# redeclare an arrow in TikZ

As you know, I'm adding more arrows to the code in this answer (maybe tomorrow). At this point, I'd like to overwrite the arrows declarations so that one can simply write -latex instead of -latex new, but TikZ gives me an error because the arrow names have already been used. Is there a way to bypass this behaviour and redefine an arrow tip?

Example of code:

\documentclass[tikz, border=1pt]{standalone}
\usepackage{tikz}

\pgfarrowsdeclare{space}{space}
{
\pgfutil@tempdima=0.88pt%
\pgfarrowsleftextend{0pt}
\pgfarrowsrightextend{\pgfutil@tempdima}
}
{}

\begin{document}
\begin{tikzpicture}
\draw [-space] (0,0) -- (1,0);
\end{tikzpicture}
\end{document}

-
I would define your arrows with unique names and then give the user the option of substituting them for the original names at the top level. – Loop Space Nov 11 '12 at 20:13
@AndrewStacey I'm following your advice. – Luigi Nov 12 '12 at 10:41
I hope that this means you're packaging your arrows into a proper package. – Loop Space Nov 12 '12 at 10:42
@AndrewStacey, I edited all the available arrow tips, except for almost 0d ones (like line caps) and implies, and I wrote to Till Tantau. Now I'm waiting for a reply. – Luigi Nov 12 '12 at 16:52

Well, it's not recommended but you can bypass the already defined? test.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows}

\makeatletter
{#3}%
}

\pgfarrowsdeclare{space}{space}
{
\pgfutil@tempdima=0.88pt%
\pgfarrowsleftextend{0pt}
\pgfarrowsrightextend{\pgfutil@tempdima}
}
{}
\makeatother

\begin{document}
\begin{tikzpicture}
\draw [-space] (0,0) -- (1,0);
\end{tikzpicture}
\end{document}

-
+1 Maybe this is the right way. I don't know if there are any collateral effects. I think I'll reactivate the "already defined" definition at the end of the code. Thanks – Luigi Nov 11 '12 at 19:21
do you think I should leave the code as is (i.e. with the latex new arrow)? – Luigi Nov 11 '12 at 19:29
@Luigi It seems that this is the only sanity check regarding the definition of the arrow so my humble opinion is that this is a risk that one can take but then again it's just me ;) – percusse Nov 11 '12 at 19:36