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. > 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 > > > > > > > > >
