Cfrgtkky

I like the flexibility in editing afforded by custom inline enumitem lists; for example:

documentclass{article}

usepackage{enumitem}



newlist{inlineitem}{itemize*}{1}

setlist[inlineitem]{       % Customize itemize* environ

    before=unskip{:},     % Colon before list

    itemjoin={{;}},        % Join with semicolons

    itemjoin*={{; and}},   % Last join has "; and "

    label={},               % No label

    after=.}                % Period at end of last item



begin{document}



    Here is some text that will have a list of

    begin{inlineitem}

        item a list item that could go first but also last

        item another list item that I'm not sure about

        item this one should go last unless I think of another one

    end{inlineitem}



    It's convenient because I can add, remove, and rearrange items without worrying about punctuation.



end{document}

I'd like to do the same thing with a non-inline list; however, enumitem's docs state that "itemjoin is ignored in vertical mode", and so it is.

Here's a possible solution that works by redefining item.
This may seem a little heavy-handed, but it is also how the itemjoin key for inline lists works.

I'm using SetEnumitemKey to define a new key, sentence, that can be supplied to any list environment that enumitem knows about.
It will append a period (.) to the last item and a semicolon (;) to every other item.

documentclass{article}



usepackage{enumitem}

SetEnumitemKey{sentence}{%

  before*={sentencelistprep{;}},

  after*={unskip.},

}



letsentenceitemjoinempty

edefsentenceitem{noexpandsentenceitemjoinunexpandedexpandafter{item}}%

newcommand*sentencelistprep[1]{%

  defsentenceitemjoin{defsentenceitemjoin{unskip#1}}%

  letitemsentenceitem

}



begin{document}



Here is an texttt{itemize} environment whose items are part of this sentence and therefore come with appropriate punctuation:

begin{itemize}[sentence]

item a list item that could go first but also last

item another list item that I'm not sure about that is long enough to span two lines

item this one should go last unless I think of another one

end{itemize}



It's convenient because I can add, remove, and rearrange items without worrying about punctuation.



end{document}

Warning: you can't use any other list environments inside one with the sentence key because the redefinition of item will also apply to those and will insert additional semicolons there as well.

(You probably wouldn't want to nest lists inside a running sentence, but if you have to you can add letsentenceitemjoinempty inside the inner list.)

Remarks

• I didn't include the colon (:) because does not feel like it is a part of the list (and not affected if items are reordered).
  If you do want the colon to automatically be inserted you can replace the value of before* above by {unskip:sentencelistprep{;}}.


• 
  

  If you don't want to have to supply the sentence key every time, you can create a custom list environment that includes it with e.g.

  
  
  

  newlist{myitemize}{itemize}{1}
  
  setlist[myitemize]{label=textbullet,sentence}
  
  

  
  



• The before and after keys overwrite sentence if supplied later, but the converse is not true because sentence uses the starred versions before* and after*.




• sentencelistprep{;}, which is called at the start of a list with sentence, does the following: it defines sentenceitemjoin asdefsentenceitemjoin{unskip;} and replaces item by a version that includes sentenceitemjoin.
  The first item therefore redefines sentenceitemjoin to unskip;, and every item after that consequently inserts a ; before it.

Here is a version that sort of reproduces a display itemize allowing for the features of an itemize*. Below is the same content using inlineitem (provided in question), displayitem and a regular itemize for comparison purposes:

Notes:

• 
  

  The color red has been added to make it easier to compare the three versions. You can replace the definition of Show with

  
  
  

  newcommand*{Show}[1]{#1}
  
  

  
  
  

  to eliminate the highlighting or simply remove all references to the Show macro.

  
  



• The "sort of" is because I wasn't able to get the vertical spacing of the very first item to match what itemize yields.

Code:

documentclass{article}

usepackage{enumitem}

usepackage{xcolor}



newcommand*{NextLine}{%

    newline

    vspace*{0.5baselineskip}%

    hspace*{dimexprlabelindent+labelwidth-labelseprelax}%

}%

newcommand*{Show}[1]{textcolor{red}{bfseries#1}}% Make it easier to see difference







newlist{inlineitem}{itemize*}{1}

setlist[inlineitem]{             % Customize itemize* environ

    before={unskipShow:},       % Colon before list

    itemjoin={{Show;}},          % Join with semicolons

    itemjoin*={{Show{; and}}},   % Last join has "; and "

    label={},                     % No label

    after=.,                      % Period at end of last item

}



newlist{displayitem}{itemize*}{1}

setlist[displayitem]{                      % Customize itemize* environ

    before={unskipShow:NextLine},        % Colon before list

    itemjoin={Show;NextLine},             % Join with semicolons

    itemjoin*={Show{; and}NextLine},      % Last join has "; and "

    label={$bullet$},                      % Label

    after={unskipShow.endgrafnoindent}, % Period at end of last item

}



pagecolor{white}

begin{document}

    noindent

    Here is some text in a verb|inlineitem|

    begin{inlineitem}

        item a list item that could go first but also last

        item another list item that I'm not sure about

        item this one should go last unless I think of another one

    end{inlineitem}

    Some text after verb|inlineitem|.



    bigskip



    noindent

    Here is the same text in a verb|displayitem|

    begin{displayitem}

        item a list item that could go first but also last

        item another list item that I'm not sure about

        item this one should go last unless I think of another one

    end{displayitem}

    Some text after verb|displayitem|.



    bigskip



   noindent

   Here is the same text in an verb|itemize|

    begin{itemize}

        item a list item that could go first but also last

        item another list item that I'm not sure about

        item this one should go last unless I think of another one

    end{itemize}

    Some text after regular verb|itemize|.

end{document}