Make installations into the base env work

Look at $CONDA_PREFIX first if no name or prefix is given. If that
is not set, only then default to sys.prefix.

README.rst

@@ -8,21 +8,28 @@ A command-line utility to plot Conda dependency graphs.
 Installation
 ============
 
-It is recommended to install ``conda-depgraph`` in its own environment:
+``conda-depgraph`` can be installed as follows:
 
 .. code-block:: console
 
-   $ conda create -n depgraph -c omegacen conda-depgraph
+   $ conda install -c omegacen conda-depgraph
 
-Installing it in the ``base`` environment will work, but then you'll have to
-be sure that ``java`` is available in ``$PATH``.
+It can either be installed into its own conda environment, or into the base
+environment.
+
+Installing it in the base environment has the benefit that the
+``conda depgraph`` command is available in all other environments. However,
+you will have to make sure that ``java`` is available on ``$PATH``.
+
+Installing it in its own environment automatically ensures it can find ``java``,
+but then you will have to activate that environment before you can run
+``conda depgraph``.
 
 
 Usage
 =====
 
-After installation and activation of the environment, a new Conda command is
-available:
+After installation a new Conda command is available:
 
 .. code-block:: console
 
@@ -35,9 +42,9 @@ available:
                     [inout [--distance=<DISTANCE>] <PACKAGE>]
 
 ``depgraph`` can  plot dependency graphs from either cached repository data,
-or from an existing Conda environment. If the target environment is not
-specified via either ``--name`` or ``--prefix``, the current environment is
-used.
+or from an existing Conda environment. The latter is the default behaviour. If
+the target environment is not specified via either ``--name`` or ``--prefix``,
+the current environment is used.
 
 The subcommands (``in``, ``out``, ``inout``) restrict the output to a subgraph
 of the full dependency graph of the environment. They can be arbitrarily nested.
@@ -50,7 +57,7 @@ The direct dependencies of conda:
 
 .. code-block:: console
 
-   $ conda depgraph --name=base outgraph --distance=1 conda
+   $ conda depgraph --name=base out --distance=1 conda
 
 ::
 
@@ -80,7 +87,7 @@ The immediate neighborhood of sqlite:
 
 .. code-block:: console
 
-   $ conda depgraph --name=base inoutgraph --distance==1 sqlite
+   $ conda depgraph --name=base inout --distance==1 sqlite
 
 ::
 

conda-recipe/meta.yaml

@@ -1,6 +1,6 @@
 package:
   name: conda-depgraph
-  version: 1.0.0
+  version: 1.0.1
 
 about:
   home: https://github.com/omegacen/conda-depgraph

src/conda_depgraph/__init__.py

@@ -1 +1 @@
-__version__ = '1.0.0'
+__version__ = '1.0.1'

src/conda_depgraph/cli.py

@@ -1,11 +1,11 @@
 import functools
-import sys
 
 import click
 from asciinet import graph_to_ascii
 
 from . import algorithms
 from . import conda_facade
+from . import exceptions
 
 
 @click.group(chain=True, invoke_without_command=True)
@@ -30,13 +30,10 @@ def main(*_, **__):
 def process_subcommands(subcommands, from_where, prefix, name, output):
 
     if from_where == 'env':
-        if name is not None:
-            prefix = conda_facade.locate_prefix_by_name(name)
-            if prefix is None:
-                msg = f"Could not find Conda environment '{name}'."
-                raise click.BadParameter(msg)
-        if prefix is None:
-            prefix = sys.prefix
+        try:
+            prefix = conda_facade.locate_prefix(name, prefix)
+        except exceptions.DepgraphValueError as e:
+            raise click.BadParameter(e.args)
         g = conda_facade.env_graph(prefix)
     else:
         g = conda_facade.channelcache_graph()

src/conda_depgraph/conda_facade.py

@@ -1,11 +1,22 @@
 import json
 import os
+import pathlib
 import subprocess
-from pathlib import Path
+import sys
 
 import conda
 import conda.exports
-from networkx import DiGraph
+import networkx
+
+from . import exceptions
+
+
+def locate_prefix(name, prefix):
+    if name is not None:
+        prefix = locate_prefix_by_name(name)
+    if prefix is None:
+        prefix = os.environ.get('CONDA_PREFIX', sys.prefix)
+    return prefix
 
 
 def locate_prefix_by_name(name):
@@ -25,13 +36,14 @@ def locate_prefix_by_name(name):
                 name=name, envs_dirs=info['envs_dirs']
             )
         except conda.exceptions.EnvironmentNameNotFound:
-            prefix = None
+            msg = f"Could not find Conda environment '{name}'."
+            raise exceptions.DepgraphValueError(msg)
     return prefix
 
 
 def channelcache_graph():
     prefix = _conda_execute('info', '--base')
-    cache_dir = Path(prefix) / 'pkgs' / 'cache'
+    cache_dir = pathlib.Path(prefix) / 'pkgs' / 'cache'
 
     def package_data():
         for cache_file in cache_dir.glob('*.json'):
@@ -53,7 +65,7 @@ def _conda_execute(*args):
 
 
 def _package_datas_to_graph(datas):
-    g = DiGraph()
+    g = networkx.DiGraph()
     for data in datas:
         for p in data.values():
             n = p['name']

src/conda_depgraph/exceptions.py

@@ -0,0 +1,2 @@
+class DepgraphValueError(ValueError):
+    pass