[stringtemplate-interest] separator: a fix or breaking backward compatibility?

[Terence Parr]

Hi,

I've built an awesome example using ST for the book. Given a single  
Class object, ST will generate all of the SQL and Java code necessary  
to serialize and deserialize objects of that type. no Java code used  
at all to generate the output :)

HOWEVER, it exposed a serious problem in ST behavior.  Unless I can  
fix this, I will have to add some Java code to do processing to  
generate the SQL, which I don't want to do.

Consider the following generation of a comma separated list of names:

<names; separator=",">

There is a separator generated in between every name in the list. If  
names is null, nothing is generated. If names has length one, there is  
no separator generated.

Now, consider the following anonymous template application to a list  
of names:

<names:{n | <if(n.cool)><n><endif>}; separator=",">

It will only a name if that name is "cool" (has field cool true or  
method isCool() true). The problem is that when n.cool is false, you  
still get an operator.

This is a serious problem in terms of generating output because there  
is no way to get around this bug or feature! The answer must lie in  
what the result of a false IF is exactly. Is it missing (null) or  
empty ("")???

If the result is missing, then no separator should be generated.  
However, if it's empty, we should get a separator.

I'm proposing that the result is missing not empty. If we truly want  
empty, we can do this

<names:{n | <if(n.cool)><n><else><endif>}; separator=",">

The else clause is present but empty, right?

I'm not sure how hard it is to fix this IF problem. But, I need a vote  
from people to tell me if it will break something they rely on.

This would be a bug fix release like 3.2.1 or perhaps 3.3 if I add any  
small features. This will not be the overall rewrite, which I will  
begin after the book.

Amazing how writing a book exposes all of the weird nooks and crannies  
in a tool. Ha! Book-driven functionality testing :)

So, should I "fix" it?

Ter