I need to make my base class local variable static, so that when extending the class, the subclass will share these variable and use their current values as set by the base class. If I do not make them static, then the base class when extended, will get fresh instance of these variable, losing their original values, which is not what I want.

To do this, one must make the base class variables static

This works, but now I do not know the syntax where to put the type on the variable. 

I can't write   local m::integer::static; nor local m::static::integer;

I could only write local m::static; but this means I lost the ability to have a type on the variable and lost some of the type checking which is nice to have in Maple. From Maple help:

Here is example

restart;

base_class:=module()
  option object;
  local n::static;  #I want this type to ::integer also. But do not know how

  export set_n::static:=proc(_self,n::integer,$)
     _self:-n := n;
  end proc;
  
  export process::static:=proc(_self,$)
    local o;
    o:=Object(sub_class);
    o:-process();
  end proc;
end module;    

sub_class:=module()
   option object(base_class);
   process:=proc(_self,$)
      print("in sub class. _self:-n = ",_self:-n);
   end proc;
end module;

o:=Object(base_class);
o:-set_n(10);
o:-process()


            "in sub class. _self:-n = ", 10

The above is all working OK. I just would like to make n in the base class of type ::integer as well as ::static

Is there a syntax for doing this?

The suggested solution in the answer https://mapleprimes.com/questions/234325-Use-Of-self--Inside-Object-Constructor  worked OK in the setup shown in that question.

But it does not work when putting the constructor inside overload

Here is an example where it works (i.e. by removing the type from _self as suggested in the above answer)

restart;

person:=module()
    option object;
    local name::string:="";

    #notice no _self::person, just _self
    export ModuleCopy::static:= proc( _self, proto::person, the_name::string, $ )            
           name:= the_name;
    end proc;

end module;


p:=Object(person,"me")

The above works. But since I have different constructors, once I put the above inside overload, using the same exact syntax, now the error comes back

restart;

person:=module()
    option object;
    local name::string:="";

    export ModuleCopy::static:= overload( 
    [
       proc( _self, proto::person, the_name::string, $ ) option overload;           
           name:= the_name;
      end proc
    ]);

end module;
             

p:=Object(person,"me")

Error, static procedure `ModuleCopy` refers to non-static local or export `name::string` in surrounding scope

I did not expect that using overload will cause any change to how it behaves. Is this a bug?

Below is worksheet also.

Download OO_version.mw

I noticed in object constructor I had to write  _self:-name  to refer to object own variable called name.  But inside a another proc I can use just name without having to add _self:- to it. It also works when adding _self:-

Is this becuase constructor is special proc, and the object is not yet full constructed?  Here is a MWE

restart;
person:=module()
    option object;
    local name::string:="";

    export ModuleCopy::static:= proc( _self::person, proto::person, the_name::string, $ ) 
            print("Enter  constructor");
           _self:-name:= the_name;

           #Why this fails here, but not in process proc? Is it because of special
           #case since done inside constructor?
           #print(name); 

           print(_self:-name);
    end proc;
 
   export process::static :=proc(_self,$)
     #here both cases work
     print(_self:-name);
     print(name);
   end proc;

end module;

#and now

p:=Object(person,"me")

The above works. But if I uncomment #print(name); inside the constructor, maple gives error

p:=Object(person,"me")
Error, static procedure `ModuleCopy` refers to non-static local or export `name::string` in surrounding scope

But this works with no error

p:-process()

                              "me"
                              "me"

But no such error when doing same thing inside a local static proc inside same module.

Is this special just for the constructor than one must use :-self ? Just wanted to make sure.

Maple 2022.1

To Maple support,

Why when removing symbol a from these equations makes Maple warning go away? This is from a textbook. Attached worksheet. 

restart;
ode:={diff(x__1(t),t)*sin(x__2(t))=x__4(t)*sin(x__3(t))+x__5(t)*cos(x__3(t)),diff(x__2(t),t)= x__4(t)*cos(x__3(t))-x__5(t)*sin(x__3(t)),diff(x__3(t),t)+diff(x__1(t),t)*cos(x__2(t))= 1,diff(x__4(t),t)-(1-B)*a*x__5(t)= sin(x__2(t))*cos(x__3(t)),diff(x__5(t),t)+(1-B)*a*x__4(t)=sin(x__2(t))*sin(x__3(t))};
dsolve(ode)

restart;
ode:={diff(x__1(t),t)*sin(x__2(t))=x__4(t)*sin(x__3(t))+x__5(t)*cos(x__3(t)),diff(x__2(t),t)= x__4(t)*cos(x__3(t))-x__5(t)*sin(x__3(t)),diff(x__3(t),t)+diff(x__1(t),t)*cos(x__2(t))= 1,diff(x__4(t),t)-(1-B)*x__5(t)= sin(x__2(t))*cos(x__3(t)),diff(x__5(t),t)+(1-B)*a*x__4(t)=sin(x__2(t))*sin(x__3(t))};
dsolve(ode)

worksheet attached also

Download warning_may_10_2022.mw

To Maple support:

I was investigating this pde from a different forum.

I noticed that when using an expanded version of the pde, Maple hangs. Without expanding the PDE, Maple gives an answer in 2 seconds. 

Why does expanding the PDE makes a difference? I do not have an earlier version of Maple on my new PC to check if this is a new issue or not.
 

Download hangs_pde.mw