latex-packages/packages/math/mathfont.pysty

__HEADER__(Collects several math fonts together)
%%% Store away the several (partially conflicting) fonts in internal macros

\let__PACKAGE_MACRO__(none@mathcal)\mathcal

\RequirePackage{mathrsfs}
\let__PACKAGE_MACRO__(mathrsfs@mathscr)\mathscr

\RequirePackage[mathscr]{eucal}
\let__PACKAGE_MACRO__(eucal@optionmathscr@mathscr)\mathscr

\RequirePackage{amsfonts}
\let__PACKAGE_MACRO__(amsfonts@mathfrak)\mathfrak

%%% Provide user commands to internally stored macros
\def__PACKAGE_MACRO__(restorefonts){
    \let\mathcal__PACKAGE_MACRO__(none@mathcal) % Set \mathcal to default calligrapic
    \let\mathfrak__PACKAGE_MACRO__(amsfonts@mathfrak) % Set \mathfrak to mathfrak from amsfonts
    \let\mathscr__PACKAGE_MACRO__(mathrsfs@mathscr) % Set \mathscr to mathscript from mathrsfs package
    \let\mathcat__PACKAGE_MACRO__(mathrsfs@mathscr) % Set \mathcat to mathscript from mathrsfs package
    \let\mathcalo__PACKAGE_MACRO__(eucal@optionmathscr@mathscr) % Set \mathcalo (for old calligraphic) to \mathscr from [mathscr]{eucal} package
}

\AtBeginDocument{__PACKAGE_MACRO__(restorefonts)}