=head1 DESCRIPTION
Perl has a mechanism to help you generate simple reports and charts. To
-facilitate this, Perl helps you lay out your output page in your code in a
-fashion that's close to how it will look when it's printed. It can keep
-track of things like how many lines on a page, what page you're, when to
-print page headers, etc. The keywords used are borrowed from FORTRAN:
+facilitate this, Perl helps you code up your output page
+close to how it will look when it's printed. It can keep
+track of things like how many lines on a page, what page you're on, when to
+print page headers, etc. Keywords are borrowed from FORTRAN:
format() to declare and write() to execute; see their entries in
-L<manfunc>. Fortunately, the layout is much more legible, more like
+L<perlfunc>. Fortunately, the layout is much more legible, more like
BASIC's PRINT USING statement. Think of it as a poor man's nroff(1).
Formats, like packages and subroutines, are declared rather than executed,
$FORMAT_LINE_BREAK_CHARACTERS if you're using the English module) to a
list of the desired characters.
-Since use of caret fields can produce variable length records. If the text
+Using caret fields can produce variable length records. If the text
to be formatted is short, you can suppress blank lines by putting a
"~" (tilde) character anywhere in the line. The tilde will be translated
to a space upon output. If you put a second tilde contiguous to the
and the current top of form format name is in C<$^> ($FORMAT_TOP_NAME).
The current output page number is stored in C<$%> ($FORMAT_PAGE_NUMBER),
and the number of lines on the page is in C<$=> ($FORMAT_LINES_PER_PAGE).
-Whether to autoflush output on this handle is stored in $<$|>
+Whether to autoflush output on this handle is stored in C<$|>
($OUTPUT_AUTOFLUSH). The string output before each top of page (except
the first) is stored in C<$^L> ($FORMAT_FORMFEED). These variables are
set on a per-filehandle basis, so you'll need to select() into a different
=head1 NOTES
-Since the values line may contain arbitrary expression (for at fields,
-not caret fields), you can farm out any more sophisticated processing
+Since the values line may contain arbitrary expressions (for at fields,
+not caret fields), you can farm out more sophisticated processing
to other functions, like sprintf() or one of your own. For example:
format Ident =
Or to make an swrite() subroutine which is to write() what sprintf()
is to printf(), do this:
- use English;
use Carp;
sub swrite {
- croak "usage: swrite PICTURE ARGS" unless @ARG;
- local($ACCUMULATOR);
- formline(@ARG);
- return $ACCUMULATOR;
+ croak "usage: swrite PICTURE ARGS" unless @_;
+ my $format = shift;
+ $^A = "";
+ formline($format,@_);
+ return $^A;
}
$string = swrite(<<'END', 1, 2, 3);
=head1 WARNING
-During the execution of a format, only global variables are visible,
-or dynamically-scoped ones declared with local(). Lexically scoped
-variables declared with my() are I<NOT> available, as they are not
-considered to reside in the same lexical scope as the format.
+Lexical variables (declared with "my") are not visible within a
+format unless the format is declared within the scope of the lexical
+variable. (They weren't visible at all before version 5.001.) Furthermore,
+lexical aliases will not be compiled correctly: see
+L<perlfunc/my> for other issues.
projects / p5sagit/p5-mst-13.2.git / blobdiff