Hello, Rich. I'm afraid I'm not quite understanding your situation.
There are 3 different occasions when your SLE may come into play: 1. When the Cheetah report generator starts up. This is when your SLE gets instantiated, that is, its __init__ function, if any, gets invoked. This happens only once per report generation. 2. When a template gets generated. This is when get_extension_list() is invoked, which happens once per template. For the standard search list that comes with weeWX, this is when the top of the tag chain (class TimeBinder), described in How tags work <http://weewx.com/docs/customizing.htm#how_tags_work>, gets created, however, the chain itself does not actually get chased. 3. When looking for a tag. The Cheetah template engine will probe all the search list extensions looking for a specific tag. It does this by calling __getattr__ repeatedly with the tag name as an argument --- a cheap call. If it finds a hit, then this is typically when the expensive stuff starts happening. Note that this probing will happen *for every tag*, whether your tag or not. But, the rest of the tag chain gets invoked only if Cheetah finds a hit. For the search list that comes with weeWX nothing expensive happens until the very end of the tag chain. That's when the database lookups start happening. You say your expensive calculation is happening 14 times. If you have 14 of your tags sprinkled throughout the templates, then this is unavoidable: 14 requests for your tag, 14 calculations. However, if you expect all 14 tags to produce the same results (an example would be $station.altitude) then you should be doing your calculation farther up the stack described above. Perhaps you should be doing the calculation in get_extension_list() or even __init__. I hope this make sense. If not, give us some more specifics. Cheers, -tk On Wed, Apr 4, 2018 at 10:26 PM, gjr80 <[email protected]> wrote: > Hi Rich, > > Unfortunately the SLEs are applied to each report in a skin. Can you pull > out the template concerned into its own skin and use the SLE in that skin > only? > > Gary > > > On Thursday, 5 April 2018 14:59:13 UTC+10, Rich Altmaier wrote: >> >> I'm creating a Report extension which is fairly expensive to calculate. >> When I add my extension to skin.conf, with the usual >> search_list_extensions under CheetahGenerator, I find my extension is >> invoked about 14 times, which costs many seconds. Is it possible to make >> a Report extension apply to a selected file generation, such as in >> generating index.html only? >> Thank you! >> Rich >> >> -- > You received this message because you are subscribed to the Google Groups > "weewx-user" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
