On 30/01/2017 22:08, Nathan Bubna wrote:
On Sat, Jan 28, 2017 at 4:38 PM, Claude Brisson <cla...@renegat.net> wrote:
On 28/01/2017 20:23, Alex Fedotov wrote:
You guys should definitely leave a way of disabling the toString()
conversion in boolean expressions.
There are many places where people do null checks if #if($obj)...#end.
Classes almost never return an empty string or null string from the
toString call. Even worse some classes may use toString for debugging
purposes and produce very long strings (including nested objects, etc.).
In the code above that would be a huge inefficiency.
I totally agree that a great percentage of #if($foo) statements are just
here to check for nulls. And the current behavior of returning false for
empty strings, empty arrays and empty maps could already be problematic in
this regard
And I think I have a good proposal about that.
Since
$foo differenciate null and "" (by displaying the first and not the second)
$!foo assimilates null and "" (by hiding both)
why not consider that:
#if($foo) returns false for null and true for everything else, and
#if($!foo) returns false for null, "", zero, empty arrays, etc...
Yikes. That looks like a scary combo of significant and subtle. It would
need to be well-highlighted in the release notes, change logs, docs, etc.
I might like it. Maybe. I dunno. The syntax is giving my tired brain
spasms, given that it's close to the very different #if( !$foo ). I can't
"read" it, if that make sense. It's like a complex regexp, where i have to
think my way through it, instead of just reading it.
Is there a use-case for having both supported in the same template?
Otherwise, it might be better to avoid the subtlety and just support a
configuration property for how clever templates can be with evaluating #if(
$foo ).
Maybe we do the full lookup chain by default, but let people set a
directive.if.emptycheck = false
That would limit it to just checking for false or null values (presumably
still including getAsBoolean, getAsString, and toString), but skipping the
"empty" checks.
Then the high performance move is:
directive.if.emptycheck = false
directive.if.tostring.nullcheck = false
But the default is for both to be true.
That should be enough, yes.
I like this syntax trick, but it remains a trick, so I won't stand for
it. Let's forget it.
However, I wonder if we should rework the lookup chain so that it never
reaches bottom methods for standard types, collections and arrays. The
lookup chain may pretty well mix false and true checks. Like: if it's an
array, return whether or not it's empty and don't go further.
Claude
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