Re: [Lift] Snippet lifetime
Hello, Yes, the article is out of date now... Lift now makes sure that multiple references to a single snippet in the same request context use the same instance of that snippet. I've updated the wiki page a bit: http://wiki.github.com/dpp/liftweb/about-snippets, if some lift gurus would want to review. So far it lists the following snippet kinds: * reflection * dispatch * singleton dispatch * stateful I'm not sure if there are any other, but if there are, maybe somebody could mention them there, so that people would be at least aware of their existence and look up in the source code later. -- Adam -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en.
Re: [Lift] Snippet lifetime
Nope, that looks cool - thanks for updating that. Cheers, Tim On 29 Dec 2009, at 10:26, Adam Warski wrote: Hello, Yes, the article is out of date now... Lift now makes sure that multiple references to a single snippet in the same request context use the same instance of that snippet. I've updated the wiki page a bit: http://wiki.github.com/dpp/liftweb/about-snippets, if some lift gurus would want to review. So far it lists the following snippet kinds: * reflection * dispatch * singleton dispatch * stateful I'm not sure if there are any other, but if there are, maybe somebody could mention them there, so that people would be at least aware of their existence and look up in the source code later. -- Adam -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en. -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en.
Re: [Lift] Snippet lifetime
On Mon, Dec 28, 2009 at 8:04 AM, Adam Warski a...@warski.org wrote: Hello, Yes, the article is out of date now... Lift now makes sure that multiple references to a single snippet in the same request context use the same instance of that snippet. I see, so the rationale behind using dispatch snippets is out of date also. Except that you save one reflection call per page/request. So are there any reasons to use DispatchSnippets now? Yes. While they require a tad more code, they are type safe. My take on by convention is it's great when you and one or two other people are whipping stuff together in a hurry. As the project moves from rapid prototyping to sustainable coding, being explicit with the dispatch makes it easier for others to follow the code flow. Reflection snippets do not have the same scope as request vars... rather, the snippet is held in a request var. Which essentialy makes them have the same scope as request vars :) By the way, is there a true request-scope variable? I saw that there's TransientRequestVar, but it's private in the liftweb package. There was a particular use case for the TransientRequestVar, so I added it and made it available only to the http package. If you can describe a place where the current RequestVars do not work for you, we can talk some more. Adam Cheers, Tim On 28 Dec 2009, at 14:33, Adam Warski wrote: Hello, on the wiki page about reflection snippets ( http://wiki.github.com/dpp/liftweb/about-snippets), it is written: Every time you call the reflection snippet in your markup code, a new instance is instantiated and the appropriate method invoked However this doesn't seem to be true (I'm using 1.1-M8). I have modified the example in the tutorial to use ajax to submit the form (as Marius and others advised me in another thread), and I discovered that after I add an item, then try to add another one, the first one is modified, which would mean that the same snippet instance is used (the snippet - TD - is a reflection snippet, as far as I understand the terminology). That would mean that reflection snippets have the same scope as RequestVars, that is that there's at most one instance per rendered page. Marius wrote that this changes recently, so maybe it's a side-effect? Also, do you think that RequestVar is a good name? For me it suggests a variable which has a lifecycle only for one http request. In the Seam framework, for example, there are two scopes: request and page (and many others), the first one being a true request scope, the second having essentially the same scope as RequestVar. So maybe it should be called PageVar? -- Adam -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.comliftweb%2bunsubscr...@googlegroups.com . For more options, visit this group at http://groups.google.com/group/liftweb?hl=en. -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.comliftweb%2bunsubscr...@googlegroups.com . For more options, visit this group at http://groups.google.com/group/liftweb?hl=en. -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.comliftweb%2bunsubscr...@googlegroups.com . For more options, visit this group at http://groups.google.com/group/liftweb?hl=en. -- Lift, the simply functional web framework http://liftweb.net Beginning Scala http://www.apress.com/book/view/1430219890 Follow me: http://twitter.com/dpp Surf the harmonics -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en.
Re: [Lift] Snippet lifetime
On Tue, Dec 29, 2009 at 3:36 PM, Ross Mellgren dri...@gmail.com wrote:
On Dec 29, 2009, at 6:28 PM, David Pollak wrote:
On Mon, Dec 28, 2009 at 8:04 AM, Adam Warski a...@warski.org wrote:
Hello,
Yes, the article is out of date now... Lift now makes sure that multiple
references to a single snippet in the same request context use the same
instance of that snippet.
I see, so the rationale behind using dispatch snippets is out of date
also. Except that you save one reflection call per page/request. So are
there any reasons to use DispatchSnippets now?
Yes. While they require a tad more code, they are type safe. My take on
by convention is it's great when you and one or two other people are
whipping stuff together in a hurry. As the project moves from rapid
prototyping to sustainable coding, being explicit with the dispatch makes it
easier for others to follow the code flow.
Reflection snippets do not have the same scope as request vars...
rather, the snippet is held in a request var.
Which essentialy makes them have the same scope as request vars :)
By the way, is there a true request-scope variable? I saw that there's
TransientRequestVar, but it's private in the liftweb package.
There was a particular use case for the TransientRequestVar, so I added it
and made it available only to the http package.
If you can describe a place where the current RequestVars do not work for
you, we can talk some more.
I've wanted them to cache information that isn't trivial to compute, but
that I wanted to be regenerated on each AJAX call, for an app with a page
that could be on-screen and doing AJAX calls for perhaps half an hour or
more.
object Foo extends RequestVar[Box[BigHairyComputation]](Empty)
def myAjaxCallback(): JsCmd = Foo.doWith(computeValueForThisRequest) {
// do stuff related to doing the Ajax call
}
In the above code, the lifetime of the value calculated by
computeValueForThisRequest is the call to doWith.
In the end I whipped up controlled cache invalidation and stashed the
cached information on a StatefulSnippet.
I think they would be a good generally useful thing to have, personally.
-Ross
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Re: [Lift] Snippet lifetime
Yes, the article is out of date now... Lift now makes sure that multiple references to a single snippet in the same request context use the same instance of that snippet. Reflection snippets do not have the same scope as request vars... rather, the snippet is held in a request var. Cheers, Tim On 28 Dec 2009, at 14:33, Adam Warski wrote: Hello, on the wiki page about reflection snippets (http://wiki.github.com/dpp/liftweb/about-snippets), it is written: Every time you call the reflection snippet in your markup code, a new instance is instantiated and the appropriate method invoked However this doesn't seem to be true (I'm using 1.1-M8). I have modified the example in the tutorial to use ajax to submit the form (as Marius and others advised me in another thread), and I discovered that after I add an item, then try to add another one, the first one is modified, which would mean that the same snippet instance is used (the snippet - TD - is a reflection snippet, as far as I understand the terminology). That would mean that reflection snippets have the same scope as RequestVars, that is that there's at most one instance per rendered page. Marius wrote that this changes recently, so maybe it's a side-effect? Also, do you think that RequestVar is a good name? For me it suggests a variable which has a lifecycle only for one http request. In the Seam framework, for example, there are two scopes: request and page (and many others), the first one being a true request scope, the second having essentially the same scope as RequestVar. So maybe it should be called PageVar? -- Adam -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en. -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en.
Re: [Lift] Snippet lifetime
Hello, Yes, the article is out of date now... Lift now makes sure that multiple references to a single snippet in the same request context use the same instance of that snippet. I see, so the rationale behind using dispatch snippets is out of date also. Except that you save one reflection call per page/request. So are there any reasons to use DispatchSnippets now? Reflection snippets do not have the same scope as request vars... rather, the snippet is held in a request var. Which essentialy makes them have the same scope as request vars :) By the way, is there a true request-scope variable? I saw that there's TransientRequestVar, but it's private in the liftweb package. Adam Cheers, Tim On 28 Dec 2009, at 14:33, Adam Warski wrote: Hello, on the wiki page about reflection snippets (http://wiki.github.com/dpp/liftweb/about-snippets), it is written: Every time you call the reflection snippet in your markup code, a new instance is instantiated and the appropriate method invoked However this doesn't seem to be true (I'm using 1.1-M8). I have modified the example in the tutorial to use ajax to submit the form (as Marius and others advised me in another thread), and I discovered that after I add an item, then try to add another one, the first one is modified, which would mean that the same snippet instance is used (the snippet - TD - is a reflection snippet, as far as I understand the terminology). That would mean that reflection snippets have the same scope as RequestVars, that is that there's at most one instance per rendered page. Marius wrote that this changes recently, so maybe it's a side-effect? Also, do you think that RequestVar is a good name? For me it suggests a variable which has a lifecycle only for one http request. In the Seam framework, for example, there are two scopes: request and page (and many others), the first one being a true request scope, the second having essentially the same scope as RequestVar. So maybe it should be called PageVar? -- Adam -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en. -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en. -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en.
Re: [Lift] Snippet lifetime
On Mon, Dec 28, 2009 at 8:04 AM, Adam Warski a...@warski.org wrote: Hello, Yes, the article is out of date now... Lift now makes sure that multiple references to a single snippet in the same request context use the same instance of that snippet. I see, so the rationale behind using dispatch snippets is out of date also. Except that you save one reflection call per page/request. So are there any reasons to use DispatchSnippets now? DispatchSnippets support dynamic dispatch: you can change how tags are dispatched based on some state. With (reflection-based) snippets, there's a direct binding between the tag and the class name + method. Well, unless you override LiftRules.snippetDispatch. alex -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en.
Re: [Lift] Snippet lifetime
Yes, the article is out of date now... Lift now makes sure that multiple references to a single snippet in the same request context use the same instance of that snippet. I see, so the rationale behind using dispatch snippets is out of date also. Except that you save one reflection call per page/request. So are there any reasons to use DispatchSnippets now? DispatchSnippets support dynamic dispatch: you can change how tags are dispatched based on some state. With (reflection-based) snippets, there's a direct binding between the tag and the class name + method. Well, unless you override LiftRules.snippetDispatch. Ah right. Thanks. I'll modify the wiki once I gather all the answers :) Adam -- You received this message because you are subscribed to the Google Groups Lift group. To post to this group, send email to lift...@googlegroups.com. To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/liftweb?hl=en.
