[Templates] Keeping intended white space

[mail@seamons.com]

Wow.  That is quite some request.  It actually  seems closer to the TRIM 
directive than it does the CHOMP - but it is different from that also.  
Essentially it is a TRIM every TAG, but only the whitespace on the same line, 
and only if the TAG returned an empty string.

Looking at the internals - I don't think that this would be very feasible 
without performance hit.  It would be dynamically changing the string 
appended to $output in the executed perl depending upon the return value of 
the TAG.

The reason the pre and post chomp things work now is because they are 
independent of what is in the directive TAG and can modify the parsed and 
stored text during the compilation process.  This request is asking that to 
happen later which is why I said it is closer to the TRIM directive - which 
happens later.  Though it is theoretically possible to add this, it would 
introduce a performance hit for every directive call (I guess it would just 
be an if check - but there already would be many).

As this seems to be a fairly limited use case, I'd go with the post processing 
method you have, but you could extended it to put a "# generated" tag at the 
end of any line that may have been generated.  You could then remove lines 
that match "^\s*# generated" and you could cleanup other lines by removing 
"\s*# generated" from every line.

It seems if you are trying to generate a good looking configuration file, that 
you would already have problems with indentation of items that return 
multiple lines (I guess you could pass them to | indent ).

I can see the benefit of what you are proposing because I have had similar 
situations, but in almost all of them my work around was to chomp everything 
- but then include the proper indentation in the text returned by TAG (if 
any).

I'm sure this isn't quite what you were looking for, but I'd thought I'd chip 
in my 2 cents.

Paul

> Here's another approach to my request:
>
> The basic idea is perhaps the opposite of the recent discussion.
> My goal is *minimal* "chomping" , namely:
>  - If the white space is part of the text, keep it.
>  - But if a blank line was generated entirely by the TT markup, drop it.
>
> Most important in this is that text that originated from separate lines
> should remain on separate lines.  The motivation is the use of TT to
> generate Apache configurations that are generated centrally and distributed
> to the live Apache servers:
>  - I have to be careful about joining lines because line breaks matter
>     in the application.
>  - I want to keep indentation and intentional blank lines, while discarding
>     spurious blank lines, because that makes the output file easier to
>     eye-ball, which I occasionally do in addition to feeding the file
>     to Apache.
>
> It seems to me that CHOMPing operates at a token level, while what I
> have in mind is more line-oriented:
>  (1) If the source line is empty or all white-space, keep it.
>  (2) If the expanded line is empty or all white-space, but the source
>      was not (ie contained TT markup), drop it.
>  (3) Keep everything else as is.
>
> I am now working around this by:
>   - Turning off all CHOMPing
>   - Using '#' to get as close as I can to a blank line, where I want that.
>   - Removing empty and blank lines from the final TT output
>
> My workaround cannot do exactly as I want, since a post-processor can't
> distinguish cases (1) and (2).  It would also be nice not to require
> an extra pass through the data for the post-processing.
>
> So my request boils down to an option something like
>   "NO_GENERATED_BLANK_LINES"  but preferrably with a shorter name.
>
> Does this make sense?  Is it of interest to anyone else?
>
> Thanks,
>
> -Len Weisberg
>
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