CONVERT

How to convert code to MICO 2.2.7
---------------------------------

MICO 2.2.7 includes some major changes for CORBA compliance that require
changes in user code. The changes are related to:
- CORBA compliant exception handling
- Any insertion and extraction operators
- variable length inout parameters


1. Exception handling
---------------------

MICO now supports CORBA compliant exception handling. You can still
revert to old style exception handling by configuring MICO with
--disable-std-eh:

  ./configure --disable-std-eh

However, we strongly recommend that you change your code to use CORBA
compliant exception handling. See section "Exceptions" in the
documentation for details.

The easiest way to convert code that uses old style exception handling
code to CORBA compliant exception handling is to change each occurence of

  } catch (XXX_var &yyy) {

to

  } catch (XXX_catch &yyy) {

This code will work both with old style exception handling and CORBA
compliant exception handling.

There is a script (mico/admin/ehconvert.sh) that does this conversion
automatically. It takes a list of files to convert on the command line:

  ./ehconvert.sh foo.cc bar.cc


2. Any insertion and extraction operators
-----------------------------------------

When using >>= operators to extract

  - strings
  - wide strings
  - object references
  - typecodes

from an Any ownership of the extracted value is maintained by the Any,
i.e. no copy is returned (as in MICO before 2.2.7). The user must
not free the extracted value. Note that the extracted value is only
valid as long as the Any (the value was extracted from) is not changed
or destroyed. Here are some examples:

  CORBA::Any a;

  // wrong, String_var will free extracted value
  CORBA::String_var s;
  a >>= s;

  // wrong, must not free extrated value
  char *s;
  a >>= s;
  ...
  CORBA::string_free (s);

  // ok
  char *s;
  a >>= s;
  // do not free 's' ...

Or for object references assuming there is an interface I:

  CORBA::Any a;

  // wrong
  I_var i;
  a >>= i;

  // wrong
  I_ptr i;
  a >>= i;
  ...
  CORBA::release (i);

  // ok
  I_ptr i;
  a >>= i;
  // do not free 'i'

Please refer to section "Untyped Values" in the documentation.

Furthermore the return type of all <<= operators is now void (instead
of CORBA::Boolean as in MICO before 2.2.7). Existing code that checks
the return value has to be changed accordingly. Here is an example:

  CORBA::Any a;
  CORBA::Long l;

  if (a <<= l) {
    // something 1
  } else {
    // something 2
  }

should be changed to:

  CORBA::Any a;
  CORBA::Long l;

  a <<= l;
  // something 1


3. Variable length inout parameters
-----------------------------------

If you want to change the value of a variable length inout parameter
in a method implementation you have to free the old value first, i.e.
the old value is no longer automatically freed (as in MICO before 2.2.7).
Variable length inout parameters are:

  - string
  - wide string
  - object references
  - valuetypes

Here is an example:

  // IDL
  interface I {
    void m (inout string s, inout I i);
  }

  // C++

  // wrong, must free old values
  void I_impl::m (char *&s, I_ptr &i) {
    s = CORBA::string_dup ("foo");
    i = new I_impl;
  }

  // ok
  void I_impl::m (char *&s, I_ptr &i) {
    CORBA::string_free (s);
    s = CORBA::string_dup ("foo");
    CORBA::release (i);
    i = new I_impl;
  }

Note that this applies only to inout parameters, not to out parameters.