General ⇒ expl3: arguments wrapped in brackets

[erwann]

Hi, is there a way to modify the code below such that

Code: Select all

\foo c

returns 'EMPTY' rather than (c)?

PS: When internal and external macros share similar names (here, foo), what conventions are recommended? (In TeX, @ for the internal...)

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\documentclass{article}
\usepackage{xparse}

\ExplSyntaxOn

\cs_new:Nn \Foo:n { \tl_if_empty:nTF{#1}{EMPTY}{(#1)} }

\NewDocumentCommand { \foo } { m }
{
	\Foo:n{#1}
}

\ExplSyntaxOff

\begin{document}

\foo{c} % (c)

\foo{} % EMPTY

\foo c % (c)

\end{document}

[cgnieder]

Here is a suggestion:

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\documentclass{article}
\usepackage{xparse}
     
\ExplSyntaxOn
     
\cs_new_protected:Nn \ewann_foo:n
  { \tl_if_empty:nTF {#1} {EMPTY} {(#1)} }
     
\NewDocumentCommand \foo {g}
  {
    \IfNoValueTF {#1}
      { \ewann_foo:n {} }
      { \ewann_foo:n {#1} }
  }

\ExplSyntaxOff
     
\begin{document}
     
\foo{c} % (c)

\foo{} % EMPTY
     
\foo c % (c)

\end{document}