>>>> That is true for PHP variables. isset is basically saying "does this >>>> variable exist", and unset is saying to get rid of it. >>> >>> This is also true for object properties - see magic methods. I don't >>> see >>> why you shouldn't be able to unset them - you can do that with regular >>> properties... So what you imagine would happen if you call >>> unset($foo->property) or isset($foo->property)? >> >> Its not a matter of consistency - Properties, as a cross-language >> concept >> are not meant to work that way. > I tend to disagree. > The need to be consistent inside of PHP has precedence over being > consistent with other languages.
Unfortunately I find that to be one of the major downfalls of PHP. It sometimes disregards defacto standards that are set across the entire industry, which causes a lot of frustration for new programmers. Sometimes the functionality PHP adds by going its own way is worth it, but often it is just a confusing mess. Thats just my opinion though, YMMV. >> You need to think of a property as a set >> of two methods that just have a pretty syntax. Methods cannot be unset, >> and nor should properties be allowed to. isset() should simply tell us >> whether a property with the specified name is part of the class or not. > I think, it really is the other way around. > Properties are meant to give the programmer the illusion that she is just > having a field. > That is abstraction. She does not care about implementation details. > And that is the power of properties. > > isset() and unset() are perfectly fine in that context. > And I do not see a problem to provide the standard semantics for them > automatically, and let the programmer add isset/unset methods to the > property as needed in exactly the same style as get/set. > > There is a good usecase for asking whether a property has been set, for > instance to verify initialization. > And, of course unset has also a useful meaning. It is about the value, and > even so there are methods around a value, properties are meant to be > values. > There are definitely use-cases where that does not hold, but that is > application specific. > > >> isset() in the way you suggest would just be confusing. It would allow >> is >> to say that a property does not exist, when in fact it does exist. This >> is not logical. > From the docu: isset Determine if a variable is set and is not NULL > There is nothing confusing about isset($this->Hours) == FALSE in your > example if isset($this->seconds) == FALSE. Right, I understand how it would work, and the reasons why it would "make sense", but it just feels wrong to me. When you unset() a variable in a class, that whole variable is gone. Its not just hiding somewhere, its completely gone. If a property were to "pretend" it is not set, with an isset method, it would still be there - just hiding. That is why it does not make sense to me. - Dennis -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
