Red Hat ENTERPRISE LINUX 4 - DEVELOPER TOOLS GUIDE, Руководство пользователя

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Chapter 14. Using gdb with Different Languages 121
will tell gdb to send the -hash message to object and print the result. Also an additional command
has been added,
print-object
or
po
for short, which is meant to print the description of an object.
However, this command may only work with certain Objective-C libraries that have a particular hook
function, called
_NSPrintForDebugger
defined.
14.4.3. Modula-2
The extensions made to gdb to support Modula-2 only support output from the gnu Modula-2 compiler
(which is currently being developed). Other Modula-2 compilers are not currently supported, and
attempting to debug executables produced by them is most likely to give an error as gdb reads in the
executable’s symbol table.
14.4.3.1. Operators
Operators must be defined on values of specific types. For instance,
+
is defined on numbers, but
not on structures. Operators are often defined on groups of types. For the purposes of Modula-2, the
following definitions hold:
•
Integral types consist of
INTEGER
,
CARDINAL
, and their subranges.
•
Character types consist of
CHAR
and its subranges.
•
Floating-point types consist of
REAL
.
•
Pointer types consist of anything declared as
POINTER TO
type
.
•
Scalar types consist of all of the above.
•
Set types consist of
SET
and
BITSET
types.
•
Boolean types consist of
BOOLEAN
.
The following operators are supported, and appear in order of increasing precedence:
,
Function argument or array index separator.
:=
Assignment. The value of
var := value
is
value
.
6
,
7
Less than, greater than on integral, floating-point, or enumerated types.
6
=,
7
=
Less than or equal to, greater than or equal to on integral, floating-point and enumerated types,
or set inclusion on set types. Same precedence as
6
.
=,
6
7
, #
Equality and two ways of expressing inequality, valid on scalar types. Same precedence as
6
.
In gdb scripts, only
6
7
is available for inequality, since
#
conflicts with the script comment
character.
IN
Set membership. Defined on set types and the types of their members. Same precedence as
6
.