[erlyweb-list] Re: s and other non-component data</span></a></span> </h1> <p class="darkgray font13"> <span class="sender pipe"><a href="/search?l=erlyweb@googlegroups.com&q=from:%22David+King%22" rel="nofollow"><span itemprop="author" itemscope itemtype="http://schema.org/Person"><span itemprop="name">David King</span></span></a></span> <span class="date"><a href="/search?l=erlyweb@googlegroups.com&q=date:20071116" rel="nofollow">Fri, 16 Nov 2007 17:55:17 -0800</a></span> </p> </div> <div itemprop="articleBody" class="msgBody"> <!--X-Body-of-Message--> <pre> >> Would it make sense to hack in a return value from the controller >> function? Something like: >> {return_with_meta,[{title,"Foo"},{link_rel,"next",link_to_page_2()}], >> [{data,"foo"}, >> {ewc,...}]} >> (with a better name, since "return_with_meta" doesn't sound all that >> great to me). But then I'm not sure how one could extract that from >> the rendered view. Maybe pass only the second tuple-item to the view, >> and pass both the first item and the second to the controller. Many >> many questions. I'll have to think about it some more. > I think that's a very good idea. There may be issues if multiple > subcomponents return the same metadata (or at least the same keys), > but then I guess ErlyWeb will just pick the first one. There are also > questions regarding how the metadata will be passed around (should it > be passed to a components siblings and or only its parents?) -- I'll > have to think about it and make sure all the bases are covered.</pre><pre> I really like the component system, so I'd definitely like to get your feedback on my ideas since it's already going in a good direction. I wouldn't expect the siblings to be guaranteed to receive it (since clearly you can't guarantee that they all do, since some may have already been evaluated, or may be being evaluated at the same time), but I wouldn't expect them to be guaranteed to *not* receive it. Since the yaws_arg is being re-vamped anyway, maybe this should be carried around on the yaws_arg. A simple plist is probably fine for it. Then as the yaws_arg is returned changed it can be passed through changed. Then make all subcomponents pass the yaws_arg implicitly: so instead of {ewc,controller,func,[A,Foo]} calling func(A,Foo), make {ewc,controller,func,[Foo]]} call fun(A,Foo). That way you're not passing a stale yaws_arg accidentally. This is of course a backwards- breaking change, but not a difficult one to fix, since all of the erlyweb code that I've seen and written passes it to the sub- components anyway (even if it's not necessarily used). Otherwise, you end up all of the components doing something like this: show(A,Foo) NewA=yaws_arg:add_meta(A,[{title,get_the_title()}]), {return_with_meta,[{ewc,func,[NewA,Foo]}], NewA}. (once again, with better names than return_with_meta and add_meta) The worry here is that the subcomponents have to be called with NewA instead of A, which seems ripe for forgetting to me (especially if the yaws_arg some some validation before it passes it on; you could pass invalid data to sub-components this way). I haven't looked at the contents of the yaws_arg, but if it's tagged with a type, then you could just do this: show(A,Foo) [_New_yaws_arg=yaws_arg:add_property(A,[{title,get_the_title()}]), {ewc,func,[Foo]}]. Since erlyweb already knows to check the returned list for {ewc} and whatnot, it could just check for a new yaws_arg and start using that one. The problem there is that it forces {ewc}s to be processed serially (since what do you do when you get two conflicting yaws_args?), which my erlyweb does not (and given your blog post on a potential {concurrent,[{ewc,...}]}, I suspect this won't be a guarantee forever). Another idea is to just add another return value from controller functions: show(A,Foo) [{add_property,{title,get_the_title()}}, {add_property,{time_to_live,two_weeks()}} {ewc,controller,func,[Foo]}, {ewc,controller,fun2,[yaws_arg:get_property(cookies)]]. (this was has my implicit-passing of yaws_args, but it's not necessary; not doing so does preclude children retrieving properties from parents, but if they need that they should pass it as an argument anyway). That doesn't carry the assumption that they are processed serially. It prevents parents from getting to children's properties without using {phased,Ewcs,...}, but that's probably not a problem, and isn't very avoidable. (I think all of these options do, if they want to do post-processing of any kind). Personally, I like the last option, but it looks like it would require quite a few changes to the way that the erlyweb:ewc/N functions work Any other ideas? How does that last one look? >>> Btw, just curious, what parts of ErlyWeb are you rewriting? >> [...] >> Mostly large swaths of erlydb and erlydb_mnesia (in ways that make it >> work better with mnesia, but that make it incompatible with other >> DBMSs, which of course the current incarnation avoids). I may end up >> having to revert this if mnesia can't handle millions of objects, >> with which it seems to be having trouble once they start to become >> larger objects than simple tuples. I've hacked in a few return and >> 'EXIT' handlers from controller functions for special circumstances, >> like when I want to return a 400- or 500-level HTTP response along >> with other information. I might try to hack in some WebDAV handling >> stuff, as I'm considering writing a desktop client for my app in the >> future and that seems the easiest way to get the data to and from the >> desktop client. I haven't decided what that's going to look like yet. >> It looks like I may be hacking in a return value to return extended >> information to parent controller functions, like <title> tags. but I >> want to decide how it should work, first. It sounds like it's just >> not a concern to the two biggest users of erlyweb > > If you want to contribute this feature (or any other feature that you > think will be useful to other ErlyWeb users) I'll be happy to accept > your code. > > Yariv > >> >> >>> >>> Yariv >>> >>> On Nov 16, 2007 10:19 AM, David King <[EMAIL PROTECTED]> wrote: >>>> >>>> erlyweb uses a component system for rendering pages. It makes >>>> most of >>>> my controller functions return lists like this: >>>> >>>> [{data,post:title(Post)}, >>>> {ewc,post,contents,[A,Post]}, >>>> {ewc,comment,comments,[A,post:comments(Post)]}] >>>> >>>> The view function then looks like: >>>> >>>> <%@ show([Title,Contents,Comments]) %> >>>> <h1><% Title %></h1> >>>> <div class="post_contents"><% Contents %></div> >>>> <ul class="comments><% Comments %></ul> >>>> >>>> I really like this, because it allows me to separate the view-logic >>>> for things like contents and comments out from each other, which >>>> makes changing the behaviour of these quite simple, localised, and >>>> re- >>>> useable. (In fact, as I re-write portions of erlyweb for my >>>> purposes, >>>> the component system is something that I haven't touched at all >>>> because it works quite well.) However, it has an inherent >>>> limitation: >>>> none of those functions can return data to be rendered outside of >>>> their components. In my case, I'd like to be able to set <title> >>>> tags, which means that the top-level controller function (by top- >>>> level, I mean the one referenced in the URL; like in /post/show/12, >>>> the top-level controller function would be show/2) needs to somehow >>>> return information to be rendered outside its little sandbox. >>>> >>>> I see that Vimagi doesn't set <title> tags (neither <http:// >>>> vimagi.com/p/0PXmMRe6hGV> nor <<a rel="nofollow" href="http://vimagi.com/users/feeling3_4">http://vimagi.com/users/feeling3_4</a>> >>>> set one, at least, and those are where I'd expect to see them), but >>>> BeerRiot does (<<a rel="nofollow" href="http://beerriot.com/beer/view/1751">http://beerriot.com/beer/view/1751</a>>; BTW I do love >>>> the idea of having a controller called "beer_controller"). >>>> >>>> It isn't limited to <title>s (for instance, I may want to alert the >>>> browser that an RSS equivalent of this page exists, or what the >>>> caching TTL is for this page in the HTTP headers). Conceptually, >>>> how >>>> would one go about returning this extra information, while still >>>> using the component system (I now have a lot of code that uses it >>>> that I'd like to not re-write :) )? >>>> >>>> >>>> >>>>> >>>> >>> >>> >> >>> >> > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "erlyweb" group. To post to this group, send email to erlyweb@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at <a rel="nofollow" href="http://groups.google.com/group/erlyweb?hl=en">http://groups.google.com/group/erlyweb?hl=en</a> -~----------~----~----~----~------~----~------~--~--- </pre> </div> <div class="msgButtons margintopdouble"> <ul class="overflow"> <li class="msgButtonItems"><a class="button buttonleft " accesskey="p" href="msg00106.html">Previous message</a></li> <li class="msgButtonItems textaligncenter"><a class="button" accesskey="c" href="index.html#00107">View by thread</a></li> <li class="msgButtonItems textaligncenter"><a class="button" accesskey="i" href="maillist.html#00107">View by date</a></li> <li class="msgButtonItems textalignright"><a class="button buttonright " accesskey="n" href="msg00110.html">Next message</a></li> </ul> </div> <a name="tslice"></a> <div class="tSliceList margintopdouble"> <ul class="icons monospace"> <li class="icons-email"><span class="subject"><a href="msg00102.html">[erlyweb-list] <title>s and other non-component data</a></span> <span class="sender italic">David King</span></li> <li><ul> <li class="icons-email"><span class="subject"><a href="msg00104.html">[erlyweb-list] Re: <title>s and other non-component...</a></span> <span class="sender italic">Yariv Sadan</span></li> <li><ul> <li class="icons-email"><span class="subject"><a href="msg00105.html">[erlyweb-list] Re: <title>s and other non-compo...</a></span> <span class="sender italic">David King</span></li> <li><ul> <li class="icons-email"><span class="subject"><a href="msg00106.html">[erlyweb-list] Re: <title>s and other non-c...</a></span> <span class="sender italic">Yariv Sadan</span></li> <li><ul> <li class="icons-email tSliceCur"><span class="subject">[erlyweb-list] Re: <title>s and other n...</span> <span class="sender italic">David King</span></li> <li><ul> <li class="icons-email"><span class="subject"><a href="msg00110.html">[erlyweb-list] Re: <title>s and ot...</a></span> <span class="sender italic">Yariv Sadan</span></li> <li><ul> <li class="icons-email"><span class="subject"><a href="msg00113.html">[erlyweb-list] Re: <title>s an...</a></span> <span class="sender italic">David King</span></li> <li><ul> <li class="icons-email"><span class="subject"><a href="msg00116.html">[erlyweb-list] Re: <title>...</a></span> <span class="sender italic">Yariv Sadan</span></li> <li class="icons-email"><span class="subject"><a href="msg00118.html">[erlyweb-list] Re: <title>...</a></span> <span class="sender italic">David King</span></li> <li class="icons-email"><span class="subject"><a href="msg00119.html">[erlyweb-list] Re: <title>...</a></span> <span class="sender italic">Yariv Sadan</span></li> <li class="icons-email"><span class="subject"><a href="msg00120.html">[erlyweb-list] Re: <title>...</a></span> <span class="sender italic">David King</span></li> <li class="icons-email"><span class="subject"><a href="msg00131.html">[erlyweb-list] Re: <title>...</a></span> <span class="sender italic">Yariv Sadan</span></li> <li class="icons-email"><span class="subject"><a href="msg00132.html">[erlyweb-list] Re: <title>...</a></span> <span class="sender italic">David King</span></li> <li class="icons-email"><span class="subject"><a href="msg00134.html">[erlyweb-list] Re: <title>...</a></span> <span class="sender italic">Yariv Sadan</span></li> <li class="icons-email"><span class="subject"><a href="msg00121.html">[erlyweb-list] Re: <title>...</a></span> <span class="sender italic">David King</span></li> </ul> </ul> </ul> </ul> </ul> </ul> </ul> </ul> </div> <div class="overflow msgActions margintopdouble"> <div class="msgReply" > <h2> Reply via email to </h2> <form method="POST" action="/mailto.php"> <input type="hidden" name="subject" value="[erlyweb-list] Re: <title>s and other non-component data"> <input type="hidden" name="msgid" value="7DA68D87-4DC4-4FBF-B86B-05939E34470C@ketralnis.com"> <input type="hidden" name="relpath" value="erlyweb@googlegroups.com/msg00107.html"> <input type="submit" value=" David King "> </form> </div> </div> </div> <div class="aside" role="complementary"> <div class="logo"> <a href="/"><img src="/logo.png" width=247 height=88 alt="The Mail Archive"></a> </div> <form class="overflow" action="/search" method="get"> <input type="hidden" name="l" value="erlyweb@googlegroups.com"> <label class="hidden" for="q">Search the site</label> <input class="submittext" type="text" id="q" name="q" placeholder="Search erlyweb"> <input class="submitbutton" name="submit" type="image" src="/submit.png" alt="Submit"> </form> <div class="nav margintop" id="nav" role="navigation"> <ul class="icons font16"> <li class="icons-home"><a href="/">The Mail Archive home</a></li> <li class="icons-list"><a href="/erlyweb@googlegroups.com/">erlyweb - 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