When I created an account here some five weeks ago, little did I realise just how much varied learning I would receive in such a short time...so I am asking for advice on an issue that has had me scratching my head many times over the years. How best to lay out code when quite a bit of text output is required, such as when dynamically creating a webpage, inside an indented block.

In the main body of the code I usually use an interpolating heredoc with any runtime variations defined in variables ahead of printing it all out.

my $login_text = $user_number?'logout':'login';

print<<"END_HTML";
<div>
  ...part of webpage...
<input type="button" name="log" value="$login_text" onClick="doSomethi
+ng();">
  ...more of webpage...
</div>
END_HTML
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That works and looks fine for a block of procedural code but I run into difficulties when I want to put something similar into an indented block for any reason. It could be a subroutine that is called to display a largely different page based on the query string or a significant block of content that is only shown under some conditions.

if (isAdmin($user_number)) {
    print ...some extra content...
}
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Heredocs don't work so well in these circumstances. I am using Perl 5.16 so don't get to use the print<<~"END_HTML"; syntax introduced in Perl 5.26.

This leaves a few option.
The one that most of my legacy code has is to simply put every line in a separate print statement

if (isAdmin($user_number)) {
    print "<table>\n";
    print "<tr>\n";
    print "<td class=\"someclass\" style=\"text-align:center\">Some Co
+ntent</td>\n";
    print "</tr><tr>\n<td class=\"someClass\">Restricted</td>\n" if $u
+ser_number == 20;
    print "</tr>\n";
    print "</table>";
}
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Not very pretty and quite difficult to follow as it becomes more involved, especially as more and more HTML gets added over time. So a slight improvement that I used for a short time is with qq to save having to escape the quotation marks.

   print qq[<td class="someclass" style="text-align:center">Some Conte
+nt</td>\n];
   print qq[</tr><tr>\n<td class="someClass">Restricted</td>\n] if $us
+er_number == 20;
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Slightly better - but still not very nice...

I have tried having a subroutine to strip out leading spaces but this has the disadvantage of always stripping leading spaces even when they are wanted! In this format it also strips out blank lines although this is not too tricky to solve.

#!/usr/bin/perl
use strict;

print "Content-type: text/plain\n\n";

print "Test\n\n";

sub indent {
    my $text = shift;
    $text =~ s/^\s+//gm;
    return $text;
}

if (1) {
    print indent(<<"END_TEXT");
    Here is
    some test text
    with plenty of space 
    at the start
END_TEXT
}

exit 0;
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This still requires END_TEXT to be written without an indent.

Many times I have searched for a solution and found several references to the issue but nothing offering a 'proper' solution. The topic of indentation in some form or another crops up periodically in all sorts of forms including Mandatory indenting which was interesting despite not being directly relevant.

Other than upgrading to Perl 5.26 or later, is there an elegant solution to laying out code to print a lot of text in an indented block?