I want to build a package that can optionally typeset line in double-space. Something like this:

% actual functional codes

Then I can use the package in this way:


So that all line will be typeset in double-space. If I omit that optional argument in the preamble, then all line will be typeset in single-space.

  • Welcome to TeX.sx! Apr 4, 2013 at 6:57
  • That sounds like a class (design) not package (functionality) thing
    – Joseph Wright
    Apr 4, 2013 at 7:07
  • Is the keyval part here important, and are you going to have several keyval option? If you only have one, 'faking' keyval may be the easiest approach.
    – Joseph Wright
    Apr 4, 2013 at 7:15

1 Answer 1


Here is a basic implementation, following the guide LaTeX 2e for class and package writers (section 4.3 Option declaration, p 18):

enter image description here

\usepackage{filecontents}% http://ctan.org/pkg/filecontents


Here is some

text in two paragraphs.

The package mypackage.sty declares an option doublespace which sets the condition \@doublespacetrue. If this is set to true, it \RequiresPackage{setspace} and sets \doublespacing.

  • Great! It's exactly what I want. A nice template for optional arguments. Apr 4, 2013 at 7:18

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