Legacy scientific codes written in fortran tend to define subroutines with very long lists of arguments (in the order of several dozens). When reading and debugging such code, one often has to count all arguments to the subroutine to identify the correspondance between an argument in the subroutine definition and its counterpart in the call.

fortran-index-args helps doing this by numbering arguments and showing indexes before each argument in the list. Such indexes are just displayed on screen, but do not modify the underlying buffer.

Example (screencast):

C Subroutine definition
      SUBROUTINE MCGFLX(SUBFFI,SUBFFA,SUBSCH,CYCLIC,KPSYS,IPRINT,IPTRK,
     1           IFTRAK,IPMACR,NDIM,K,KPN,NLONG,NREG,NSOUT,NG,NGEFF,
     2           NGIND,NZON,MATALB,V,FIMEM,QFR,M,NANI,MAXI,IAAC,KRYL,
     3           ISCR,NMU,NANGL,NMAX,LC,EPSI,CAZ,CPO,ZMU,WZMU,LFORW,
     4           PACA,NFUNL,NMOD,ISGNR,KEYFLX,KEYCUR,SIGAL,LPS,REPS,EPS,
     5           ITST,NCONV,LNCONV,REBFLG,STIS,NPJJM,SOUR,FLUX,LPRISM,
     6           N2REG,N2SOU,NZP,DELU,FACSYM)
C ...
C ...
      END



C Somewhere else in the code: a call to the subroutine
C ...
         CALL MCGFLX(MCGFFI,MCGFFA,MCGDDF,CYCLIC,IBASE(KPSYS),IMPX,
     1           IPTRK,IFTRAK,IPMACR,NDIM,NFI,NUNKNO,NLONG,NBREG,NSOU,
     2           NGRP,NGEFF,IBASE(INGIND),IBASE(INZON),IBASE(MATALB),
     3           BASE(IV),FUNKNO,SUNKNO,NBMIX,NANI,MAXI,IAAC,KRYL,ISCR,
     4           NMU,NANGL,NMAX,LC,EPSI,BASE(ICAZ),BASE(ICPO),BASE(IZMU),
     5           BASE(IWZMU),LFORW,PACA,NFUNL,NMOD,IBASE(ISGNR),
     6           BASE(IKEY),IBASE(KEYCUR),BASE(ISIGAL),LPS,BASE(IREPS),
     7           BASE(IEPS),IBASE(ITST),LBASE(INCONV),LNCONV,REBFLG,
     8           STIS,NPJJM,BASE(IS),BASE(IPHI),LPRISM,N2REG,N2SOU,NZP,
     9           DELU,FACSYM)
C ...

Just drop fortran-index-args.el somewhere and load it.

(load "/path/to/fortran-index-args.el")

1. place point in a subroutine arguments list
2. call M-x fia/display to display arguments indices
3. call M-x fia/cleanup to remove indices and return to the previous view of the buffer.

Alternatively, call M-x fia/toggle to toggle subroutine arguments indexing.

You might want to bind fia/toggle to a convenient key. For example:

(define-key fortran-mode-map (kbd "C-c i") 'fia/toggle)

Copyright (C) 2013 François Févotte.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.