On Mon, Jan 30, 2017 at 12:51 PM, Nathan Bubna <nbu...@gmail.com> wrote:
> On Sat, Jan 28, 2017 at 11:23 AM, Alex Fedotov <a...@kayak.com> wrote: > >> You guys should definitely leave a way of disabling the toString() >> conversion in boolean expressions. >> > > Seems reasonable, and also familiar; this may have been discussed before. > Oh, yes, and built. I knew this was familiar. :) See http://velocity.apache.org/engine/2.0/configuration.html : directive.if.tostring.nullcheck = true > >> There are many places where people do null checks if #if($obj)...#end. >> >> Classes almost never return an empty string or null string from the >> toString call. Even worse some classes may use toString for debugging >> purposes and produce very long strings (including nested objects, etc.). >> In the code above that would be a huge inefficiency. >> > > Yes, that's part of the motive to have this lookup chain. If there's a > match higher up, toString() is avoided. Big deal for maps and arrays. > > >> >> Alex >> >> On Sat, Jan 28, 2017 at 2:06 PM, Nathan Bubna <nbu...@gmail.com> wrote: >> >> > Shame that i can't remember anymore all my reasons for wanting those >> > "getAs<Type>" lookups. Wondering why getAsNumber and getAsBoolean are >> here >> > too. Anyone else recall the use case? And assuming that i had good >> reason >> > (that did happen sometimes <grin>), i wonder why i pushed for bucking >> the >> > "to<Type>()" convention. >> > >> > As for the literals, the thought of them being used in #if statements >> in a >> > template language is cringe-inducing. What's the use-case? Temporary >> > debugging hacks? If so, part of me thinks maybe only 'true' should even >> be >> > allowed. >> > >> > On Sat, Jan 28, 2017 at 7:15 AM, Claude Brisson <cla...@renegat.net> >> > wrote: >> > >> > > >> > > >> > >>>> What is the problem? >> > >>>> >> > >>>> Velocity "truthiness": >> > >>> https://issues.apache.org/jira/browse/VELOCITY-692 >> > >>> >> > >>> It should definitely be part of 2.0. I missed it because the issue >> was >> > >>> closed, we should have opened a 2.0 one to remember it. >> > >>> >> > >> >> > >> Thats's the problem if a closed/resolved issue does not have an >> > >> assignee. You never know who handled it without reading the entire >> > >> thread. A ticket should always have an assignee if code has been >> > changed. >> > >> >> > >> >> > > Here's what had been specified by Nathan at the time (order is >> > meaningful, >> > > and falseness seems easier to specify than truth): >> > > >> > > $obj is null >> > > $obj is boolean false >> > > $obj returns false from getAsBoolean() (provided there is such a >> method) >> > > $obj is empty string (CharSequence w/length 0) >> > > $obj returns true from isEmpty() (provided there is such a method) >> > > $obj is array of length 0 >> > > $obj returns null from getAsString() (provided there is such a method) >> > > $obj returns empty string from getAsString() (provided there is such a >> > > method) >> > > $obj returns null from getAsNumber() (provided there is such a method) >> > > $obj returns 0 from length() or size() (provided there is such a >> method) >> > > $obj returns empty string from toString() (provided there is such a >> > method) >> > > >> > > Regarding this spec: >> > > - I'm not sure about getAsString() ; toString() is usually the >> standard >> > > way of getting the String representation and should be enough. >> > > - I'm not convinced by the fact that zero should be true. I hear >> > Nathan's >> > > point that for a display language, zero is as legitimate as any other >> > > number to be displayed. But it breaks the principle of least surprise, >> > > since each and every other language around, when not forbidding number >> > > towards boolean implicit conversion, consider zero as false. >> > > >> > > So I'd rather go with: >> > > >> > > $obj is null >> > > $obj is Boolean false >> > > $obj is Number zero (whatever Number variant) >> > > $obj returns false from getAsBoolean() (provided there is such a >> method) >> > > $obj is empty string (CharSequence w/length 0) >> > > $obj returns true from isEmpty() (provided there is such a method) >> > > $obj is array of length 0 >> > > $obj returns null from getAsNumber() (provided there is such a method) >> > > $obj returns 0 from length() or size() (provided there is such a >> method) >> > > $obj returns empty string from toString() (provided there is such a >> > method) >> > > >> > > Also, I noticed that Velocity weren't very consistent with literals. >> The >> > > only literal returning true is the 'true' literal. "foo" is false, >> > whereas >> > > it should be consistent with $foo containing "foo". >> > > >> > > Claude >> > > >> > > >> > > --------------------------------------------------------------------- >> > > To unsubscribe, e-mail: dev-unsubscr...@velocity.apache.org >> > > For additional commands, e-mail: dev-h...@velocity.apache.org >> > > >> > > >> > >> > >
