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Date: Sat, 30 Aug 2014 14:26:43 -0700
Thread-Topic: [PHP-DEV] [RFC] Loosening heredoc/nowdoc scanner
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Subject: Re: [PHP-DEV] [RFC] Loosening heredoc/nowdoc scanner
From: rewilliams@thesba.com (Robert Williams)

If the syntax of heredocs/nowdocs is to be loosened, the biggest aspect I=
=92d like to see addressed is indentation. I can certainly see how it would=
 be nice to loosen the restrictions around the post-closing-token newline t=
o allow easier use in places like array definitions, but, I=92ve never run =
into that problem myself. I have, however, been annoyed by the indentation =
limitations, so much so that I could probably count with my fingers the num=
ber of times that I=92ve used the construct in the couple million lines of =
PHP I=92ve written =97 even though I *want* to use it about once a week. I =
just find the side-effect on code formatting, when used in a container stru=
cture (class, function, method, loop, whatever), to be more than I can hand=
le. Look at this simple example from the docs to see what I mean:

<http://php.net/manual/en/language.types.string.php#example-89>

One of the key benefits of consistent indentation is that it allows very ra=
pid visual navigation of code by nearly eliminating the need for reading un=
til you=92ve zoned in on the right section of code. To illustrate this very=
 well, just try to visually identify the code structure in this old-school =
BASIC code:

<http://www.atariarchives.org/basicgames/showpage.php?page=3D3>

That this restriction warrants italicized text inside a pink warning box in=
 the docs suggests both that lots of people bump into it and that it runs c=
ounter to the expectations of the language.

Now, perhaps I=92ve not felt constrained by the newline restriction simply =
because I so rarely get to use the construct at all because of the indentat=
ion restriction. That=92s actually probably the case. So that idea is impor=
tant to address, but I think it=92s pointless to address without also addre=
ssing indentation.

What if we could do something like this:

function foo() {
   $string =3D <<<
      THEEND
      This is the document text. Any
      whitespace appearing in a column
      that=92s before the starting token
      is automatically ignored for all
      lines.
   THEEND;

A few particulars:

* If the starting token appears immediately adjacent to the <<< sequence, t=
hen parsing is done according to existing rules (perhaps with the changes i=
n the RFC). This both maintains BC and avoids issues where more or less whi=
tespace is ignored when, for example, the variable is renamed.

* Extending the original proposal, the closing token can be indented withou=
t concern. Align it with the starting token, with the assignment line, what=
ever.

* The closing token could not appear within the text.

I=92ve not given this solution deep thought, so I=92m sure there are proble=
ms I=92m missing. But if there=92s a good solution to the indentation restr=
ictions, I think it would be a huge win. And with the AST-based parser, the=
re may be solutions that are possible now that were previously impossible, =
which makes this a good time to reconsider the problem.

--
Bob Williams
SVP, Software Development
Newtek Business Services, Inc.
=93The Small Business Authority=94
http://www.thesba.com/


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