reassigning values to variables question
Hi All, If I have a variable of type Buf which 1000 bytes in it and I find the five bytes I want, is it faster, slower, or no difference in speed to overwrite the same variable with the five bytes? Or is it faster to put the five bytes from the first variable into a second variable? Many thanks, -T
Re: "read" options?
On 2/3/19 8:46 PM, Norman Gaywood wrote: On Mon, 4 Feb 2019 at 15:12, ToddAndMargo via perl6-users mailto:perl6-users@perl.org>> wrote: https://docs.perl6.org/routine/read Where is the list of the options this thing will take, such as :ro and :bin? Those are options for open() https://docs.perl6.org/routine/open Thank you!
Re: "read" options?
On Mon, 4 Feb 2019 at 15:12, ToddAndMargo via perl6-users < perl6-users@perl.org> wrote: > https://docs.perl6.org/routine/read > > Where is the list of the options this thing will take, such > as :ro and :bin? > > Those are options for open() https://docs.perl6.org/routine/open -- Norman Gaywood, Computer Systems Officer School of Science and Technology University of New England Armidale NSW 2351, Australia ngayw...@une.edu.au http://turing.une.edu.au/~ngaywood Phone: +61 (0)2 6773 2412 Mobile: +61 (0)4 7862 0062 Please avoid sending me Word or Power Point attachments. See http://www.gnu.org/philosophy/no-word-attachments.html
"read" options?
Hi All, https://docs.perl6.org/routine/read Where is the list of the options this thing will take, such as :ro and :bin? Many thanks, -T
Re: decode options?
On 2/3/19 4:56 PM, ToddAndMargo via perl6-users wrote:
Hi All,
Uhhh,
https://docs.perl6.org/routine/decode
role Blob
From Blob
(Blob) method decode
Defined as:
multi method decode(Blob:D: Str:D $encoding = 'UTF-8' --> Str:D)
Applies an encoding to turn the blob into a Str.
my Blob $blob = "string".encode('utf-8');
say $blob.decode('utf-8'); # OUTPUT: «string»
On malformed utf-8 .decode will throw X::AdHoc. To handle
sloppy utf-8 use utf8-c8.
where are the decode options? I only see utf-8 and utf8-c8.
Am I blind?
Many thanks,
-T
Found it and I am not blind. The Docs just stink. I would
write an RFE for this, but, the odds of them accepting it are
so close to zero that it is not worth the effort.
And what is with?
Str:D $encoding = 'UTF-8'
$encoding can accept a whole bunch of things. And
What the heck is `'UTF-8'`? It sure ain't "utf8" or
Rakudo's "utf-8".
My own docs:
https://docs.perl6.org/type/IO::Handle#___top
utf8
utf16
utf16le
utf16be
utf8-c8
iso-8859-1
windows-1251
windows-1252
windows-932
ascii
Rakudo extensions:
latin-1 (iso-8859-1)
utf-8
utf-16
Re: Fastest way to convert from a Buf to a Str?
On 2/3/19 5:26 PM, Darren Duncan wrote:
On 2019-02-02 7:22 PM, ToddAndMargo via perl6-users wrote:
I need to read a file into a buffer (NO CONVERSIONS!)
and then convert it to a string (again with no
conversions).
I think you're making an impossible request.
Don't forget that I think everywhere on this list is
a bloody genius.
If preserving exact bytes
is important, then you want to keep your data in a type that represents
a sequence of bytes, such as Blob of Buf. A Str represents a sequence
of characters, which are NOT bytes, so if you're wanting to have a Str
that is saying you don't care about the bytes. Given what you keep
saying, I'd say skip the Str and just use Buf or Blob etc full stop. --
Darren Duncan
Hi Darren,
for ( @$BinaryFile ) -> $Char { $StrFile ~= chr($Char); }
Does the trick, but it takes up to 15 seconds. Way
too slow.
I have another post looking to see if any of the other
decodes will work. So maybe...
My big issue is that the data I am looking through uses four
nuls in a row as a delimiter. If these get dropped, I
won't be able to find anything.
Your idea about just skipping Str is along the line I have
also been thinking. Brad has been helping me with "index" for
a Buf. I haven't had a shot at trying his corrections to my
code yet.
-T
Re: Fastest way to convert from a Buf to a Str?
On 2019-02-02 7:22 PM, ToddAndMargo via perl6-users wrote: I need to read a file into a buffer (NO CONVERSIONS!) and then convert it to a string (again with no conversions). I think you're making an impossible request. If preserving exact bytes is important, then you want to keep your data in a type that represents a sequence of bytes, such as Blob of Buf. A Str represents a sequence of characters, which are NOT bytes, so if you're wanting to have a Str that is saying you don't care about the bytes. Given what you keep saying, I'd say skip the Str and just use Buf or Blob etc full stop. -- Darren Duncan
decode options?
Hi All,
Uhhh,
https://docs.perl6.org/routine/decode
role Blob
From Blob
(Blob) method decode
Defined as:
multi method decode(Blob:D: Str:D $encoding = 'UTF-8' --> Str:D)
Applies an encoding to turn the blob into a Str.
my Blob $blob = "string".encode('utf-8');
say $blob.decode('utf-8'); # OUTPUT: «string»
On malformed utf-8 .decode will throw X::AdHoc. To handle
sloppy utf-8 use utf8-c8.
where are the decode options? I only see utf-8 and utf8-c8.
Am I blind?
Many thanks,
-T
Re: "index" source code?
The Rakudo Perl6 compilier is written in Perl6 (and a subset of Perl6 named NQP)
The `index` subroutines are at
https://github.com/rakudo/rakudo/blob/64c88f919841c58f5a6dffd3581770e06a8fd6a5/src/core/Cool.pm6#L276-L282
proto sub index($, $, $?, *%) {*}
multi sub index(Cool $s, Cool $needle --> Int:D) {
$s.index($needle)
}
multi sub index(Cool $s, Cool $needle, Cool $pos --> Int:D) {
$s.index($needle,$pos)
}
They basically only call the `index` and `rindex` methods
To keep from showing you all of the methods, they all coerce the value
to Str then call `index` on that.
The location of the Str.index methods is
https://github.com/rakudo/rakudo/blob/3d581c8d23e0b47fd09616a1165f84568531a4aa/src/core/Str.pm6#L255-L284
proto method index(|) {*}
multi method index(Str:D: Cool:D $needle --> Int:D) {
self.index: $needle.Str
}
multi method index(Str:D: Str:D $needle --> Int:D) {
nqp::if(
nqp::islt_i((my int $i =
nqp::index($!value,nqp::getattr($needle,Str,'$!value'))),
0
),
Nil,
nqp::p6box_i($i)
)
}
multi method index(Str:D: Cool:D $needle, Cool:D $pos --> Int:D) {
self.index: $needle.Str, $pos.Int
}
multi method index(Str:D: Str:D $needle, Int:D $pos --> Int:D) {
nqp::if(
nqp::isbig_I(nqp::decont($pos)) || nqp::islt_i($pos,0),
self!INDEX-OOR($pos),
nqp::if(
nqp::islt_i((my int $i = nqp::index(
$!value,nqp::getattr($needle,Str,'$!value'),$pos
)),0),
Nil,
nqp::p6box_i($i)
)
)
}
Note that they heavily use NQP opcodes, so you shouldn't try and copy them.
On Sun, Feb 3, 2019 at 12:35 AM ToddAndMargo via perl6-users
wrote:
>
> Hi All,
>
> Was the subroutine "index" written Perl6? If so,
> where can I view the source code?
>
> Many thanks,
> -T
Re: binary test and position?
On 2/2/19 9:29 PM, Brad Gilbert wrote:
It is also weird that you are using CamelCase for variables,
and a mixture of CamelCase and snake-case for the subroutine name.
Hi Brad,
An explanation. I do this for "maintainability".
I have been able to "type" since high school typing
class. Upper and lower are no difference in speed
to me. (I do realize that "hunt and peckers" go nuts
with upper and lower case.)
So, Camel Case tells me instantly that a variable and
sub name came from me and are not something I copied
from somewhere else (zef), or a reserved word or a
build-in sub name. There is no "Did I write this
or ...?" when I go months later to fix/add some
something.
Since I come from Modula 2, I live and breath modules.
Awful nice to be able to know at a glance if I wrote
something or I used someone else's module.
And I absolutely ADORE the way Perl 6 does their modules.
Well, importing them needs some work. They need to
restore Perl 5's functionality where you can explicitly
state which subs you are importing from a module:
use Term::ANSIColor qw ( BOLD BLUE RED GREEN RESET );
use Term::ReadKey qw ( ReadKey ReadMode );
Again, for maintainability, so I know where the blazes
something came from.
I work around the problem with my own imposed comments:
use CurlUtils;# qw[ CurlDownloadFile CurlGetWebSite
CurlGetHeader CurlExists CurlSendMail, CurlGetRedirectUrl ];
and
#`{
Interface to curl from Perl 6
To use these, place the following at the top(ish) of your program
use lib "/home/linuxutil";
use CurlUtils; # qx[ CurlDownloadFile CurlGetWebSite
CurlGetHeader CurlExists CurlSendMail ]
}
Oh ya, and I live and die in "Top Down", so I GOT TO HAVE my subs!
Perl is a "Write Only language" if you let it be.
-T
Re: Fastest way to convert from a Buf to a Str?
On 2/3/19 1:55 AM, David Warring wrote:
Are all characters in the range 0-255, ie latin-1 characters?
You could then try: my $str = $buf.decode("latin-1");
There's one potential issue if your data could contain DOS end of lines
("\r\n"), which will get translated to a single logical "\n" in the
decoded string.
- David
Hi David,
It has to be an exact match. That includes all carriage returns,
line feeds, page feeds, eofs, tabs, etc.. But thank you anyway.
:-)
-T
Re: Fastest way to convert from a Buf to a Str?
Are all characters in the range 0-255, ie latin-1 characters?
You could then try: my $str = $buf.decode("latin-1");
There's one potential issue if your data could contain DOS end of lines
("\r\n"), which will get translated to a single logical "\n" in the decoded
string.
- David
On Sun, Feb 3, 2019 at 7:16 PM Brad Gilbert wrote:
> This:
>
> for ( @$BinaryFile ) -> $Char { $StrFile ~= chr($Char); }
>
> is better written as
>
> my $StrFile = $BinaryFile.map(*.chr).reduce(* ~ *);
>
> It is also exactly equivalent to just e
>
> # if $BinaryFile is a Buf
> my $StrFile = $BinaryFile.decode('latin1');
>
> # if it isn't
> my $StrFile = Buf.new($BinaryFile).decode('latin1');
>
> If you don't otherwise need $BinaryFile
>
> my $fh = open 'test', :enc('latin1');
> my $StrFile = $fh.slurp;
>
> or
>
> my $StrFile = 'test'.IO.slurp(:enc('latin1'));
>
> ---
>
> Buf and Str used to be treated more alike, and it was very confusing.
>
> There should be more methods on Buf that work like the methods on Str,
> but that is about it.
>
> Having a string act like a buffer in Modula 2 probably works fine
> because it barely supports Unicode at all.
>
> Here is an example of why it can't work like that in Perl6:
>
> my $a = 'a';
> my $b = "\c[COMBINING ACUTE ACCENT]";
>
> my $c = $a ~ $b;
> my $d = $a.encode ~ $b.encode;
> my $e = Buf.new($a.encode) ~ Buf.new($b.encode);
>
> say $a.encode; # utf8:0x<61>
> say $b.encode; # utf8:0x
>
> say $c.encode; # utf8:0x
>
> say $d; # utf8:0x<61 CC 81>
> say $e; # Buf:0x<61 CC 81>
>
> Notice that `$c.encode` and `$d` are different even though they are
> made from the same parts.
> `$d` and `$e` are similar because they are dealing with lists of
> numbers not strings.
>
> On Sat, Feb 2, 2019 at 9:23 PM ToddAndMargo via perl6-users
> wrote:
> >
> > Hi All,
> >
> > I need to read a file into a buffer (NO CONVERSIONS!)
> > and then convert it to a string (again with no
> > conversions).
> >
> > I have been doing this:
> >
> > for ( @$BinaryFile ) -> $Char { $StrFile ~= chr($Char); }
> >
> > But it takes a bit of time. What is the fastest way to do this?
> >
> > I guess there is not a way to create/declare a variable that is
> > both Buf and Str at the same time? That would mean I did not
> > have to convert anything. I use to get away with this under
> > Module 2 all the time.
> >
> > $ p6 'my $B = Buf.new(0x66, 0x66, 0x77); $B.Str ~= "z";'
> > Cannot use a Buf as a string, but you called the Str method on it
> >in block at -e line 1
> >
> > $ p6 'my $B = Buf.new(0x66, 0x66, 0x77); Str($B) ~= "z";'
> > Cannot use a Buf as a string, but you called the Str method on it
> >in block at -e line 1
> >
> >
> > Many thanks,
> > -T
> >
> > --
> >
> > A computer without Microsoft is like
> > a chocolate cake without the mustard
> >
>
