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Thread: PEAR_Callback proposal




PEAR_Callback proposal
user name
2007-01-05 18:47:18
Hi,

Lukas Feiler wrote:
> A couple of days ago I proposed the package
PEAR_Callback;
> see http://pear.php.net/pepr/pepr-proposal-show.php?id=468
> 
> It addresses three major limitations of the callback
pseudo-type:
> - By looking at a callback pseudo-type variable you
>   cannot tell if it really is a callback.
> - The callback pseudo-type does not allow you to
specify
>   arguments at the time you create the callback.
> - There is no way to force a user to pass only callback
>   functions to your API, that meet certain requirements
>   (i.e. accept certain arguments and have a certain
>   return type)

All of these major limitations can be overcome by using the
Command design pattern:
http://e
n.wikipedia.org/wiki/Command_pattern

I don't honestly see the benefit for PEAR in adding a
wrapper around functions 
when all these checks are already available for classes /
objects in PHP5.

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PEAR_Callback proposal
user name
2007-01-05 21:30:52
Hi,

Alexey Borzov wrote:
> 
> Hi,
> 
> Lukas Feiler wrote:
> > A couple of days ago I proposed the package
PEAR_Callback;
> > see http://pear.php.net/pepr/pepr-proposal-show.php?id=468
> > 
> > It addresses three major limitations of the
callback pseudo-type:
> > - By looking at a callback pseudo-type variable
you
> >   cannot tell if it really is a callback.
> > - The callback pseudo-type does not allow you to
specify
> >   arguments at the time you create the callback.
> > - There is no way to force a user to pass only
callback
> >   functions to your API, that meet certain
requirements
> >   (i.e. accept certain arguments and have a
certain
> >   return type)
> 
> All of these major limitations can be overcome by using
the 
> Command design pattern:
> http://e
n.wikipedia.org/wiki/Command_pattern
> 
> I don't honestly see the benefit for PEAR in adding a
wrapper 
> around functions 
> when all these checks are already available for classes
/ 
> objects in PHP5.
> 

PEAR_Callback effectively is a general command pattern
implementation - it
eliminates the need to write a command class for every
callback function a
programmer wants to use.

But I do get your point. After all, OO languages like Java
don't even have
something like call_user_func().

Cheers,
Lukas

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