Validatable

Description

---

To declare classes that has a valid state.

Usage:

• Derive virtually from Validatable class (to avoid the diamond problem), in this way:

  \code
  class YourClass: ELE_CLASS_VALIDATABLE
  ...
  \endcode
  

• If the derived class has copy/moves/assignments, you must call the base class ones, never relying on the intermediate base classes, since virtual inheritance makes that only one copy of Validatable exists in each derived class along the hierarchy (https://stackoverflow.com/questions/44324583/why-must-virtual-base-classes-be-constructed-by-the-most-derived-class)

  \code
  class Yourclass: another class derivative of Validatable 
                   or Validatable itself
  {
      ...
  
      Yourclass(const Yourclass & another):Validatable{another},
                                           "immediate-base"{another}
          { ... }
  
      Yourclass & operator=(const Yourclass & another)
          { if (this != &another) 
            {
              Validatable::operator=(another);
              "immediate-base"::operator=(another);
              ...
            }
            return(*this); }
  };
  \endcode
  

Author

Juan-Antonio Fernandez-Madrigal. http://jafma.net

Date

2018-2019

Copyright

Copyright (c), Individual contributors, see AUTHORS file. This program is free for non-commercial uses. For the rest, contact the AUTHORS. Please include a mention in your programs to the main developer and the web page of the library.

Collaboration diagram for Validatable:

Classes
class	elementa::patterns::Validatable
	Any class derived from this base class gets a "valid"/"invalid" state. More...

Macros
#define	ELE_CLASS_VALIDATABLE   virtual public elementa::patterns::Validatable
	Declare a class derived from Validatable. More...

---

Class Documentation

elementa::patterns::Validatable

class elementa::patterns::Validatable

Any class derived from this base class gets a "valid"/"invalid" state.

The "valid"/"invalid" state can be consulted, being "invalid" by default at the time of object creation if no argument is passed to the Validatable constructor. It can be changed further on becoming a form of the Builder pattern

Derived classes may provide public methods that admit as many args as needed to define the object as valid (it must call the setValid() method here to set the object as valid).

Note

- This class is thread-safe.

- It cannot be implemented with mixins (i.e., a template that inherits from a class to convert it into validatable) because in that case the user's class could not access the valid_ value in the mixin base.

Definition at line 99 of file validatable.h.

Public Member Functions
bool	valid (void) const noexcept
	Public method to be used by users of the derived class. More...
virtual void	checkValid (const std::string &place="") const
	Call this method if an exception is needed when in invalid state. More...
Protected Member Functions
	Validatable (bool initvalid=false) noexcept
	Validatable (const Validatable &oth)
	Derived classes must call this base ctor if they have non-default ones. More...
Validatable &	operator= (const Validatable &oth)
	Derived classes must call this base optor if they have non-default ones. More...
void	setValid (bool defval=true) noexcept
	Derived classes can rewrite their own (hiding this, calling this). More...
void	setInvalid (void) noexcept

Constructor & Destructor Documentation

Validatable() [1/2]

elementa::patterns::Validatable::Validatable ( bool  initvalid = false )

inlineprotectednoexcept

Definition at line 119 of file validatable.h.

Validatable() [2/2]

elementa::patterns::Validatable::Validatable ( const Validatable &  oth )

inlineprotected

Derived classes must call this base ctor if they have non-default ones.

A default copy ctor in derived class automatically calls this one.

Note

No move constructor is provided, only copy one, for the reasons explained in the operator=. This means that Validatable objects are never moved, only copied.

Definition at line 126 of file validatable.h.

Member Function Documentation

valid()

bool elementa::patterns::Validatable::valid ( void  ) const

inlinenoexcept

Public method to be used by users of the derived class.

The derived class itself can use the valid_ member directly, plus any other protected member.

Definition at line 106 of file validatable.h.

Referenced by elementa::base::MultItImpl< Data >::to_string().

checkValid()

virtual void elementa::patterns::Validatable::checkValid ( const std::string &  place = "" ) const

inlinevirtual

Call this method if an exception is needed when in invalid state.

You can also override it if more info in the error is needed.

Definition at line 110 of file validatable.h.

References ELE_CODE_INVSTATE.

operator=()

Validatable & elementa::patterns::Validatable::operator= ( const Validatable &  oth )

inlineprotected

Derived classes must call this base optor if they have non-default ones.

A default assign optor in derived class automatically calls this one.

Note

Move assignment is not provided (it will fall through to a copy-assign) because of the problem of having Validatable accessable through several paths from the derived class: that will produce several calls of the move assignment that leave the Validatable state incorrect. Actually, that produces a compiler warning [-Wmultiple-move-vbase] in g++.

Definition at line 135 of file validatable.h.

Referenced by elementa::adts::graphs::Graph< Vertex, Edge >::eenteringend().

setValid()

void elementa::patterns::Validatable::setValid ( bool  defval = true )

inlineprotectednoexcept

Derived classes can rewrite their own (hiding this, calling this).

Definition at line 144 of file validatable.h.

setInvalid()

void elementa::patterns::Validatable::setInvalid ( void  )

inlineprotectednoexcept

Definition at line 146 of file validatable.h.

Macro Definition Documentation

ELE_CLASS_VALIDATABLE

#define ELE_CLASS_VALIDATABLE   virtual public elementa::patterns::Validatable

#include <elementa/patterns/validatable.h>

Declare a class derived from Validatable.

Definition at line 82 of file validatable.h.