Re: How to define operator "const char *" of enumerated type defined inside a class

From:
"Bill Davy" <Bill@XchelSys.co.uk>
Newsgroups:
comp.lang.c++
Date:
Wed, 24 Sep 2008 12:48:40 +0100
Message-ID:
<6junooF50pl4U1@mid.individual.net>

I want to be able to write (const char*)v where v is an item of type
Class::ToolTypeT where ToolTypeT is an enumeration and I've tried
everything that looks sensible. There's an ugly solution, but surely this
is
possible?


"Sam" <sam@email-scan.com> wrote in message
news:cone.1222254608.28545.7466.500@commodore.email-scan.com...

You can't really do this with merely an enum. You can, however, define a
class that, essentially, acts like an enum.

class Class {

public:

 static const int a=0;
 static const int b=1;
 static const int c=2;

 class ToolTypeT {
  int v;

 public:
  ToolTypeT(int i): v(i) {}

  ToolType &operator=(int i) { v=i; return *this; }

  operator int() const { return v; }

  operator const char *();
 };
};

You can use this Class::ToolTypeT pretty much like an enumeration. Class::a,
Class::b, Class::c, etc. are your enumerator values. And, you can supply a
meaningful operator const char *().

And, with a few more tweaks, you can add additional type-safety to the whole
schema.

Bill Davy writes:

That's an interesting approach. Can switch on ToolTypeT which is good. Can
even make a,b,c into an eunumeration (which may help some tools notice if I
have missed one out). And the type conversion is there.

Many thanks,
    Bill

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