Evaluating variables in here documents

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

Normally I only use here documents for html and I have never had any problems evaluating variables. i.e. Their value is always printed. However with the following piece of code

my $ret = $smtp->data(<<'EOM'); 
From: $email 
To: $unsubscribe 
Subject: 

EOM
[download]

$email and $unsubscribe seem to be printed instead of what is contained within them. I am sure there is a way around this, just not sure what it is.

Any help appreciated

Regards,

Gerard

Comment on Evaluating variables in here documents Download Code

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Re: Evaluating variables in here documents by Paladin (Vicar) on Jan 12, 2003 at 21:49 UTC
Since you put the EOM in single quotes, the here doc gets treated like a single quoted string (no interpolation). If you put the EOM in double quotes, it gets treated like a double quoted string. Further Explaination: The quotes you use around EOM determine how it will treat the text. Single quotes `''` treat it like a single quoted string Double quotes `""` or no quotes treat it like a double quoted string Back quotes `` treat it like commands to execute in the shell	[reply] [d/l] [select]
Re: Re: Evaluating variables in here documents by Hofmator (Curate) on Jan 13, 2003 at 07:56 UTC
Single quotes '' treat it like a single quoted string ... with small differences in handling backslashes: `my $var1 = <<'END'; \' $new \' \\ \/ END my $var2 = q/\' $new \' \\ \/ /; print $var1, $var2; # outputs \' $new \' \\ \/ \' $new \' \ /` [download] -- Hofmator	[reply] [d/l]
Re: Re: Evaluating variables in here documents by Gerard (Pilgrim) on Jan 12, 2003 at 22:19 UTC
Aha!!! ++ to you. Excellent thanks. Works like a charm.	[reply]
Re: Evaluating variables in here documents by tall_man (Parson) on Jan 12, 2003 at 22:21 UTC
You might also want to look into Text::Template, which provides a cleaner interface for filling in variables into text without having to use here documents.	[reply]
Re: Evaluating variables in here documents by osama (Scribe) on Jan 13, 2003 at 05:06 UTC
I've seen people use double quotes for everything, I personally started using double quotes only for strings with $variables, and using single quotes for everything else.	[reply]