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[squeak-dev] Rio: exceptions documentation

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CdAB63

[squeak-dev] Rio: exceptions documentation

Hello,

I had a code like:

[ aStream := CrLfFileStream new open: 'aGivenFileName' forWrite: false ]
on: FileDoesNotExistException do: [ :exception | <code ....> ].

It worked ok. But with:

[ aStream := 'aGivenFileName' asRio reader ] on:
FileDoesNotExistException do: [ :exception | <code ...> ].

things just don't work... Where I can find exceptions documentation (in
particular for Rio) ?

Besides, it seems that the atEnd message is delayed by one entry (in the
first case 1025 lines are correctly read and in the second case it goes
one line ahead in the file).

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keith1y

Re: [squeak-dev] Rio: exceptions documentation

Casimiro de Almeida Barreto wrote:

> Hello,
>
> I had a code like:
>
> [ aStream := CrLfFileStream new open: 'aGivenFileName' forWrite: false ]
> on: FileDoesNotExistException do: [ :exception | <code ....> ].
>
> It worked ok. But with:
>
> [ aStream := 'aGivenFileName' asRio reader ] on:
> FileDoesNotExistException do: [ :exception | <code ...> ].
>
> things just don't work... Where I can find exceptions documentation (in
> particular for Rio) ?
>
> Besides, it seems that the atEnd message is delayed by one entry (in the
> first case 1025 lines are correctly read and in the second case it goes
> one line ahead in the file).
>

Hello Casmiro,

great to see you using Rio. The latest version has moved away from using
"Rio" in the code and is now (for better or worse) using classes called
File/Directory.

Rio doesnt use exceptions very much at all for various reasons. It is
relatively easy to test for existence, and there are other utilities
provided.

In your case where you want a basic stream,

"returns nil if the file does not exist"
aStream := 'aGivenFileName' asFile reader.

"returns nil if the file does not exist"
data = 'aGivenFileName' asFile contents.

"The reading block is ignored if the file does not exist"
'aGivenFileName' asFile reader: [ :str | aChar := str next ].

"an explicit checks for existence are available via"
'aGivenFileName' asFile ifFileDo: [ :f | f contents ].
'aGivenFileName' asFile ifExistsDo: [ :f | f contents ].
'aGivenFileName' asFile ifAbsentDo: [ :f | f touch ].

The latest Rio is available from Universes, be prepared to replace
senders of asRio with asFile/asDirectory

thanks for the feedback, knowing the above wold you rather have
exceptions still?

best regards

Keith

Paolo Bonzini-2

[squeak-dev] Re: Rio: exceptions documentation

The naming conventions seem to be a bit inconsistent: for example, why not

> aStream := 'aGivenFileName' asFile reader.

readStream

> 'aGivenFileName' asFile reader: [ :str | aChar := str next ].

and withReadStreamDo:?

> The latest Rio is available from Universes, be prepared to replace
> senders of asRio with asFile/asDirectory

I switched from File/Directory to just File in GNU Smalltalk 3.1. It
proved to be a mess to use two classes (you can differentiate with
#entries vs. #contents). It seems a good idea in the beginning, but
when you add virtual filesystems (which Rio has IIUC) such as ZIP file
transparent access, you get code duplication all over the place.

One alternative is to have an internal class for OS access and provide
two facades, one exposing only file protocol and one exposing only
directory protocol. This is actually what GNU Smalltalk < 3.1 did. But
they have to be ready to fail anyway (e.g. if you do "'foo' asDirectory"
and someone does "'foo' asFile touch" concurrently or outside Squeak),
so IMO it is not really worth it.

Paolo

keith1y

Re: [squeak-dev] Re: Rio: exceptions documentation

The naming conventions seem to be a bit inconsistent: for example, why not

> > aStream := 'aGivenFileName' asFile reader.
>

readStream

> > 'aGivenFileName' asFile reader: [ :str | aChar := str next ].
>

and withReadStreamDo:?

Historically Rio was designed to use the message eating Null as part of its way of thinking. So typically #reader was equivalent to #readStreamOrNull. The "Null thought police" "encouraged" me to give up that idea.

Also Rio used to have adaptors, for handling different types of files, and would ask the adaptor for a file specific #reader, the adaptor would implement #readStream if appropriate, but there was/is no expectation that the reader would have to be a stream. Some filetypes were expected to have higher level readers.

The adaptor/reference pair evolved. Having moved a lot of the functionality into the file system executor, it turned out that the reference class hierarchy didnt have any code in it, so the adaptor/reference hierarchies merged. So therefore subclasses of File/Directory may be directly specialised. Having done this they could define their own interface onto their file type, so now #reader doesnt have to be generic anymore and could be changed/mirrored by readStream.

To be honest I dont really like withReadStreamDo:, I wrote the original Rio API before coding things, and designed what I wanted to see.

> I switched from File/Directory to just File in GNU Smalltalk 3.1.
In Rio the majority of the code is in File, Directory inherits and adds
methods for moving files between Directories, such as #addTree:. I like
having files represented by 'a File' and directories represented by 'a
Directory', having gone to the effort of separating them a little,
though in truth Directory would be the equivalent of your File, since it
implements everything.

Keith

CdAB63

Re: [squeak-dev] Rio: exceptions documentation

In reply to this post by keith1y

Keith Hodges escreveu:

Hello Casmiro,

great to see you using Rio. The latest version has moved away from using
"Rio" in the code and is now (for better or worse) using classes called
File/Directory.

Rio doesnt use exceptions very much at all for various reasons. It is
relatively easy to test for existence, and there are other utilities
provided.

In your case where you want a basic stream,

"returns nil if the file does not exist"
aStream := 'aGivenFileName' asFile reader.

"returns nil if the file does not exist"
data  = 'aGivenFileName' asFile contents.

"The reading block is ignored if the file does not exist"
'aGivenFileName' asFile reader: [ :str |  aChar := str next ].

"an explicit checks for existence are available via"
'aGivenFileName' asFile ifFileDo: [ :f | f contents ].
'aGivenFileName' asFile ifExistsDo: [ :f | f contents ].
'aGivenFileName' asFile ifAbsentDo: [ :f | f touch ].

The latest Rio is available from Universes, be prepared to replace
senders of asRio with asFile/asDirectory

thanks for the feedback, knowing the above wold you rather have
exceptions still?

best regards

Keith

Hello Keith,

Working in a Fedora rel 10 intel box I've had the following problem:

aStream := self myFileName asFile reader. ... [ aStream atEof ] whileFalse: [ aLine := aStream nextLine. ... ]

If the file is a text file created in Linux, then it will read only one line.
If the file is a CrLf text file (Microsoft) it will read the total number of lines plus 1.
Besides, many of the reads will be twisted (with the Cr char as part of the string).

When I do:

aStream := CrLfFileStream fileNamed: self myFileName.

Things work properly with:

aLine := aStream nextLine.

if I have a dos text file (crlf)

Obviously: aLine := nextString also fails.

How to fix the behaviour of nextLine for common Linux text files ???

Best regards,

Casimiro

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keith1y

Re: [squeak-dev] Rio: exceptions documentation

Casimiro de Almeida Barreto wrote:

> Keith Hodges escreveu:
>>
>> Hello Casmiro,
>>
>> great to see you using Rio. The latest version has moved away from using
>> "Rio" in the code and is now (for better or worse) using classes called
>> File/Directory.
>>
>> Rio doesnt use exceptions very much at all for various reasons. It is
>> relatively easy to test for existence, and there are other utilities
>> provided.
>>
>> In your case where you want a basic stream,
>>
>> "returns nil if the file does not exist"
>> aStream := 'aGivenFileName' asFile reader.
>>
>> "returns nil if the file does not exist"
>> data = 'aGivenFileName' asFile contents.
>>
>> "The reading block is ignored if the file does not exist"
>> 'aGivenFileName' asFile reader: [ :str | aChar := str next ].
>>
>> "an explicit checks for existence are available via"
>> 'aGivenFileName' asFile ifFileDo: [ :f | f contents ].
>> 'aGivenFileName' asFile ifExistsDo: [ :f | f contents ].
>> 'aGivenFileName' asFile ifAbsentDo: [ :f | f touch ].
>>
>> The latest Rio is available from Universes, be prepared to replace
>> senders of asRio with asFile/asDirectory
>>
>> thanks for the feedback, knowing the above wold you rather have
>> exceptions still?
>>
>> best regards
>>
>> Keith
>>
>>
> Hello Keith,
>
> Working in a Fedora rel 10 intel box I've had the following problem:
>
> aStream := self myFileName asFile reader.
> ...
> [ aStream atEof ] whileFalse: [
> aLine := aStream nextLine.
> ...
> ]
>
> If the file is a text file created in Linux, then it will read only
> one line.
> If the file is a CrLf text file (Microsoft) it will read the total
> number of lines plus 1.
> Besides, many of the reads will be twisted (with the Cr char as part
> of the string).
>
> When I do:
>
> aStream := CrLfFileStream fileNamed: self myFileName.
>
> Things work properly with:
>
> aLine := aStream nextLine.
>
> if I have a dos text file (crlf)
>
> Obviously: aLine := nextString also fails.
>
> How to fix the behaviour of nextLine for common Linux text files ???
>
> Best regards,
>
> Casimiro

Thanks for the feedback, I fixed this in latest.

CrLfStream has been replaced by MultiByteFileStream and this can be set
to read in various modes, it is also supposed to detect the line ending
convention. Unfortunately this was disabled by default. Rio was
explicitly telling binary streams that they were binary streams, but was
omitting to tell ascii streams to enable lineEndingdetection.

thanks for the feedback.

Keith

CdAB63

Re: [squeak-dev] Rio: exceptions documentation

Keith Hodges escreveu:

Thanks for the feedback, I fixed this in latest.

CrLfStream has been replaced by MultiByteFileStream and this can be set
to read in various modes, it is also supposed to detect the line ending
convention. Unfortunately this was disabled by default. Rio was
explicitly telling binary streams that they were binary streams, but was
omitting to tell ascii streams to enable lineEndingdetection.

thanks for the feedback.

Keith

Hello Keith,

I guess I am the one who must thank you for your prompt answers !!!
Now everything is working as should be (x := aName asFile reader. ... a := x nextLine.) both for DOS files or native unix text files.

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