I am working with a custom class provided by my university for the typesetting of thesis. The class automatically includes BibTex references in the document. I want to modify the class to make it work with BibLaTex. In the class, the .bib file path is passed from the document to the class via a command. The problem is that BibLaTeX command addbibresource{} cannot process a variable as its input. See the MWE below for more details.

Is there a command I can use to expand the variable before it is processed by addbibresource{}?

MWE

Main document

documentclass{test}

usepackage[T1]{fontenc}

usepackage[utf8]{inputenc}

usepackage{csquotes}



ConfigurationDocument{fichiers-references = {references.bib}}



begin{document}

cite{franssila_introduction_2010}

printbibliography

end{document}

test.cls

RequirePackage{expl3}

ProvidesExplClass{test}{2018/09/26}{2.0}{MWE}



tl_new:N g_fichiers_references_tl



LoadClass[letterpaper,12pt]{book}

RequirePackage{xparse,etoolbox}

RequirePackage[backend=biber, style=ieee, citestyle=ieee, url=false]{biblatex}



DeclareDocumentCommand ConfigurationDocument { m }

{ keys_set:nn { udes-genie-these } { #1 } }



keys_define:nn {udes-genie-these}

{

    fichiers-references .tl_gset:N = g_fichiers_references_tl,

    fichiers-references .value_required:n = true,

}



addbibresource{g_fichiers_references_tl}

references.bib

@book{franssila_introduction_2010,

        location = {Chichester, {UK}},

        edition = {2e édition},

        title = {Introduction to microfabrication},

        publisher = {Wiley},

        author = {Franssila, Sami},

        date = {2010}

    }

Error message

! Undefined control sequence.

<argument> g 

              _fichiers_references_tl

l.21 addbibresource{g_fichiers_references_tl}

I suggest using a clist for your references instead of a tl variable.

Then you can use clist_map_function:NN g_fichiers_references_clist addbibresource inside ConfigurationDocument to add each bibliography resource.

This has the advantage that you can add multiple references in the same key:

ConfigurationDocument{fichiers-references = {references.bib, biblatex-exmaples.bib}}

So test.cls becomes:

RequirePackage{expl3}

ProvidesExplClass{test}{2018/09/26}{2.0}{MWE}



clist_new:N g_fichiers_references_clist



LoadClass[letterpaper,12pt]{book}

RequirePackage{xparse}

RequirePackage[backend=biber, style=ieee, citestyle=ieee, url=false]{biblatex}



DeclareDocumentCommand ConfigurationDocument { m }

{

  keys_set:nn { udes-genie-these } { #1 }

  clist_map_function:NN g_fichiers_references_clist addbibresource

}



keys_define:nn {udes-genie-these}

{

    fichiers-references .clist_gset:N = g_fichiers_references_clist,

    fichiers-references .value_required:n = true,

}