[PATCH] Fix usage of to_string() for pretty-printers with children

Peter Linss
2017-05-25T02:33:46Z

Currently when using python pretty-printers that have children in the mi interpreter, the value of the variable object will always return “{...}”, this change will return the result of the pretty-printer’s to_string() method if present. If the pretty-printer has children but doesn’t have a to_string() method, then “{...}” will still be returned.

This allows pretty-printers to optionally return a brief summary of the variable in addition to the expanded list of children and makes the behavior under the mi interpreter match that of the regular interpreter.

This fixes bug 11335.

I also removed the dynamic_varobj_has_child_method function as it wasn't doing anything that hadn’t already been done in the varobj_value_get_print_value function and isn’t used elsewhere.

Tested with Eclipse and the libstdc++-v3 pretty-printer as well as custom pretty-printers for an in-house project and SublimeGDB (SublimeGDB required some additional changes to properly support pretty-printers but those are not related to this change).

gdb/ChangeLog:

* varobj.c (varobj_value_get_print_value): Call pretty-printer
to_string method for value if present even when children
method is available.
(dynamic_varobj_has_child_method) Remove unused function.

gdb/doc/ChangeLog:

* gdb.texinfo (Variable Objects, Result): Update description of
value to reflect to_string output.

---
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 9fb70f6d2a..05e5b868ed 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -29444,8 +29444,9 @@ reliable for a dynamic varobj. Instead, you must examine the

@item value
The varobj's scalar value. For a varobj whose type is some sort of
-aggregate (e.g., a @code{struct}), or for a dynamic varobj, this value
-will not be interesting.
+aggregate (e.g., a @code{struct}) this value will not be interesting.
+For a dynamic varobj, this value comes from the Python pretty-printer
+object's @code{to_string} method, if present. @xref{Pretty Printing API}.

@item type
The varobj's type. This is a string representation of the type, as
diff --git a/gdb/varobj.c b/gdb/varobj.c
index 7bd549d45c..925c6318a8 100644
--- a/gdb/varobj.c
+++ b/gdb/varobj.c
@@ -686,21 +686,6 @@ install_dynamic_child (struct varobj *var,
}
}

-#if HAVE_PYTHON
-
-static int
-dynamic_varobj_has_child_method (const struct varobj *var)
-{
- PyObject *printer = var->dynamic->pretty_printer;
-
- if (!gdb_python_initialized)
- return 0;
-
- gdbpy_enter_varobj enter_py (var);
- return PyObject_HasAttr (printer, gdbpy_children_cst);
-}
-#endif
-
/* A factory for creating dynamic varobj's iterators. Returns an
iterator object suitable for iterating over VAR's children. */

@@ -2420,11 +2405,6 @@ varobj_value_get_print_value (struct value *value,

if (value_formatter)
{
- /* First check to see if we have any children at all. If so,
- we simply return {...}. */
- if (dynamic_varobj_has_child_method (var))
- return "{...}";
-
if (PyObject_HasAttr (value_formatter, gdbpy_to_string_cst))
{
struct value *replacement;
@@ -2486,6 +2466,13 @@ varobj_value_get_print_value (struct value *value,
if (replacement)
value = replacement;
}
+ else
+ {
+ /* If we don't have to_string but we have children,
+ we simply return {...}. */
+ if (PyObject_HasAttr (value_formatter, gdbpy_children_cst))
+ return "{...}";
+ }
}
}
#endif

--