I'm trying to highlight some pseudocode lines, and I'm using this solution pseudocode block. However, I've not understood the following new command:

    \tikz[remember picture with id=#1]
    \draw[line width=1pt,fill=\fillcol,rectangle,rounded corners]
    (pic cs:#1) ++(8.2,-.1) rectangle (-3.4,-.1);

What's mean the symbols <> in front of \newcommand?

Moreover, I'd like to pass the color to fill the rectangle as parameter for the \boxto command. In the posted solution, the color is defined as a command \fillcol How to do this change? Could someone help me?


  • 4
    <> is beamer class syntax which allows blocks of text to appear in different layers specified by for example <2> – David Carlisle Jan 25 '17 at 18:23
  • 1
    If you don't use beamer you can drop <> and must drop \only#2. – user31729 Jan 25 '17 at 18:37
  • I'm using a beamer template. – tnas Jan 25 '17 at 18:40

Just for quickness: I did not copy over unnecessary code from the linked question, i.e. I disabled the pic coordinate system and the tikz remember picture with id=#1 style.

The beamer class adds a new version of \newcommand, making it possible to generate commands with overlay specification, with

\newcommand<>{\cmdname}[number of args]{%...

% rest of code

Important to know is that the overlay specification is inside and that the command in fact has one more argument than specified, i.e. in the example, there are 3 arguments. The third one is meant for the overlay, so the last argument is always 'hidden', but can be accessed.

Please note, that the pointed brackets <1> belong to the last argument, that's how \only#3 works then.

For more on this see section 9.6 of the current beamer documentation.



  \tikz%[remember picture with id=#1]
  \draw[line width=1pt,fill=#2,rectangle,rounded corners] (1,1) rectangle (2,2);


\begin{frame}{Foo frame}


  • It works almost perfectly. There is just one problem: when I use \boxto<2>{1}{red} the second box is not displayed. So, I must to call \boxto<1>{1}{green} and \boxto<1>{1}{red}. In this case, the two boxes are displayed. Anyway, thank you so much! – tnas Jan 25 '17 at 18:58
  • 1
    @tnas a command with <2> will not be displayed originally, that is the meaning of the overlay, it will appear in the second layer if you advance the presentation. – David Carlisle Jan 25 '17 at 20:02
  • @tnas: My example was simplified because I did not want to copy the code from the linked question just in order to show how the <> syntax works for beamer's \newcommand – user31729 Jan 25 '17 at 22:30

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