FAQ 4.22 How do I expand function calls in a string?

This message is one of several periodic postings to comp.lang.perl.misc
intended to make it easier for perl programmers to find answers to
common questions. The core of this message represents an excerpt
from the documentation provided with Perl.

--------------------------------------------------------------------

4.22: How do I expand function calls in a string?

(contributed by brian d foy)

This is documented in perlref, and although it's not the easiest thing
to read, it does work. In each of these examples, we call the function
inside the braces of used to dereference a reference. If we have a more
than one return value, we can construct and dereference an anonymous
array. In this case, we call the function in list context.

print "The time values are @{ [localtime] }.\n";

If we want to call the function in scalar context, we have to do a bit
more work. We can really have any code we like inside the braces, so we
simply have to end with the scalar reference, although how you do that
is up to you, and you can use code inside the braces.

print "The time is ${\(scalar localtime)}.\n"

print "The time is ${ my $x = localtime; \$x }.\n";

If your function already returns a reference, you don't need to create
the reference yourself.

sub timestamp { my $t = localtime; \$t }

print "The time is ${ timestamp() }.\n";

In most cases, it is probably easier to simply use string concatenation,
which also forces scalar context.

print "The time is " . localtime . ".\n";



--------------------------------------------------------------------

Documents such as this have been called "Answers to Frequently
Asked Questions" or FAQ for short. They represent an important
part of the Usenet tradition. They serve to reduce the volume of
redundant traffic on a news group by providing quality answers to
questions that keep coming up.

If you are some how irritated by seeing these postings you are free
to ignore them or add the sender to your killfile. If you find
errors or other problems with these postings please send corrections
or comments to the posting email address or to the maintainers as
directed in the perlfaq manual page.

Note that the FAQ text posted by this server may have been modified
from that distributed in the stable Perl release. It may have been
edited to reflect the additions, changes and corrections provided
by respondents, reviewers, and critics to previous postings of
these FAQ. Complete text of these FAQ are available on request.

The perlfaq manual page contains the following copyright notice.

AUTHOR AND COPYRIGHT

Copyright (c) 1997-2002 Tom Christiansen and Nathan
Torkington, and other contributors as noted. All rights
reserved.

This posting is provided in the hope that it will be useful but
does not represent a commitment or contract of any kind on the part
of the contributers, authors or their agents.
.

Relevant Pages