context: Provide global instance

This will avoid the increasingly ugly pushing around of a context
instance as parameter to various methods/functions. Everyone can now
simply call get_context() after build or shell called
create_global_context().

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

kas/build.py

@@ -24,7 +24,7 @@
 """
 
 import os
-from .context import Context
+from .context import create_global_context
 from .libkas import find_program, run_cmd, kasplugin
 from .libcmds import (Macro, Command, SetupDir, CleanupSSHAgent,
                       SetupSSHAgent, SetupEnviron, SetupRepos,
@@ -71,7 +71,7 @@ class Build:
         if args.cmd != 'build':
             return False
 
-        ctx = Context(args.config, args.target, args.task)
+        ctx = create_global_context(args.config, args.target, args.task)
 
         macro = Macro()
 

kas/context.py

@@ -48,6 +48,25 @@ except ImportError:
         # pylint: disable=deprecated-method
         return platform.dist()[0]
 
+__context__ = None
+
+
+def create_global_context(config_filename, bitbake_target, bitbake_task):
+    """
+        Create global context as singleton.
+    """
+    # pylint: disable=global-statement
+    global __context__
+    __context__ = Context(config_filename, bitbake_target, bitbake_task)
+    return __context__
+
+
+def get_context():
+    """
+        Return singleton global context.
+    """
+    return __context__
+
 
 # pylint: disable=too-many-instance-attributes
 class Context:

kas/shell.py

@@ -27,7 +27,7 @@
 import subprocess
 import os
 from .libkas import kasplugin
-from .context import Context
+from .context import create_global_context
 from .libcmds import (Macro, Command, SetupDir, SetupEnviron,
                       WriteBBConfig, SetupHome, ReposApplyPatches,
                       CleanupSSHAgent, SetupSSHAgent, SetupRepos)
@@ -75,7 +75,7 @@ class Shell:
         if args.cmd != 'shell':
             return False
 
-        ctx = Context(args.config, args.target, None)
+        ctx = create_global_context(args.config, args.target, None)
 
         macro = Macro()