Merge branch 'jpype-imports-context-manager' into 'master'

provide import system access through context manager

See merge request !32

CHANGELOG.md

 # Changelog
 
+## [2.4.1] - 20.05.2020
+### Changed 
+- add support for the JPype import system (`Manager.imports()`)
+
 ## [2.2.5] - 21.10.2019
 ### Changed 
 - avoid downloading jars at every execution
\ No newline at end of file

README.md

@@ -58,12 +58,21 @@ Finally, from your code, you can start a JVM with the complete list of jars
 using:
 
 ```python
->>> mgr = cmmnbuild_dep_manager.Manager()
->>> jpype = mgr.start_jpype_jvm()
+mgr = cmmnbuild_dep_manager.Manager()
+jpype = mgr.start_jpype_jvm()
 ```
 
 At this stage, JPype is ready to use.
 
+To enable the JPype (>= 0.7) import system, you can use the `imports()` context manager:
+```python
+mgr = cmmnbuild_dep_manager.Manager()
+with mgr.imports():
+    from cern.some.service import Service
+    # ...
+```
+
+
 ## Advanced usage
 
 ### Re-downloading jars
@@ -84,8 +93,8 @@ Helper functions are provided to inspect the classes in the downloaded jars.
 Provides a listing of all classes contained within the jars:
 
 ```python
->>> mgr = cmmnbuild_dep_manager.Manager()
->>> mgr.class_list()
+mgr = cmmnbuild_dep_manager.Manager()
+mgr.class_list()
 ['cern.accsoft.cals.extr.client.commandline.CommandLineException',
  'cern.accsoft.cals.extr.client.commandline.CommandLineServiceBuilder',
  'cern.accsoft.cals.extr.client.commandline.CommandMethod',
@@ -98,8 +107,8 @@ Provides a listing of all classes contained within the jars:
 Search for any class by name:
 
 ```python
->>> mgr = cmmnbuild_dep_manager.Manager()
->>> mgr.class_search('ServiceBuilder')
+mgr = cmmnbuild_dep_manager.Manager()
+mgr.class_search('ServiceBuilder')
 ['cern.accsoft.cals.extr.client.commandline.CommandLineServiceBuilder',
  'cern.accsoft.cals.extr.client.service.ServiceBuilder',
  'cern.cmw.rda3.client.service.ClientServiceBuilder',
@@ -111,15 +120,15 @@ Search for any class by name:
 Provide a pasteable example of how to use a specific class from Python:
 
 ```python
->>> mgr = cmmnbuild_dep_manager.Manager()
->>> mgr.class_hints('cern.accsoft.cals.extr.client.service.ServiceBuilder')
+mgr = cmmnbuild_dep_manager.Manager()
+mgr.class_hints('cern.accsoft.cals.extr.client.service.ServiceBuilder')
 cern = jpype.JPackage('cern')
 ServiceBuilder = cern.accsoft.cals.extr.client.service.ServiceBuilder
 
->>> jpype = mgr.start_jpype_jvm()
->>> cern = jpype.JPackage('cern')
->>> ServiceBuilder = cern.accsoft.cals.extr.client.service.ServiceBuilder
->>> ServiceBuilder
+jpype = mgr.start_jpype_jvm()
+cern = jpype.JPackage('cern')
+ServiceBuilder = cern.accsoft.cals.extr.client.service.ServiceBuilder
+ServiceBuilder
 jpype._jclass.cern.accsoft.cals.extr.client.service.ServiceBuilder
 ```
 
@@ -143,8 +152,8 @@ pyjapc
 Which is equivalent to the following Python code:
 
 ```python
->>> mgr = cmmnbuild_dep_manager.Manager()
->>> mgr.register('pytimber', 'pyjapc')
+mgr = cmmnbuild_dep_manager.Manager()
+mgr.register('pytimber', 'pyjapc')
 ('pytimber', 'pyjapc')
 ```
 
@@ -158,8 +167,8 @@ cmmnbuild_dep_manager manager directly. For example, manual installation of
 a package can be achieved with:
 
 ```python
->>> mgr = cmmnbuild_dep_manager.Manager()
->>> mgr.install('pyjapc')
+mgr = cmmnbuild_dep_manager.Manager()
+mgr.install('pyjapc')
 ```
 
 The `install()` function registers the package and resolves the dependencies
@@ -193,8 +202,8 @@ class PyJapc:
 Then the user executing:
 
 ```python
->>> import pyjapc
->>> japc = pyjapc.PyJapc()
+import pyjapc
+japc = pyjapc.PyJapc()
 ```
 
 will cause the jars to be downloaded if they aren't already existing on disk

cmmnbuild_dep_manager/cmmnbuild_dep_manager.py

@@ -79,6 +79,27 @@ class Manager(object):
         yield
         self.log.setLevel(orig_level)
 
+    @contextmanager
+    def imports(self):
+        '''Run a piece of code with the access to the Java universe through JPype imports.
+        When the context ends, the original python import behavior is restored.
+        '''
+        import sys
+        import importlib
+        old_sys_meta_path = list(sys.meta_path)
+        old_modules = set(sys.modules.keys())
+        import jpype
+        if not jpype.isJVMStarted():
+            self.start_jpype_jvm()
+        import jpype.imports
+        jpype.imports.registerDomain("cern")
+        yield jpype
+        sys.meta_path = old_sys_meta_path
+        added_modules = set(sys.modules.keys()) - old_modules
+        for mod in added_modules:
+            del sys.modules[mod]
+        importlib.invalidate_caches()
+
     def help(self, method='__init__'):
         '''Print the docstring for a method'''
         print(getattr(self, method).__doc__)