SYNOPSIS

     use Text::sprintfn; # by default exports sprintfn() and printfn()
    
     # with no hash, behaves just like printf
     printfn '<%04d>', 1, 2; # <0001>
    
     # named parameter
     printfn '<%(v1)-4d>', {v1=>-2}; # <-2  >
    
     # mixed named and positional
     printfn '<%d> <%(v1)d> <%d>', {v1=>1}, 2, 3; # <2> <1> <3>
    
     # named width
     printfn "<%(v1)(v2).1f>", {v1=>3, v2=>4}; # <   3>
    
     # named precision
     printfn "<%(v1)(v2).(v2)f>", {v1=>3, v2=>4}; # <3.0000>

DESCRIPTION

    This module provides sprintfn() and printfn(), which are like sprintf()
    and printf(), with the exception that they support named parameters
    from a hash.

FUNCTIONS

 sprintfn $fmt, \%hash, ...

    If first argument after format is not a hash, sprintfn() will behave
    exactly like sprintf().

    If hash is given, sprintfn() will look for named parameters in argument
    and supply the values from the hash. Named parameters are surrounded
    with parentheses, i.e. "(NAME)". They can occur in format parameter
    index:

     %2$d        # sprintf version, take argument at index 2
     %(two)d     # $ is optional
     %(two)$d    # same

    or in width:

     %-10d       # sprintf version, use (minimum) width of 10
     %-(width)d  # like sprintf, but use width from hash key 'width'
     %(var)-(width)d  # format hash key 'var' with width from hash key 'width'

    or in precision:

     %6.2f       # sprintf version, use precision of 2 decimals
     %6.(prec)f  # like sprintf, but use precision from hash key 'prec'
     %(width).(prec)f
     %(var)(width).(prec)f

    The existence of formats using hash keys will not affect indexes of the
    rest of the argument, example:

     sprintfn "<%(v1)s> <%2$d> <%d>", {v1=>10}, 0, 1, 2; # "<10> <2> <0>"

    Like sprintf(), if format is unknown/erroneous, it will be printed
    as-is.

    There is currently no way to escape ")" in named parameter, e.g.:

     %(var containing ))s

 printfn $fmt, ...

    Equivalent to: print sprintfn($fmt, ...).

RATIONALE

    There exist other CPAN modules for string formatting with named
    parameter support. Two of such modules are String::Formatter and
    Text::Sprintf::Named. This module is far simpler to use and retains all
    of the features of Perl's sprintf() (which we like, or perhaps hate,
    but nevertheless are familiar with).

    String::Formatter requires you to create a new formatter function
    first. Text::Sprintf::Named also accordingly requires you to
    instantiate an object first. There is currently no way to mix named and
    positional parameters. And you don't get the full features of
    sprintf().

HOW IT WORKS

    Text::sprintfn works by converting the format string into sprintf
    format, i.e. replacing the named parameters like %(foo)s to something
    like %11$s.

DOWNSIDES

    Currently the main downside is speed. On my computer, sprintfn() is
    about two orders of magnitude slower than plain sprintf(). A simple
    benchmark on my PC (Core i5-2400 @ 3.1GHz):

     $ bench -MText::sprintfn -n -2 'sprintf("%s %d %d", "one", 2, 3)' 'sprintfn("%(str)s %d %d", {str=>"one"}, 2, 3)'
     Benchmarking a => sub { sprintf("%s %d %d", "one", 2, 3) }, b => sub { sprintfn("%(str)s %d %d", {str=>"one"}, 2, 3) } ...
     a: 13666654 calls (6831551/s), 2.001s (0.0001ms/call)
     b: 72461 calls (35045/s), 2.068s (0.0285ms/call)
     Fastest is a (194.9x b)

TIPS AND TRICKS

 Common mistake 1

    Writing

     %(var)

    instead of

     %(var)s

 Common mistake 2 (a bit more newbish)

    Writing

     sprintfn $format, %hash, ...;

    instead of

     sprintfn $format, \%hash, ...;

 Alternative hashes

    You have several hashes (%h1, %h2, %h3) which should be consulted for
    values. You can either merge the hash first:

     %h = (%h1, %h2, %h3); # or use some hash merging module
     printfn $format, \%h, ...;

    or create a tied hash which can consult hashes for you:

     tie %h, 'Your::Module', \%h1, \%h2, \%h3;
     printfn $format, \%h, ...;

SEE ALSO

    sprintf() section on perlfunc

    String::Formatter

    Text::Sprintf::Named

