Under which conditions does the Message Compiler generate setFieldValueAsString() support?
Henning P
Hello everybody,
I have a slightly tricky question about the behaviour of the Compiler for *.msg files. I came across this issue during the work with the Java Extensions. This post refers to OMNeT 5.0 and Inet 3.4.0. However, I assume that the observed behaviour is more general.
My question is: under which conditions does the Message Compiler generate setFieldValueAsString() support for a field? Only if a corresponding method in the class cClassDescriptor exists for the type this specific field (e.g., string2long() if the field is of type long)? This there a way to convince the Message Compiler to support setFieldValueAsString() for complex types (e.g., MyClass).
Actually, I am wondering that a field having a complex type (e.g., MyClass) cannot be set via setFieldValueAsString(). This is also the case, if a string constructor exists for MyClass and hence the conversion from string is trivial.
Example:
For the following file test.msg, the Message Compiler generates a method getFieldValueAsString() that supports all fields (testInt and testMacAddress) and a method setFieldValueAsString() that supports only the ones having primitive types (testInt). (Note: I know that I can manually edit the method setFieldValueAsString() in Test_m.cc, which actually works. However, I would like to have a cleaner implementation and not manually modify a generated file).
Test.msg:
cplusplus {{
#include "inet/linklayer/common/MACAddress.h"
}}
class noncobject MACAddress;
namespace inet;
message Test{
int testInt;
MACAddress testMacAddress;
}
Test_m.cc (generated from Test.msg by the Message Compiler):
…
std::string TestDescriptor::getFieldValueAsString(void *object, int field, int i) const
{
omnetpp::cClassDescriptor *basedesc = getBaseClassDescriptor();
if (basedesc) {
if (field < basedesc->getFieldCount())
return basedesc->getFieldValueAsString(object,field,i);
field -= basedesc->getFieldCount();
}
Test *pp = (Test *)object; (void)pp;
switch (field) {
case 0: return long2string(pp->getTestInt());
case 1: {std::stringstream out; out << pp->getTestMacAddress(); return out.str();}
default: return "";
}
}
bool TestDescriptor::setFieldValueAsString(void *object, int field, int i, const char *value) const
{
omnetpp::cClassDescriptor *basedesc = getBaseClassDescriptor();
if (basedesc) {
if (field < basedesc->getFieldCount())
return basedesc->setFieldValueAsString(object,field,i,value);
field -= basedesc->getFieldCount();
}
Test *pp = (Test *)object; (void)pp;
switch (field) {
case 0: pp->setTestInt(string2long(value)); return true;
default: return false;
}
}
…
Regards
Henning
Attila Török
Judging from a quick look at the source of msgc (src/nedxml/msgcodegenerator.cc), I believe the field has to have the @editable property, and maybe @fromString(...) as well.
Attila
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Henning P
Hi,
Actually, the answer to my question is that there are two solutions to get the
possibility to the field via setFieldValueAsString().
Solution 1: There is a conversion method (e.g., string2long() if the field is of type long) in the class cClassDescriptor.
Solution 2: The @fromString(...) property can be used to link towards a method for the conversion (e.g., the string constructor). (e.g.: MACAddress testMacAddress @editable() @fromstring(inet::MACAddress($));)
Many thanks to Attila for the hints to get towards these solutions!
Regards
Henning
PS: sorry for the late reply but we wanted to examine this in detail before.
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