Building on Frederik's answer, I built myself an iteratable interface to
line reading which looks just like python. This is already pretty. :-)
I don't understand how the following works though:
next_line = fi.dis.read_line (null, null) + "\n";
return next_line!=null;
I would rather write it:
next_line = fi.dis.read_line(null,null);
if (next_line != null)
next_line = next_line + "\n"
but that gives me an error of:
iter.vala:20.29-20.44: error: Arithmetic operation not supported
for types `string' and `string'
next_line = next_line + "\n";
why? What's the difference?
Regads,
Dov
// Dov Grobgeld <[EMAIL PROTECTED]>
// This code is in the public domain.
using GLib;
class FileIter : GLib.Object, Gee.Iterable<string> {
private class Iterator<string> : GLib.Object, Gee.Iterator<string> {
weak FileIter fi {set; get; }
string next_line;
public Iterator (FileIter file_iter) {
this.fi = file_iter;
}
public bool next() {
next_line = fi.dis.read_line (null, null) + "\n";
return next_line!=null;
}
public string get() {
return next_line;
}
}
private DataInputStream dis { get; set;}
public FileIter(DataInputStream in_stream)
{
this.dis = in_stream;
}
public static FileIter? open(string filename)
{
File my_file = File.new_for_path (filename);
DataInputStream in_stream = new DataInputStream (my_file.read
(null));
return new FileIter(in_stream);
}
GLib.Type get_element_type()
{
return typeof(string);
}
Gee.Iterator<string> iterator()
{
return new Iterator<string> (this);
}
}
int main(string[] args) {
var fi = FileIter.open(args[1]);
foreach (string s in fi)
print(s);
return 0;
}
2008/6/9 Dov Grobgeld <[EMAIL PROTECTED]>:
> Ok. Thanks. I see that it is possible, though the syntax is not what I
> would call pretty...
>
> ...which made me thinking, would it be possible to write something that use
> the iterator interface for reading lines from a file? I.e. something like:
>
> File f = File.open("path");
>
> foreach (string s in f.readlines()) {
> print s;
> }
>
> What exactly is an iterator? An interface? Where is it defined?
>
> Regards,
> Dov
>
> 2008/6/8 Frederik <[EMAIL PROTECTED]>:
>
> Dov Grobgeld schrieb:
>>
>>> In my efforts to of making sure that I can do simple constructs with the
>>> language I tried to read a file line by line.
>>>
>>
>> Use GIO instead, it's part of the GLib namespace.
>>
>> http://library.gnome.org/devel/gio/stable/
>>
>> File.read () will give you a FileInputStream which you can decorate as
>> a DataInputStream, then you can read line by line.
>>
>> ------
>>
>> File my_file = File.new_for_path ("myfile.data");
>>
>> DataInputStream in_stream;
>>
>> try {
>> in_stream = new DataInputStream (my_file.read (null));
>> string line;
>> while (null != (line = in_stream.read_line (null, null))) {
>> print (line);
>> }
>> } catch (Error e) {
>> critical (e.message);
>> } finally {
>> in_stream.close (null);
>> }
>>
>> ------
>>
>> You will have to compile with "--pkg gio-2.0". Currently you will get
>> some warnings about nullable parameters, since they aren't marked yet in
>> the vapi bindings, which you can safely ignore.
>>
>>
>>
>> Frederik
>>
>> _______________________________________________
>> Vala-list mailing list
>> [email protected]
>> http://mail.gnome.org/mailman/listinfo/vala-list
>>
>
>
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