[Cuis-dev] fix for leading tilda in DirectoryEntry, or am I going about this the wrong way?

[Juan Vuletich]

Hi Imran,

On 7/27/2023 7:50 PM, Imran Rafique via Cuis-dev wrote:
> Juan,
>
> Thanks for taking the time to point me in the right direction. Much 
> appreciated. Yes, lots I hadn't thought of.
>
> Just one question: in Cuis, do you prefer to not have specific Error 
> subclasses and just call 'self error:' ?

It is a more general idea. Anything that goes in the image has an upside 
and a downside. A benefit and a cost. The upside includes the 
functionality, the insights it may teach readers, expandability, etc. 
The downside is _not_ the time it takes to write code. That is only paid 
once. It is not the memory required. In most cases there is so much 
memory that even a couple of kb mean nothing. The real cost is the 
cognitive burden on readers. Another thing to understand and remember 
about. In Cuis we work hard to keep complexity low. That means, for 
example, avoiding new classes that don't carry their own weight. Classes 
are globals. They take room in the global namespace, and they show up 
often, no matter what you are trying to focus on. In general, classes in 
the base image are irrelevant to the problem you are working on. The 
less of them, the better. The more relevant they are, the better.

In this case, handling tilde is worth a few lines of code. But not a new 
class unless it is really needed, and even then maybe the decision would 
be not to handle tilde at all! It is not _that_ important, and any app 
can require OSProcess and handle it itself. But a couple of lines of 
code is ok, so they are in.

Other exceptions are used more often, and many programmers will prefer 
to know about them and perhaps handle them. Those are included in the 
base image.

WRT to library or application code, it is up to you, or the developers 
of the library or app. In that context they will judge what is relevant, 
and what knowledge they want to embody in the software.

Hope this makes sense to you.

Cheers,

>
> On Thu, Jul 27, 2023, 1:27 PM Juan Vuletich <juan at cuis.st 
> <mailto:juan at cuis.st>> wrote:
>
>     Hi Imran,
>
>     There are a few issues with your change set.
>     - It breaks paths like '../../stuff' .The loop was there for a reason.
>     - Even with OSProcess it is possible that the $HOME variable is
>     not defined.
>     - Holding a workaround folder in a class variable can be problematic,
>     especially if the image is saved. Or if OSProcess is loaded after
>     this.
>     It can also hide this problem for other code that asks for a folder.
>
>     I pushed instead a different implementation that addresses this
>     issues,
>     as update #5898.
>
>     To handle the situation you can do something like
>
>     [ '~/Toto' asDirectoryEntry ] on: Error do: [ :error | error
>     description
>     print. error retryUsing: '/elToto' asDirectoryEntry ]
>
>     Having the description of the error in available in a method lets you
>     validate the kind of error, to be sure.
>
>     Finally, to test base image functionality, a change set to be
>     loaded in
>     BaseImageTests is OK. If you also want to test the behavior with
>     OSProcess loaded, another test for the OSProcess package is an
>     alternative. In that test, don't forget to test that the HOME
>     variable
>     can be resolved, and do nothing if not. Otherwise the test will
>     fail in
>     some environments (I can think of Windows, but I'm sure there are
>     others
>     where HOME is not an environment variable).
>
>     Thanks,
>
>     On 7/27/2023 11:07 AM, Imran Rafique via Cuis-dev wrote:
>     > Juan&  Hernan,
>     >
>     > I **think** the attached changeset does what you wanted. I may have
>     > overcomplicated things somewhat, but in any case, its a great
>     learning
>     > experience.
>     >
>     >
>     > Gives an exception if OSProcess is not available:
>     >
>     >      '~/foo' asFileEntry.
>     >
>     >
>     > Sets a default homedir in case we cannot read environment variables:
>     >
>     >      [ '~/foo' asDirectoryEntry ] on: NeedsPackage do: [ :ex |
>     > FileIOAccessor homeDirDefault: '/home/guess'. ex retry ]
>     >
>     >
>     > BTW, whats the preferred way of including tests for changesets
>     like this?
>     >
>     > --
>     > Regards,
>     >         Imran Sher Rafique
>
>     -- 
>     Juan Vuletich
>     cuis.st <http://cuis.st>
>     github.com/jvuletich <http://github.com/jvuletich>
>     researchgate.net/profile/Juan-Vuletich
>     <http://researchgate.net/profile/Juan-Vuletich>
>     independent.academia.edu/JuanVuletich
>     <http://independent.academia.edu/JuanVuletich>
>     patents.justia.com/inventor/juan-manuel-vuletich
>     <http://patents.justia.com/inventor/juan-manuel-vuletich>
>     linkedin.com/in/juan-vuletich-75611b3
>     <http://linkedin.com/in/juan-vuletich-75611b3>
>     twitter.com/JuanVuletich <http://twitter.com/JuanVuletich>
>


-- 
Juan Vuletich
cuis.st
github.com/jvuletich
researchgate.net/profile/Juan-Vuletich
independent.academia.edu/JuanVuletich
patents.justia.com/inventor/juan-manuel-vuletich
linkedin.com/in/juan-vuletich-75611b3
twitter.com/JuanVuletich

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