Using array refs to interpolate a function itno a string?

chorg has asked for the wisdom of the Perl Monks concerning the following question:

Hey Howdy y'all,

I want to interpolate a function result into a string.

# f($x) returns a value
# I want to print this string
print "Listen f($x), I'll call the organ bank if you dont stop";
[download]

Now, I've seen a way to do this using anonymous array refs, but I can't remember where. Anyone? I think it's somewhere in the Camel, but my frenzied flipping has netted me no success. Anyone?
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Comment on Using array refs to interpolate a function itno a string? Download Code

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Re: Using array refs to interpolate a function itno a string? by chipmunk (Parson) on Dec 13, 2000 at 20:17 UTC
Here's what you're looking for: `print "Listen @{[ f($x) ]}, I'll call the organ bank if you don't stop";` The @{} gets you interpolation, and the [ ] creates an array ref that is dereferenced by @{}. You can also use a scalar ref, but it doesn't look quite as nice: `print "Listen ${\( f($x) )}, I'll call the organ bank if you don't stop";` Another nice way to get interpolation is with MJD's Interpolation module, which uses a tied hash that returns the key: `print "Listen $P{ f($x) }, I'll call the organ bank if you don't stop";` The nice thing about this module is that the tied hash can do formatting on the key before returning it, like adding commas to numbers.	[reply] [d/l] [select]
Re: Using array refs to interpolate a function itno a string? by jptxs (Curate) on Dec 13, 2000 at 20:09 UTC
print takes a list so you could make life easy by: `use strict; use warnings; sub f { $_[0] = $_[0] . '_modified' } my $x = 'value'; print 'Here is the modified value ', f($x), '. Print is a list, eh?', + "\n\n"; __END__ jptxs:/home/jptxs $ perl functionPrint Here is the modified value value_modified. Print is a list, eh? jptxs:/home/jptxs $` [download] Can't say I've ever used array refs to interpolate functions into strings - I always do something like the above. But I'm sure some other monk would know. `"A man's maturity -- consists in having found again the seriousness on +e had as a child, at play." --Nietzsch +e` [download]	[reply] [d/l] [select]
Re: Using array refs to interpolate a function itno a string? by kilinrax (Deacon) on Dec 13, 2000 at 20:11 UTC
Try wrapping the function in '`@{[ ... ]}`': `perl -e 'print qq(time: @{[scalar localtime]});'` [download]	[reply] [d/l]
Re: Using array refs to interpolate a function itno a string? by Dominus (Parson) on Dec 14, 2000 at 09:10 UTC
An alternative solution that is cooler in some ways is available with the `Interpolation` module that you can get from CPAN.	[reply]
Re: Using array refs to interpolate a function itno a string? by repson (Chaplain) on Dec 14, 2000 at 10:59 UTC
Personally I don't think interpolation is the solution here. I think interpolation is mostly useful where it makes a string clearer: `print "Hello " . $name . ".\n"; # not bad print "Hello ", $name, ".\n"; # hope no-one set $, print "Hello $name.\n"; # nice and clear print "Hello " . f($x) . ".\n"; # this is usually what I like print "Hello ", f($x), ".\n"; # has the advantage of print a list +of return values from the function without needing join (which is goo +d and bad) print "Hello @{[ f($x) ]}.\n"; # feel free to sit and stare inexper +ienced Perlers and maintainers` [download] In the first case interpolation is nice, but in the second a list or concatenation is a little clearer. And anyway the early stages of complimation seperate variables from strings (look using `perl -MO=Deparse foo.pl` if you don't belive me).	[reply] [d/l]


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