How do I create a binary stream

Hi

I'm checking some of the mooc code in Pharo 70.

The Pharo 50/60 version is

PNGReadWriter createAFormFrom: 'Sprites.png' asFileReference
binaryReadStream upToEnd

I came up with

PNGReadWriter formFromStream: (File named: 'Sprites.png') readStream

And we can also have

PNGReadWriter formFromStream: 'Sprites.png' asFileReference binaryReadStream

I will add this in the comment of the formFromStream: method.

Stef

Hi Stef,

On Sun, 11 Nov 2018 at 10:04, Stephane Ducasse <[hidden email]> wrote:
FileReference is the normal public interface to the file system, while
File is a low level API that is only used in limited circumstances,
e.g. bootstrapping when FileSystem isn't yet available.

Most users shouldn't have to worry about File, so I'd leave it out as
an example.

Cheers,
Alistair

I met that situation too with P7. It occurred to me that the precise
need of #binaryReadStream message vanished.

Hilaire

Le 11/11/2018 à 10:03, Stephane Ducasse a écrit : --
Dr. Geo
http://drgeo.eu

> On 11 Nov 2018, at 10:59, Hilaire <[hidden email]> wrote:
>
> I met that situation too with P7. It occurred to me that the precise
> need of #binaryReadStream message vanished.

I don't understand what you are saying.

Like Alistair says, FileReference is the public interface. The messages to open streams are

 #readStream
 #writeStream

for text streams (utf8 character encoded) and

 #binaryReadStream
 #binaryWriteStream

for raw unencoded binary streams. In most cases, it is better to use the #xDo: variant. It is no longer possible to switch streams using #binary.

In P7, I have to change the code to load PNG image, and I end up not
using binary alternative...

Le 11/11/2018 à 11:18, Sven Van Caekenberghe a écrit :
> I don't understand what you are saying.

--
Dr. Geo
http://drgeo.eu

So how do you load you PNG's then in P7 ?

Confusion from my part (it was 6 months ago), I have to use
#binaryReadStream to load PNG preview, and utf-8 based file (I was not
doing this distinction previously).

I changed the code in P7 in several part as it broke and it was confusing.

https://bazaar.launchpad.net/~drgeo-developers/drgeo/trunk/revision/608#src/DrGeoII-Core/DrGeoXml.class.st

Le 11/11/2018 à 11:41, Sven Van Caekenberghe a écrit :
> So how do you load you PNG's then in P7 ?

--
Dr. Geo
http://drgeo.eu

I filled a bug ticket about the change:

https://bugs.launchpad.net/drgeo/+bug/1780820

--
Dr. Geo
http://drgeo.eu

> On 11 Nov 2018, at 12:24, Hilaire <[hidden email]> wrote:
>
> Confusion from my part (it was 6 months ago), I have to use
> #binaryReadStream to load PNG preview, and utf-8 based file (I was not
> doing this distinction previously).
>
> I changed the code in P7 in several part as it broke and it was confusing.

API changes are always annoying, but splitting reading and writing as well as binary and character streams is a clear improvement overall.

> On 11 Nov 2018, at 10:29, Alistair Grant <[hidden email]> wrote:
>
> File is a low level API that is only used in limited circumstances,
> e.g. bootstrapping when FileSystem isn't yet available.

Another reason not to use File is because it is slower as it is unbuffered.

For the following file

$ file test.png
test.png: PNG image data, 950 x 936, 8-bit/color RGBA, non-interlaced

$ ls -la test.png
-rw-r--r--@ 1 sven  staff  241773 Nov 11 13:39 test.png

I get

[ ImageReadWriter formFromFileNamed: 'test.png' ] bench.
 "'8.725 per second'"

[ ImageReadWriter formFromStream: 'test.png' asFileReference binaryReadStream ] bench.
 "'8.914 per second'"

[ ImageReadWriter formFromStream: (File named: 'test.png') readStream ] bench.
 "'6.023 per second'"

By preventing the auto detection of the type and the subclass lookup, we can improve a little bit more.

[ PNGReadWriter formFromStream: 'test.png' asFileReference binaryReadStream ] bench.
 "'9.113 per second'"

Sven

I am quite happy with the new FileReference API.

Le 11/11/2018 à 13:51, Sven Van Caekenberghe a écrit :
> API changes are always annoying, but splitting reading and writing as well as binary and character streams is a clear improvement overall.
>
--
Dr. Geo
http://drgeo.eu

Thanks you all for the discussion.
We should improve the comment of File and probably the one of FileReference.
Tx Sven for the improvement of the comment of ImageReadWriter.

Good comments are so important!
We underestimate their impact.

S
On Sun, Nov 11, 2018 at 2:10 PM Hilaire <[hidden email]> wrote: