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Posted by Daniel Klein on 01/29/08 14:23
On Mon, 28 Jan 2008 18:57:07 -0800 (PST), ZeldorBlat <zeldorblat@gmail.com>
wrote:
>On Jan 28, 8:45 pm, Daniel Klein <dani...@featherbrain.net> wrote:
>> I've got a class that has a couple of methods that can't be 'private' cos
>> they can be called by other classes in the project, but they should not be
>> called by user code, so I've had to make them 'public'. In other languages
>> these methods would have 'friend' visibility.
>>
>> I suspect there is no 'friend' access modifier since php has no concept of a
>> 'module' or 'assembly' (at least none that I am aware of).
>>
>> I'm use to coding in dynamic languages where you use the 'honor system'. For
>> example, in python you indicate this by placing an underscore character in
>> front of the method/function. You also document the method to indicate your
>> intentions. So unless there is a similar php convention, I am more than ok
>> doing it that way.
>>
>> So my question is: What is the php way of doing this?
>>
>> Daniel Klein
>
>None that I'm aware of. If you don't want your user code to call a
>method, then don't call that method :)
>
>Besides, I never liked the whole "friend" concept. Objects should be
>reusable -- which means that it shouldn't matter who is using them.
>If you want to use them from "user code" then go for it. If you want
>to use them from other objects then that's fine, too. You give your
>methods public visibility and everyone can get to them. If you want
>to hide something, make it protected or private.
>
>Why should certain objects be given special access to the internals of
>another class while other not-so-special objects don't get any? If
>you've designed your classes correctly you shouldn't need friends at
>all.
Although Jerry Stuckle answered my question, I feel compelled to respond
here...
I think you misunderstood the issue.
The situation is such that there are several classes that work together (in
..NET terms this would be an 'assembly'). Two of the methods of one of the
classes perform very special (friendly ;-) ) things for the rest of the
classes, so it is ok for those 'other' classes to access those methods as
this is by design. However, it makes no sense whatsoever for code outside of
these classes to use those methods, hence the original request for some sort
of PHP convention to indicate this.
Here is a pseudo-code example which is close to what I'm doing (I've placed
'friend' in front of the appropriate methods for clarity):
class connection {
public function open_connection {}
friend function send_data {}
friend function recv_data {}
public function close_connection {}
}
class resource {
public function open {}
public function read {}
public function write {}
public function close {}
}
All of the 'resource' functions use the 'connection->send_data' and
'connection->recv_data' methods. Any other code using either the 'send' or
'recv' methods have no clue (should not be concerned) what the api is. That
code will simply use the 'open' 'read' 'write' 'close' methods as that is
all 'outside code' needs to know about (ie the 'public api').
The 'send' and 'recv' functions can't be 'private' cos they need to be
accessed from the 'connection' class, and they shouldn't be 'public' cos
outside code should not them directly, but only via the other 'public'
methods.
I am open to suggestions on how to restructure this without having to
duplicate code.
Daniel Klein
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