Re: [Vala] Simple filewalker code. Comments?

[Al Thomas <astavale yahoo co uk>]

> From: Charles Hixson <charleshixsn earthlink net>
> Sent: Tuesday, 28 July 2015, 1:40
> Subject: Re: [Vala] Simple filewalker code.  Comments?
>
> Well, part of what I was looking for was stylistic pointers.  

The Wiki Vala hacking page has a style guide:
https://wiki.gnome.org/Projects/Vala/Hacking#Coding_Style
and Elementary OS write their apps in Vala and they seem 
to be using similar:
https://elementary.io/docs/code/reference#code-style
Although Yorba take a different approach:
https://wiki.gnome.org/Apps/Geary/CodingConventions

That's code formatting style, but also Vala is seen
generally as an object oriented language so you want
to be thinking about classes and interfaces. Starting to
get an understanding of design patterns by the so-called 
Gang of Four and also the SOLID principles helped me. 


> This is > the first thing I've written in vala.  Partially, the find command is 
> less than optimal because I want to include the code within another 
> program.  

I use find and it took a while for me to get to grips with it
so I thought I would share a tip based on what I use.


> Many languages include a simple filewalking approach, and I 
> was somewhat surprised that I couldn't find one within vala, so 
> partially I was looking for a pointer to a library that I had overlooked.


That's interesting, for low level stuff GLib is often the firstplace to look. The best I could find was this 
StackOverflow answer
http://stackoverflow.com/questions/2217519/how-to-walk-a-directory-in-c
One answer pointed to GFileEnumerator. Code examples on Valadoc:
http://valadoc.org/#!api=gio-2.0/GLib.FileEnumerator
but not recursive from what I can see.



> And partially I was looking for pointers as to where the community > recommended that beginners post code 
> and look for tips.
>
> I haven't been really pleased by the documentation of vala that I could 
> find, so I was hoping that there was someplace better than the mailing 
> list...and a bit over 24 hours for the first response isn't 
> encouraging.  OTOH, the civil response *is* encouraging.  ValaDoc is 
> greatly improved over the last time I investigated vala, but many things 
> still seem to assume that you are coming from a background of C 
> coding...and that you remember the C libraries.  My most recent 
> background is Python and D, so I'm often left in confusion until I dig 
> back deeper...which slows everything down.  


You could try StackOverflow:
http://stackoverflow.com/questions/tagged/vala

One of Vala's key points is its strong compatibility
with C. This enables a lot of libraries to be used in
a modern object oriented way without having to rewrite
the libraries. This does mean though you may have to start
a search with how something is done in C, often GLib, 
and then see if their is a Vala translation.


Being able to recognise some basic C interfaces has a
lot less cognitive load that trying to write good, 
scalable code in C.

As to response times that is a function of the number
of people you are addressing and whether your question
piques their interest. The larger the community the more
chance of getting someone's interest and they will then
take the time to write a response. Vala certainly has a 
smaller community than Python.







> On 07/27/2015 12:57 PM, Al Thomas wrote:
> > >  From: Charles Hixson <charleshixsn earthlink net>
> >
> > >  Sent: Sunday, 26 July 2015, 21:09
> > >  Subject: [Vala] Simple filewalker code.  Comments?
> > >
> > >  T his is working filewalker code, but I'm hoping someone will tell 
> me if
> > >  this is the correct approach.
> >  "correctness" depends on your criteria. You say it works so it is 
> correct.
> >  If on the other hand you want to be productive. Why reinvent the wheel?
> >  Why not just use something like the 'find' command line tool, e.g.
> >  find ./ -type d -exec du --human-readable '{}' \;
> >  will apply the disk usage command to each file in the current directory.
> >  It is a trivial example that just shows how much space each file takes up.
> >
> >  If you want to create a program with a bit more flexibility. Create a
> >  list of file paths in the first step. Then apply a filter function
> >  to each path, so you would use this to remove directories and then
> >  another filter function to remove symlinks, as per your current program.
> >  This allows you to add other filters later.
> >  Once you have a good list iterate over it and call your function, or 
> functions
> >  if you add more in future, with the file path as the parameter.
> >
> >  For a list exmaple see:
> >  https://wiki.gnome.org/Projects/Vala/GeeSamples
> >
> >  All the best with it,
> >
> >  Al
> >  _______________________________________________
> >  vala-list mailing list
> >  vala-list gnome org
> >  https://mail.gnome.org/mailman/listinfo/vala-list