The bbold
package issues:
\DeclareMathAlphabet{\mathbb}{U}{bbold}{m}{n}
But this only makes \mathbb
have any effect on so-called variable family type math things, like letters. Things like +
, (
, )
are not by default of variable family type, hence they don't react to it.
\documentclass{article}
\usepackage{bbold}
\usepackage{mathastext}
\MTnonlettersobeymathxx
\begin{document}
Mathbb: $\mathbb{+)()}$
Textbb: \textbb{+)()}
\end{document}

However this will have other effects. Check the mathastext
doc how to turn this on also in subdued mode if at all possible.
You can load mathastext
in subdued mode. Then you need to move the activation of non-letters to after begin document.
\documentclass{article}
\usepackage{bbold}
\usepackage[subdued, defaultmathsizes, defaultimath, nohbar]{mathastext}
\begin{document}
\MTnonlettersobeymathxx
Mathbb: $\mathbb{+)()}$
Textbb: \textbb{+)()}
\end{document}
The impact of mathastext
is then kept to a minimal level (but adding basic
option would turn off the effect of \MTnonlettersobeymathxx
on symbols).
For full details, please refer to Extended scope of the math alphabets commands section in mathastext documentation. In particular, the operators get correct spacing, when everything is inside \mathbb
argument :
Examples to show spacing: (only second case gets it wrong)
\[a+b\]
\[a\mathbb{+}b\]
\[a\mathbb{{}+{}}b\]
\[\mathbb{a+b}\]
