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Answer: Reading Variables from a File

by Anonymous Monk
on Jan 10, 2002 at 11:14 UTC ( #137690=categorized answer: print w/replies, xml ) Need Help??

Q&A > input and output > Reading Variables from a File - Answer contributed by Anonymous Monk

Depending on how you output the data, it could be read back by using a require (or preferably eval).

# save stuff
print FILE '$myvar = ' . $myvar . ";\n";


then to red back, just eval() the file input, or require. You may also consider Data::Dumper, which takes more complex structures and converts them into strings which can be eval()'ed to retrieve the data again.

Of course, this may not be what you're looking for in a CGI environment, as this data file would have to be writable by 'nobody'... don't want to eval it if you're not sure ;)

another option would be this:

# saving
print FILE "myvar = $myvar\n";
print FILE "anothervar = $anothervar\n";

# retrieving
while (<FILE>) {
  if (/^(\w+) *= *(.+)$/) {
     ${$1} = $2;
  }
}

This is assuming anothervar and myvar are not multi-line strings. This is a little safer than a blind eval(), although it involves symbolic scalar references...

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[shmem]: but that would mean, also, to drop the "use" not allowed in expression abomination, and make use actually return something useful (as does require at the first call, accidentally)

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