String::Interpolate::RE - interpolate variables into strings using regular expressions
version 0.11
# default formulation use String::Interpolate::RE qw( strinterp ); $str = strinterp( "${Var1} $Var2", $vars, \%opts ); # import with different default options. use String::Interpolate::RE strinterp => { opts => { useENV => 0 } };
This module interpolates variables into strings using regular expression matching rather than Perl's built-in interpolation mechanism and thus hopefully does not suffer from the security problems inherent in using eval to interpolate into strings of suspect ancestry.
The default values for "strinterp"'s options were not all well thought out. String::Interpolate::RE uses Exporter::Tiny, allowing a version of "strinterp" with saner defaults to be exported. Simply specify them when importing:
use String::Interpolate::RE strinterp => { opts => { useENV => 0 } };
The subroutine may be renamed using the -as option:
-as
use String::Interpolate::RE strinterp => { -as => strinterp_noenv, opts => { useENV => 0 } }; strinterp_noenv( ... );
$str = strinterp( $template ); $str = strinterp( $template, $vars ); $str = strinterp( $template, $vars, \%opts );
Interpolate variables into a template string, returning the resultant string. The template string is scanned for tokens of the form
$VAR ${VAR}
where VAR is composed of one or more word characters (as defined by the \w Perl regular expression pattern). VAR is resolved using the optional $vars argument, which may either by a hashref (in which case VAR must be a key), or a function reference (which is passed VAR as its only argument and must return the value).
VAR
\w
$vars
If the value returned for VAR is defined, it will be interpolated into the string at that point. By default, variables which are not defined are by default left as is in the string.
The %opts parameter may be used to modify the behavior of this function. The following (case insensitive) keys are recognized:
%opts
If this flag is true, the template string may provide a sprintf compatible format which will be used to generate the interpolated value. The format should be appended to the variable name with an intervening : character, e.g.
sprintf
:
${VAR:fmt}
For example,
%var = ( foo => 3 ); print strinterp( '${foo:%03d}', \%var, { format => 1 } );
would result in
003
If true, a variable which has not been defined will result in an exception being raised. This defaults to false.
If true, a variable which has not been defined will be replaced with the empty string. This defaults to false.
If true, the %ENV hash will be searched for variables which are not defined in the passed %var hash. This defaults to true.
%ENV
%var
If true, derived values are themselves scanned for variables to interpolate. To specify a limit to the number of levels of recursions to attempt, set the recurse_limit option. Circular dependencies are caught, but just to be safe there's a limit of recursion levels specified by recurse_fail_limit, beyond which an exception is thrown.
recurse_limit
recurse_fail_limit
my %var = ( a => '$b', b => '$c', c => 'd' ); strinterp( '$a', \%var ) => '$b' strinterp( '$a', \%var, { recurse => 1 } ) => 'd' strinterp( '$a', \%var, { recurse => 1, recurse_limit => 1 } ) => '$c' strinterp( '$a', { a => '$b', b => '$a' } , { recurse => 1 } recursive interpolation loop detected with repeated interpolation of $a
The number of recursion levels to descend when recursing into a variable's value before stopping. The default is 0, which means no limit.
0
The number of recursion levels to descend when recursing into a variable's value before giving up and croaking. The default is 100. Setting this to 0 means no limit.
100
This specifies the regular expression (created with the qr operator) which will match a variable name. It defaults to qr/\w+/. Don't use :, {, or } in the regex, or things may break.
qr
qr/\w+/
{
}
undefined variable: %s
This string is thrown if the RaiseUndef option is set and the variable %s is not defined.
RaiseUndef
%s
recursive interpolation loop detected with repeated interpolation of <%s>
When resolving nested interpolated values (with the recurse option true ) a circular loop was found.
recurse
recursion fail-safe limit (%d) reached at interpolation of <%s>
The recursion fail safe limit (recurse_fail_limit) was reached while interpolating nested variable values (with the recurse option true ).
Please report any bugs or feature requests to bug-string-interpolate-re@rt.cpan.org or through the web interface at: https://rt.cpan.org/Public/Dist/Display.html?Name=String-Interpolate-RE
Source is available at
https://gitlab.com/djerius/string-interpolate-re
and may be cloned from
https://gitlab.com/djerius/string-interpolate-re.git
Diab Jerius <djerius@cpan.org>
This software is Copyright (c) 2017 by Smithsonian Astrophysical Observatory.
This is free software, licensed under:
The GNU General Public License, Version 3, June 2007
To install String::Interpolate::RE, copy and paste the appropriate command in to your terminal.
cpanm
cpanm String::Interpolate::RE
CPAN shell
perl -MCPAN -e shell install String::Interpolate::RE
For more information on module installation, please visit the detailed CPAN module installation guide.