RE: [PHP-DEV] Scalar type hinting

From: Adam Richardson [mailto:simpleshot@gmail.com] On Tue, Feb 28, 2012 at 2:53 PM, John Crenshaw <johncrenshaw@priacta.com<mailto:johncrenshaw@priacta.com>> wrote: OK everyone, it seems that some people have forgotten or missed the original agreement that this thread started with. There is a communication disconnect ("strict typing" means horribly different things to different people right now). Please read through and understand the following terminology before continuing to post on this thread. We've agreed to the following terms: - "Strict Typing" means the super strict old C style typing *with no implicit conversions*. (If you really think this is what you want, you are probably mistaken. Look through prior discussions on this topic. This fails for numerous reasons, including the fact that almost every input to PHP is a string.) Where is the term "strict typing" coming from? I've not seen this used to describe any type system (doesn't mean it's not been used, but I'd really like to see the usage so I can understand the label.) Adam, When you say you want "Strict" or "Strong" typing, this (case 1) is what the opponents of stronger typing think you are asking for, which is why I've defined it this way. There have been a tiny handful of individuals that really are asking for this, but most people don't really want this level of strictness. Also, this level of strictness is fundamentally at odds with the nature of PHP, and it's just never going to happen. The level of typing in this first case is littered with problems. I won't get into it all, but you can read prior discussions in the archives to see it. Look for the passionate arguments made by typing opponents that talk about "massive changes", "destroying the language", and "Go use JSP". Scattered in there are some occasional explanations of the actual core issues, all of which refer to this level of typing. (Incidentally, even C++ is not this strict, so this really isn't what you want, I'm sure of it. If this is what you want, then this isn't the thread for you, because this is *not* what will be advocated or discussed here.) - "Weak Typing" means types in the same sense that the PHP documentation uses types (for example, the docs indicate substr(string, integer), and substr(12345, "2") == "345".) (If you think you want "strict typing", this is probably what you mean.) Doesn't weak typing mean that the language implicitly converts types for use according to a set of rules? The opposite of this being strong typing, which means the language does not perform implicit conversions. "Weak" here really means weaker than the "Strong" above, but stronger than "none". Right now PHP has no typing whatsoever. "weak typing" WOULD be typing, but it is flexible, optional, and aggressively uses implicit conversions. For comparison, by these definitions C++ is halfway between "weak typing" and "strong typing" (by virtue of operator overloads, overloaded functions, and cast operators.) This "Weak typing" will give you what you want, and it can work. Most importantly, it is *not* the thing that goes bump in the night for most strong typing opponents, which means it is probably possible to gather sufficient support for this. This discussion is focused on developing a rock solid proposal for "weak typing". - "No Scalar Typing" should be used to indicate the current system (where there is no provision for hinting at scalar types.) And, curious about the "No Scalar Typing"? This is PHP right now. The language has no provision whatsoever for scalar types. Function parameters can be hinted as an array or as a specific class/interface, but otherwise they are assumed to be absolutely anything. I know that for people with a lot of experience in a strongly typed language this sounds like what they would normally call "Weak Typing", but it's a 3rd level. "Weak Typing" under these definitions is a lot stronger than what you would call "weak", but it's much weaker than what strong typing opponents would call "strong". It's going to take some time to get used to the semantics, but if you want any typing enhancements you're going to have to speak the language of the people you want to convince. The communication disconnect here has been sinking this proposal for a decade. John Crenshaw Priacta, Inc.