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Re: [photran] refactoring suggestion
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Bob,
I don't understand much of what you were writing. I am just a user and
have no development knowledge, but maybe my feedback is useful, although
I am probably wrong on several points.
First, but not so importantly, to me, the starred bullet-points in your
citation don't seem to be excluding each other, so I don't get them, but
never mind. More importantly, tabs often don't appear at the beginning
of a line, but in the middle of the code within a line, e.g. to align
the '=' (or any other sign) among several lines, or to quickly move an
end-of-line comment a bit to the right and have it also aligned with
other comments.
I thought that tabs are somehow clearly defined in a source (or text)
file, because independent of which editor I use, it always recognizes
them, although for some reason, the lines are often not aligned anymore
(maybe it's editor-specific how to interpret them, like the 5 or 6
spaces you mentioned). I imagined the refactoring pretty simple (and
still quite effective): replace every tab with 'x' spaces. That should
work for the cases I outlined, and should work independent of the editor
(and it's interpretation). Again, I am only a user and might be very wrong.
Thanks for your efforts.
Daniel
On 11/08/2010 05:01 AM, Bob Apthorpe wrote:
Hi,
On 11/7/2010 5:11 PM, Michel DEVEL wrote:
Le 07/11/2010 16:48, Daniel Harenberg a écrit :
Hi,
some time ago somebody on this list asked for refactoring suggestions
so that he could give it as an assignment to students. I couldn't find
that email in the Photran mailing list archives, so maybe somebody can
pick this up or forward.
The following refactoring idea seems useful and easy to implement
(please let me know if it already exists):
Replace all tabs with ('x') spaces in current file / project (and
maybe also other way around). The integer x is optional.
The reason is that - as far as I know - tab formatting is a
non-standard extension in Fortran 95 (I think it has been included in
Fortran 2003). Also, tab formatting can look different (and even
messy) when you open the same file in different editors. Nonetheless,
much legacy code does have a lot of tabs.
Dear photran developers,
I also vote for this one because I have quite a lot of Compaq Visual
Fortran legacy code that include tabs that I would like to convert to
spaces.
Thanks Daniel for requesting it.
A far-too-brief Google search turned up the following interpretation of
tabs in source code:
From
http://www.nd.edu/~hpcc/solaris_opt/SUNWspro.forte6u1/WS6U1/lib/locale/C/html/manuals/fortran/user_guide/C_f95.html
"If a tab is the first nonblank character, then:
* If the character after the tab is anything other than a nonzero digit,
then the text following the tab is an initial line.
* If there is a nonzero digit after the first tab, the line is a
continuation line. The text following the nonzero digit is the next part
of the statement."
The upshot is that leading tabs are either 5 or 6 spaces, depending on
if a continuation character is detected. Heuristically, that's probably
either a digit or an '&'. Someone with a lot more varied source code
than I have available may want to scan it because this may take some
investigation to set sane defaults. If anything, it needs to be
configurable.
As an aside, I've written some naive refactoring code in perl to address
this sort of problem, primarily using regular expressions and a little
logic code. I've delved into Photran's refactoring code and still have
some trouble rectifying my line-by-line text processing approach with
the much-more-flexible-for-most-refactorings AST approach. Is there a
place for the regex-based approach for refactorings? The tabs-to-spaces
refactoring seems to fall in the cracks between something suited to AST
modification vs a regex. The AST approach is definitely preferable for
really interesting automatic code changes but IMO the learning curve is
a lot steeper.
-- Bob
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