gnatdbg.setup: by default, register pretty-printers globally

Change-Id: Ibb632f5a3de4e0708db94850b2b74806bc036247
For GitHub issue AdaCore#2
no-tn-check

Author: pmderodat

gnatdbg/__init__.py

@@ -1,4 +1,5 @@
 import gdb
+import gdb.printing
 
 
 from gnatdbg.lists import (
@@ -18,17 +19,16 @@
 from gnatdbg.utils import register_pretty_printers
 
 
-setup_done = False
-printers = None
+_setup_done = False
+_printers = None
 
 
-def setup():
-    global setup_done
-    global printers
-    if setup_done:
-        return
-
-    printers = GDBPrettyPrinters('gnat-runtime')
+def create_printers(name='gnat-runtime'):
+    """
+    Instantiate GDBPrettyPrinters with the given name and register all
+    pretty-printers for the GNAT runtime in it. Return this instance.
+    """
+    printers = GDBPrettyPrinters(name)
 
     for printer in [
         DoublyLinkedListPrinter,
@@ -52,10 +52,43 @@ def setup():
     ]:
         printers.append(printer)
 
-    # Registers our printers only for objfiles that are Ada main entry points.
-    def objfile_filter(objfile):
-        adainit = gdb.lookup_global_symbol('adainit' or '_adainit')
-        return adainit is not None and adainit.symtab.objfile == objfile
-    register_pretty_printers(printers, objfile_filter)
+    return printers
+
+
+def setup(name='gnat-runtime', globally=True):
+    """
+    Instantiate pretty-printers for the GNAT runtime with the given name and
+    register them.
+
+    If `globally` is true, just register the pretty-printers globally. This is
+    the most simple way to make them work.
+
+    If `globally is false, only register them in objfiles that define the
+    'adainit' symbol. On one hande, this will not make them work on shared
+    objects, but on the other hand this will avoid GDB the cost of looking them
+    up in objfiles that don't contain Ada. You can see this as an unsound
+    optimization.
+
+    This function does its work the first time it is called, but then does
+    nothing if it's called afterwards.
+    """
+    global _setup_done
+    global _printers
+    if _setup_done:
+        return
+
+    _printers = create_printers(name)
+
+    if globally:
+        gdb.printing.register_pretty_printer(None, _printers)
+
+    else:
+        # Registers our printers only for objfiles that are Ada main entry
+        # points.
+        def objfile_filter(objfile):
+            adainit = gdb.lookup_global_symbol('adainit' or '_adainit')
+            return adainit is not None and adainit.symtab.objfile == objfile
+
+        register_pretty_printers(_printers, objfile_filter)
 
-    setup_done = True
+    _setup_done = True

gnatdbg/utils.py

@@ -1,4 +1,5 @@
 import gdb
+import gdb.printing
 
 
 gdb_code_names = {
@@ -22,7 +23,7 @@ def register_pretty_printers(printers, objfile_filter=lambda objfile: True):
 
     def register(objfile):
         if objfile_filter(objfile):
-            objfile.pretty_printers.append(printers)
+            gdb.printing.register_pretty_printer(objfile, printers)
 
     # Give a chance to register pretty-printers for all objfiles already
     # loaded...