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storeOn:/readFrom: symmetrical?

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rkitts

storeOn:/readFrom: symmetrical?

Hi. A basic question I hope someone can answer. This works:

— cut here ---

| stream aInt |

stream := (String new:20) writeStream.

aInt := 23.

(aInt storeOn:stream) = (aInt class readFrom:(stream contents))

— cut here ---

This doesn’t (generates an error):

— cut here ---

| stream aTime |

stream := (String new:20) writeStream.

aTime := Time now.

(aTime storeOn:stream) = (aTime class readFrom:(stream contents))

— cut here ---

To the question then. Assuming the second case isn’t wrong in some fashion I don’t understand, is it the case that storeOn:/readFrom: is supposed to be symmetrical for all classes? I ask it that way because there are a couple of Kernel classes where I’ve seen this to not be the case.

TIA,

—Rick

stepharo

Re: storeOn:/readFrom: symmetrical?

On 23/5/14 19:58, Rick Kitts wrote:

Hi. A basic question I hope someone can answer. This works:

— cut here ---

| stream aInt |

stream := (String new:20) writeStream.

aInt := 23.

(aInt storeOn:stream) = (aInt class readFrom:(stream contents))

— cut here ---

This doesn’t (generates an error):

— cut here ---

| stream aTime |

stream := (String new:20) writeStream.

aTime := Time now.

(aTime storeOn:stream) = (aTime class readFrom:(stream contents))

— cut here ---

To the question then. Assuming the second case isn’t wrong in some fashion I don’t understand, is it the case that storeOn:/readFrom: is supposed to be symmetrical for all classes? I ask it that way because there are a couple of Kernel classes where I’ve seen this to not be the case.

It would be nice that they get symmetric. because the goal of storeOn: is to recreate the same object.
So if you have a fix please
    - sign the license agreement
    - open a bug entry
    - publish the fix.

TIA,

—Rick

rkitts

Re: storeOn:/readFrom: symmetrical?

I wanted to take a second to close the book on this. It turns out that storeOn:/readFrom: are not supposed to be symmetrical. printOn:/readFrom: are supposed to be symmetrical.

storeOn: generates a string that can be fed into the interpreter/compiler such that when it is executed an instance that is equal to the receiver of the storeOn: message is created. I’m trying to figure out how to do that now so I can convert a bunch of questionable tests of storeOn:.

Thanks for taking the time. I probably should have RTFMed this a little better before troubling the list.

—Rick

On May 23, 2014 at 11:15:43 PM, stepharo ([hidden email]) wrote:

On 23/5/14 19:58, Rick Kitts wrote:

Hi. A basic question I hope someone can answer. This works:

— cut here ---

| stream aInt |

stream := (String new:20) writeStream.

aInt := 23.

(aInt storeOn:stream) = (aInt class readFrom:(stream contents))

— cut here ---

This doesn’t (generates an error):

— cut here ---

| stream aTime |

stream := (String new:20) writeStream.

aTime := Time now.

(aTime storeOn:stream) = (aTime class readFrom:(stream contents))

— cut here ---

To the question then. Assuming the second case isn’t wrong in some fashion I don’t understand, is it the case that storeOn:/readFrom: is supposed to be symmetrical for all classes? I ask it that way because there are a couple of Kernel classes where I’ve seen this to not be the case.

It would be nice that they get symmetric. because the goal of storeOn: is to recreate the same object.
So if you have a fix please
    - sign the license agreement
    - open a bug entry
    - publish the fix.

TIA,

—Rick

Esteban A. Maringolo

Re: storeOn:/readFrom: symmetrical?

I wouldn't rely on such symmetry.

Given the fact #printOn: is the only printing "instrumentation"
available to show objects in debuggers, inspectors, etc. Most of the
times it just shows a short representation of the object, not very
useful to recreate an instance from such short string.

Regards,

Esteban A. Maringolo

2014-05-26 14:11 GMT-03:00 Rick Kitts <[hidden email]>:

> I wanted to take a second to close the book on this. It turns out that
> storeOn:/readFrom: are not supposed to be symmetrical. printOn:/readFrom:
> are supposed to be symmetrical.
>
> storeOn: generates a string that can be fed into the interpreter/compiler
> such that when it is executed an instance that is equal to the receiver of
> the storeOn: message is created. I’m trying to figure out how to do that now
> so I can convert a bunch of questionable tests of storeOn:.
>
> Thanks for taking the time. I probably should have RTFMed this a little
> better before troubling the list.
>
> —Rick
>
> On May 23, 2014 at 11:15:43 PM, stepharo ([hidden email]) wrote:
>
>
> On 23/5/14 19:58, Rick Kitts wrote:
>
> Hi. A basic question I hope someone can answer. This works:
>
> — cut here ---
> | stream aInt |
>
> stream := (String new:20) writeStream.
> aInt := 23.
> (aInt storeOn:stream) = (aInt class readFrom:(stream contents))
>
> — cut here ---
>
> This doesn’t (generates an error):
>
> — cut here ---
> | stream aTime |
>
> stream := (String new:20) writeStream.
> aTime := Time now.
> (aTime storeOn:stream) = (aTime class readFrom:(stream contents))
>
> — cut here ---
>
> To the question then. Assuming the second case isn’t wrong in some fashion I
> don’t understand, is it the case that storeOn:/readFrom: is supposed to be
> symmetrical for all classes? I ask it that way because there are a couple of
> Kernel classes where I’ve seen this to not be the case.
>
>
>
> It would be nice that they get symmetric. because the goal of storeOn: is to
> recreate the same object.
> So if you have a fix please
> - sign the license agreement
> - open a bug entry
> - publish the fix.
>
>
> TIA,
> —Rick
>
>
>
>
>