Hello GAP forum
I'm puzzled as to why the following code, which I think should work,
does not. I have reduced the situation to the following:
--------------- start tempo.gap
DeclareCategory("IsMyStruct", IsObject);
StrFamily := NewFamily("MyStructsFamily");
StrType := NewType(StrFamily, IsMyStruct);
DeclareRepresentation("StrRep",
IsComponentObjectRep and IsAttributeStoringRep,
["uno", "dos"]);
CreateStr := function(u,v)
return Objectify(StrType,rec(uno:=u,dos:=v));
end;
InstallMethod(PrintObj,[IsMyStruct],function(S)
Print("uno=",S!.uno,"dos=",S!.dos);
end);
InstallMethod(ViewObj,[IsMyStruct],function(S)
Print("uno=",S!.uno,"dos=",S!.dos);
end);
DeclareAttribute("MyAtr",IsMyStruct);
InstallMethod(MyAtr,[IsMyStruct],function(S) return("hello");
end);
DeclareProperty("MyProp",IsMyStruct);
InstallMethod(MyProp,[IsMyStruct],function(S) return false;
end);
--------------- end tempo.gap
then, after loading in a GAP 4.8.2 session, started with "gap -r":
I get:
gap> Read("tempo.gap");
gap> S:=CreateStr(1,2);
uno=1dos=2
gap> MyAtr(S);
"hello"
gap> KnownAttributesOfObject(S);
[ ]
why is that? However, storing of properties work?
gap> MyProp(S);
false
gap> KnownPropertiesOfObject(S);
[ "MyProp" ]
Thanks in advance for any help.
Rafael
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