Re: [Boost-users] boost::bind issues revisited

Subject: Re: [Boost-users] boost::bind issues revisited
From: Jeff Flinn (Jeffrey.Flinn_at_[hidden])
Date: 2013-04-22 14:23:44

On 4/22/2013 2:13 PM, Jeff Flinn wrote:
> On 4/22/2013 10:29 AM, Littlefield, Tyler wrote:
>> On 4/22/2013 1:07 AM, Nathan Ridge wrote:
>>> ----------------------------------------
>>>> Date: Mon, 22 Apr 2013 00:52:27 -0600
>>>> From: tyler_at_[hidden]
>>>> To: boost-users_at_[hidden]
>>>> Subject: [Boost-users] boost::bind issues revisited
>>>>
>>>> Hello all:
>>>> I'm kind of at a loss here. It looks like ther'es an issue with
>>>> boost::bind somewhere in the mess of 500 templates and 90 screens of
>>>> errors and I don't know enough about the mess to untangle it. Any info
>>>> would be awesome. First, the code:
>>>>
>>>> sgroup->AddEntry(new OlcStringEntry("name", "Sets the name of the
>>>> object", OF_NORMAL,
>>>> boost::bind(&StaticObject::GetName, _1),
>>>> <159> boost::bind(&StaticObject::SetName, _1, _2)));
>>>>
>>>> the 159 I denoted is useful in the errors later.
>>>> Now the rest of the code I'm using:
>>>>
>>>> typedef boost::function<std::string ()> StringGetter;
>>>> typedef boost::function<void (const std::string&)> StringSetter;
>>>>
>>>> class IOlcEntry
>>>> {
>>>> protected:
>>>> std::string _name;
>>>> std::string _help;
>>>> FLAG _flag;
>>>> public:
>>>> IOlcEntry(const std::string &name, const std::string &help, FLAG flag)
>>>> {
>>>> _flag = flag;
>>>> _name = name;
>>>> _help = help;
>>>> }
>>>> ~IOlcEntry() {}
>>>> };
>>>>
>>>> class OlcStringEntry:public IOlcEntry
>>>> {
>>>> protected:
>>>> StringGetter _getter;
>>>> StringSetter _setter;
>>>> public:
>>>> OlcStringEntry(const std::string &name, const std::string &help, FLAG
>>>> flag, const StringGetter getter, const StringSetter setter)
>>>> :IOlcEntry(name, help, flag)
>>>> {
>>>> _setter = setter;
>>>> _getter = getter;
>>>> }
>>>> };
>>> Looks like you are trying to pass "boost::bind(&StaticObject::GetName,
>>> _1)",
>>> which is a 1-argument function object, as the argument for a
>>> parameter of
>>> type "StringGetter", which is a typedef for
>>> "boost::function<std::string ()>",
>>> which is a 0-argument function object.
>>>
>>> You have a similar problem for the setter.
>>>
>>> Perhaps you meant to bind the getter and setter to a specific
>>> instance of
>>> StaticObject? In that case, assuming 'my_instance' is that instance, you
>>> should write:
>>>
>>> boost::bind(&StaticObject::GetName, my_instance)
>>>
>>> and
>>>
>>> boost::bind(&StaticObject::SetName, my_instance, _1)
>>>
>>> and then you'll have function objects that are assignable to
>>> StringGetter
>>> and StringSetter, respectively.
>>>
>>> Regards,
>>> Nate
>>>
>> Hello:
>> I should have been more clear in my original message. Basically what I'm
>> doing is creating a method that I can use to edit objects in game.
>> Rather than attach this to every object, the idea was to set up a
>> collection of editor entries. When I wanted to edit an object I can call
>> these entries on the object. This saves a lot of overhead because rather
>> than there being x*n (where n is the amount of objects) entries, there's
>> just x and each object can call into them when it is edited. I was
>> trying to use _1 etc as placeholders for the "this" pointer; is it
>> possible to do that? I'd like to be able to use any StaticObject I wish
>> with these entries, but I need a way to pass in the this pointer for the
>> object.
>> Thanks,
>
> Then:

(forgot the update typedefs)

typedef boost::function<std::string (const some_base_type*)> StringGetter;
typedef boost::function<void (some_base_type*, const std::string&)> 
StringSetter;

> boost::bind(&StaticObject::GetName, _1)
>
> and
>
> boost::bind(&StaticObject::SetName, _1, _2)
>
> would work for you?

Jeff