How to renew caption command to get bold title?

Question

How to renew \caption command to make all title in bold? I do this:

\usepackage[labelfont=bf,labelsep=space]{caption}

and I get

Figure 1 caption

I need

Figure 1 caption

My try

\renewcommand{\caption}[1]{\caption{\textbf{#1}}}

doesn't work.

Answer 1

As egreg pointed out in his comment, since you are already loading the caption package, you don't need to redefine \caption; all you have to do is to use the option font=bf instead of just labelfont=bf (the latter affects the whole caption whilst the former only affects the caption label and separator); a little example:

\documentclass{article}
\usepackage[font=bf,labelsep=space]{caption}

\begin{document}

\begin{figure}
\centering
\rule{1cm}{1cm}% placeholder for `\includegraphics`
\caption{A test figure}
\label{fig:test}
\end{figure}

\end{document}

Another (but not so economic) option would have been to load caption on the following way

\usepackage[labelfont=bf,textfont=bf,labelsep=space]{caption}

Answer 2

Perhaps less flexible, you can modify \@makecaption to always print the caption in \bfseries:

\documentclass{article}
\makeatletter
% Taken from article.cls, although common to book.cls and report.cls
\long\def\@makecaption#1#2{%
  \vskip\abovecaptionskip
  \sbox\@tempboxa{\bfseries#1: #2}%
  \ifdim \wd\@tempboxa >\hsize
    \bfseries#1: #2\par
  \else
    \global \@minipagefalse
    \hb@xt@\hsize{\hfil\box\@tempboxa\hfil}%
  \fi
  \vskip\belowcaptionskip}
\makeatother
\begin{document}
\begin{figure}[ht]\caption{This is a figure caption}\end{figure}
\begin{table}[ht]\caption{This is a table caption}\end{table}
\end{document}