_name)
+    pprint.pprint(m.imports)
+    m.save_dag_file(f"{module_name}_import_dag.gv")