NAME
String::Format - sprintf-like string formatting capabilities with
arbitrary format definitions
ABSTRACT
String::Format allows for sprintf-style formatting capabilities with
arbitrary format definitions
SYNOPSIS
use String::Format;
my %fruit = (
'a' => "apples",
'b' => "bannanas",
'g' => "grapefruits",
'm' => "melons",
'w' => "watermelons",
);
my $format = "I like %a, %b, and %g, but not %m or %w.";
print stringf($format, %fruit);
# prints:
# I like apples, bannanas, and grapefruits, but not melons or watermelons.
DESCRIPTION
String::Format lets you define arbitrary printf-like format sequences to
be expanded. This module would be most useful in configuration files and
reporting tools, where the results of a query need to be formatted in a
particular way. It was inspired by mutt's index_format and related
directives (see
<URL:
http://www.mutt.org/doc/manual/manual-6.html#index_format>).
FUNCTIONS
stringf
String::Format exports a single function called stringf. stringf takes
two arguments: a format string (see FORMAT STRINGS, below) and a
reference to a hash of name => value pairs. These name => value pairs
are what will be expanded in the format string.
FORMAT STRINGS
Format strings must match the following regular expression:
qr/
(% # leading '%'
(-)? # left-align, rather than right
(\d*)? # (optional) minimum field width
(?:\.(\d*))? # (optional) maximum field width
({.*?})? # (optional) stuff inside
(\S) # actual format character
)/x;
If the escape character specified does not exist in %args, then the
original string is used. The alignment, minimum width, and maximum width
options function identically to how they are defined in sprintf(3) (any
variation is a bug, and should be reported).
Note that Perl's sprintf definition is a little more liberal than the
above regex; the deviations were intentional, and all deal with numeric
formatting (the #, 0, and + leaders were specifically left out).
The value attached to the key can be a scalar value or a subroutine
reference; if it is a subroutine reference, then anything between the
'{' and '}' ($5 in the above regex) will be passed as $_[0] to the
subroutine reference. This allows for entries such as this:
%args = (
d => sub { POSIX::strftime($_[0], localtime) },
);
Which can be invoked with this format string:
"It is %{%M:%S}d right now, on %{%A, %B %e}d."
And result in (for example):
It is 17:45 right now, on Monday, February 4.
Note that since the string is passed unmolested to the subroutine
reference, and strftime would Do The Right Thing with this data, the
above format string could be written as:
"It is %{%M:%S right now, on %A, %B %e}d."
By default, the formats 'n', 't', and '%' are defined to be a newline,
tab, and '%', respectively, if they are not already defined in the
hashref of arguments that gets passed it. So we can add carriage returns
simply:
"It is %{%M:%S right now, on %A, %B %e}d.%n"
Because of how the string is parsed, the normal "\n" and "\t" are turned
into two characters each, and are not treated as a newline and tab. This
is a bug.
FACTORY METHOD
String::Format also supports a class method, named stringfactory, which
will return reference to a "primed" subroutine. stringfatory should be
passed a reference to a hash of value; the returned subroutine will use
these values as the %args hash.
my $self = Some::Groovy::Package->new($$, $<, $^T);
my %formats = (
'i' => sub { $self->id },
'd' => sub { $self->date },
's' => sub { $self->subject },
'b' => sub { $self->body },
);
my $index_format = String::Format->stringfactory(\%formats);
print $index_format->($format1);
print $index_format->($format2);
This subroutine reference can be assigned to a local symbol table entry,
and called normally, of course:
*reformat = String::Format->stringfactory(\%formats);
my $reformed = reformat($format_string);
AUTHOR
darren chamberlain <
[email protected]>
