Re: How to initialise member variable in template construction

red floyd <>
Wed, 1 Sep 2010 15:11:59 -0700 (PDT)
On Sep 1, 2:55 pm, Angus <> wrote:

On 1 Sep, 22:51, "Francesco S. Carta" <> wrote:

Angus <>, on 01/09/2010 14:43:29, wrote:

I am trying to set the strategy (algorithm) used in a context by
template. Here is my context class (which is incorrectly
template<class TStrategy>
class Context //TStrategy is the algorithm
         TStrategy * strategy_; //knows about StrategyIn=


         void execute() const

The strategies:
class StrategyInterface
         virtual void execute() const = 0; //abstract cla=

ss - interface


//the actual concrete algorithms
class ConcreteStrategyA: public StrategyInterface
         virtual void execute() const
             cout<< "Called ConcreteStrategyA execut=

e method"<< endl;


And I want to do something like this:
Context<ConcreteStrategyA> contextD;

But I need to initialise the context data member properly. how do =


do that?

I'm not sure about "how" you would do that, but I know "where" you
should do that: in a constructor. There is none in the code you posted,=


  FSC - quoted text -

- Show quoted text -

I guess I just need to add this:
Context(){ strategy_ = new TStrategy; }
~Context() { delete strategy_; }

Could I do it without using the heap?

Not if you store a pointer, You defined stategy_ as a TStrategy*.

You could go with a straight-up strategy member.

template <class TStrategy>
class Context //TStrategy is the algorithm
        TStrategy strategy_; //knows about StrategyInterface

        void execute() const


Then there's no allocation needed, and strategy_ is automatically

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