Item8422: HERE documents as macro parameters

Implement HereDocumentSyntaxForMacros

-- MichaelTempest - 25 Jan 2010

getting a failure in unit test for PerlPlugin (just written); testcase is:

sub test_hereDoc {
    my $this = shift;
    my $t = <<'BEDRAGONS';
%PERL{<<HERE}%
my %x = ( a=>'%TOPIC%' );
$x{a} =~ s/%/x/g;
"$x{a}\n";
HERE
X
BEDRAGONS
    $t = Foswiki::Func::expandCommonVariables($t);
    $this->assert_equals("xTOPICxX", $t);
}

I get:

Expected:'xTOPICxX'
 But got:'xTOPICx

X
'

-- CrawfordCurrie - 15 Feb 2010

The expected result for the unit test is incorrect - it should be "xTOPICx\nX\n" because the %PERL call appends a newline to its result ( "$x{a}\n"; does this) and because perl here-documents including a traling newline, so there is a newline after the X.

There is still one newline too many in the actual result, though. I'll investigate.

-- MichaelTempest - 15 Feb 2010

That example should be roughly equivalent to the following:

sub test_hereDoc {
    my $this = shift;
    my $t = <<'BEDRAGONS';
%PERL{"my %x = ( a=>'xTOPICx' ); qq/$x{a}\n/;"}%
X
BEDRAGONS
    $t = Foswiki::Func::expandCommonVariables($t);
    $this->assert_equals("xTOPICxX", $t);
}

I changed the perl bit slightly because %TOPIC% would be expanded before the %PERL handler is called. However, the point of this change is so that it is clear that there is a newline between }% and X - this is the newline that I could not account for earlier.

I think the here-document processing is behaving correctly.

-- MichaelTempest - 15 Feb 2010

The placing for the %<nop>TOPIC% parameter expansion is deliberate. %PERL code blocks do not support expanded macros. But there's still an extra newline, isn't there? As it says in HereDocumentSyntaxForMacros,

• The newlines before and after the closing string will be ignored.

so surely the newline between x and X is extra?

-- CrawfordCurrie - 16 Feb 2010

But the X is not on the same line as the %PERL.

%PERL{<<HERE}%Z
my %x = ( a=>'%TOPIC%' );
$x{a} =~ s/%/x/g;
"$x{a}\n";
HERE
X

should expand to

xTOPICx
Z
X

The newline between x and Z comes from the perl. The newline between Z and X is the newline that follows after Z.

-- MichaelTempest - 16 Feb 2010

I agree about the newline from the perl (and I removed it in the test) but I refer you back to HereDocumentSyntaxForMacros:

• The newline at the end of any line containing a here-document (<<HERE) will be ignored. The value starts after this newline.

Thus the newline after the Z should be ignored, surely? by these two rules,

%PERL{<<HERE}%Z
my %x = ( a=>'%TOPIC%' );
$x{a} =~ s/%/x/g;
"$x{a}";
HERE
X

should expand to

ZxTOPICxX

should it not? Similarly if there are multiple heredocs on the same line:

A%IF{"cond" then=<<ELSE else=<<ENDIF}%B
will generate
ELSE
spurious newlines
ENDIF
C

if "cond" is true, I'd expect that to expand to:

ABwill generateC

and if "cond" is false,

ABspurious newlinesC

-- CrawfordCurrie - 16 Feb 2010

I re-read HereDocumentSyntaxForMacros and I accept your point that there is one newline too many.

I don't accept that the macro result should appear after text on the same line. Your "If it takes three men to dig a hole" example says otherwise.

-- MichaelTempest - 16 Feb 2010

The proposal was not accepted, so I am reverting this change.

-- MichaelTempest - 23 Feb 2010

Closing task.

-- MichaelTempest - 19 Apr 2010

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