Re: [webkit-dev] Type checking / casting helpers
This all looks wonderful! One question though, why downcast(…)? Will we be adding an upcast() function? Since the answer is probably no, could we just call this cast(…)? - Sam On Sep 25, 2014, at 11:11 AM, Chris Dumez cdu...@apple.com wrote: Hi all, I started working on automatically generating the type casting helpers for HTML/SVG/MathML Elements (e.g. toHTMLDivElement()). Until now, we were generating only the type checking helpers using make_names.pl (e.g. isHTMLDivElement()). The type casting helpers had to be manually defined using NODE_TYPE_CASTS() macro. The type casting helpers are now automatically generated for most types. Part of the solution involved using a templated function for type casting because the types are forward-declared and we needed to do a static_cast() (a reinterpret_cast() could be used with forward declarations but wouldn’t be safe due to multiple inheritance). I initially had macros in place so that toHTMLDivElement() would still work and would be equivalent to downcastHTMLDivElement(). The feedback I received is that we should get rid of these macros and just use isHTMLDivElement() / downcastHTMLDivElement() everywhere. The new style is very close to C++’s is_classT() and Boost’s polymorphic_downcastT(). I actually started updating the code to do this but I should have emailed webkit-dev about this beforehand. I apologize for sending this message a bit late. Please let me know if you have feedback / concerns / questions about this change. I hope that this email gives you a better understanding of why I am making this change. As I said before, the code base is not fully ported yet so the current situation is not necessarily pretty. I will try and go through the transition as fast as I can, provided that people don’t raise any concerns about this. Please also note that these new helpers still catch unnecessary type checks / casts. As a matter of fact, those are now caught at build time instead of linking time and should give you a nice “Unnecessary type check” / “Unnecessary type cast” static assertion. Also note that the plan is to get rid of TYPE_CAST_BASE() macro entirely and extend is() / downcast() to all types, not just Nodes. Kr, -- Chris Dumez - Apple Inc. Cupertino, CA ___ webkit-dev mailing list webkit-dev@lists.webkit.org https://lists.webkit.org/mailman/listinfo/webkit-dev ___ webkit-dev mailing list webkit-dev@lists.webkit.org https://lists.webkit.org/mailman/listinfo/webkit-dev
Re: [webkit-dev] Type checking / casting helpers
That also sounds like reasonable behavior for something called cast() to me. Sent from my iPhone On Oct 2, 2014, at 5:01 PM, Benjamin Poulain benja...@webkit.org wrote: downcast fails if you do a useless cast/upcast. Benjamin On 10/2/14, 4:47 PM, Sam Weinig wrote: This all looks wonderful! One question though, why downcast(…)? Will we be adding an upcast() function? Since the answer is probably no, could we just call this cast(…)? - Sam On Sep 25, 2014, at 11:11 AM, Chris Dumez cdu...@apple.com mailto:cdu...@apple.com wrote: Hi all, I started working on automatically generating the type *casting* helpers for HTML/SVG/MathML Elements (e.g. toHTMLDivElement()). Until now, we were generating only the type *checking* helpers using make_names.pl (e.g. isHTMLDivElement()). The type *casting* helpers had to be manually defined using NODE_TYPE_CASTS() macro. The type casting helpers are now automatically generated for most types. Part of the solution involved using a templated function for type casting because the types are forward-declared and we needed to do a static_cast() (a reinterpret_cast() could be used with forward declarations but wouldn’t be safe due to multiple inheritance). I initially had macros in place so that toHTMLDivElement() would still work and would be equivalent to downcastHTMLDivElement(). The feedback I received is that we should get rid of these macros and just use isHTMLDivElement() / downcastHTMLDivElement() everywhere. The new style is very close to C++’s is_classT() and Boost’s polymorphic_downcastT(). I actually started updating the code to do this but I should have emailed webkit-dev about this beforehand. I apologize for sending this message a bit late. Please let me know if you have feedback / concerns / questions about this change. I hope that this email gives you a better understanding of why I am making this change. As I said before, the code base is not fully ported yet so the current situation is not necessarily pretty. I will try and go through the transition as fast as I can, provided that people don’t raise any concerns about this. Please also note that these new helpers still catch unnecessary type checks / casts. As a matter of fact, those are now caught at build time instead of linking time and should give you a nice “Unnecessary type check” / “Unnecessary type cast” static assertion. Also note that the plan is to get rid of TYPE_CAST_BASE() macro entirely and extend is() / downcast() to all types, not just Nodes. Kr, -- Chris Dumez - Apple Inc. Cupertino, CA ___ webkit-dev mailing list webkit-dev@lists.webkit.org mailto:webkit-dev@lists.webkit.org https://lists.webkit.org/mailman/listinfo/webkit-dev ___ webkit-dev mailing list webkit-dev@lists.webkit.org https://lists.webkit.org/mailman/listinfo/webkit-dev
Re: [webkit-dev] Type checking / casting helpers
I suggested the name; my inspiration was the boost::polymorphic_downcast function template. I also like the way a name ending with the word cast fits in with the family of static_cast, dynamic_cast, and reinterpret_cast. — Darin ___ webkit-dev mailing list webkit-dev@lists.webkit.org https://lists.webkit.org/mailman/listinfo/webkit-dev
Re: [webkit-dev] Type checking / casting helpers
Downcast is the old good name.
cast is so vague. I would assume castA(B) means: { return (A)B; }
Yong Li
From: Darin Adlermailto:da...@apple.com
Sent: 10/3/2014 3:16 AM
To: WebKit Developmentmailto:webkit-dev@lists.webkit.org
Subject: Re: [webkit-dev] Type checking / casting helpers
I suggested the name; my inspiration was the boost::polymorphic_downcast
function template. I also like the way a name ending with the word cast fits in
with the family of static_cast, dynamic_cast, and reinterpret_cast.
— Darin
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[webkit-dev] Type checking / casting helpers
Hi all, I started working on automatically generating the type casting helpers for HTML/SVG/MathML Elements (e.g. toHTMLDivElement()). Until now, we were generating only the type checking helpers using make_names.pl (e.g. isHTMLDivElement()). The type casting helpers had to be manually defined using NODE_TYPE_CASTS() macro. The type casting helpers are now automatically generated for most types. Part of the solution involved using a templated function for type casting because the types are forward-declared and we needed to do a static_cast() (a reinterpret_cast() could be used with forward declarations but wouldn’t be safe due to multiple inheritance). I initially had macros in place so that toHTMLDivElement() would still work and would be equivalent to downcastHTMLDivElement(). The feedback I received is that we should get rid of these macros and just use isHTMLDivElement() / downcastHTMLDivElement() everywhere. The new style is very close to C++’s is_classT() and Boost’s polymorphic_downcastT(). I actually started updating the code to do this but I should have emailed webkit-dev about this beforehand. I apologize for sending this message a bit late. Please let me know if you have feedback / concerns / questions about this change. I hope that this email gives you a better understanding of why I am making this change. As I said before, the code base is not fully ported yet so the current situation is not necessarily pretty. I will try and go through the transition as fast as I can, provided that people don’t raise any concerns about this. Please also note that these new helpers still catch unnecessary type checks / casts. As a matter of fact, those are now caught at build time instead of linking time and should give you a nice “Unnecessary type check” / “Unnecessary type cast” static assertion. Also note that the plan is to get rid of TYPE_CAST_BASE() macro entirely and extend is() / downcast() to all types, not just Nodes. Kr, -- Chris Dumez - Apple Inc. Cupertino, CA ___ webkit-dev mailing list webkit-dev@lists.webkit.org https://lists.webkit.org/mailman/listinfo/webkit-dev
