[Pharo-users] Re: (Re)storing code blocks from text strings (hopefully in STON)

Ohhh :-O ... where is the STON booklet. I would love to read it. Thanks, Offray On 4/12/20 3:24 p. m., Stéphane Ducasse wrote:

Done :)

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On 4 Dec 2020, at 21:20, Stéphane Ducasse <stephane.ducasse@inria.fr <mailto:stephane.ducasse@inria.fr>> wrote:

It looks like it is recurring  enough to be part of the Ston booklet :)

I will add it. 

S. 

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On 1 Dec 2020, at 10:54, Sven Van Caekenberghe <sven@stfx.eu <mailto:sven@stfx.eu>> wrote:

Hi Offray,

This is a recurring question. BlockClosures are way too general and powerful to be serialised. That is why serialising BlockClosures is not supported in STON.

The code inside a block can refer to and even affect state outside the block. Furthermore the return operator is quite special as it returns from some outer context.

A subset of BlockClosures are those that are clean. These do not close over other variables, nor do they contain a return. By using their source code representation, it is possible to serialise/materialise them.

You can try this by adding the following methods:

BlockClosure>>#stonOn: stonWriter  self isClean    ifTrue: [ stonWriter writeObject: self listSingleton: self printString ]    ifFalse: [ stonWriter error: 'Only clean blocks can be serialized' ]

BlockClosure>>#stonContainSubObjects  ^ false

BlockClosure class>>#fromSton: stonReader  ^ self compilerClass new      source: stonReader parseListSingleton;      evaluate

With these additions you can do the following:

 STON fromString: (STON toString: [ :x :y | x + y ]).

Note that the actual class name depends on the Pharo version (BlockClosure in Pharo 7, FullBlockClosure in Pharo 9 and maybe soon CleanBlockClosure - Marcus is working on that last one and that would be very cool because it would say exactly what it it).

I am still not 100% convinced to add this as a standard feature to STON. Using source code fully exposes the implementation, while using the compiler can be dangerous. It also adds a dependency on source code and the compiler. But it would be good if people can experiment with this feature.

Does this help you ?

Regards,

Sven

PS: I would not modify an object just to serialise it.

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On 30 Nov 2020, at 18:19, Offray Vladimir Luna Cárdenas <offray.luna@mutabit.com <mailto:offray.luna@mutabit.com>> wrote:

Hi,

I'm using STON for all my light storage serialization needs, like the Grafoscopio notebooks, and I also love it, as Russ stated in their mail question, and I share with him a similar request: for my Brea[1] static site generator I would like to store some BreaQuery objects as external STON files, and recover them, so I can run the queries that recreate/update the website easily. I could store them as Grafoscopio notebooks, but I don't want to make Grafoscopio a prerequisite for Brea or I could use Fuel, but I would like to store queries as a diff friendly text based format. I have considered Metacello/Iceberg packages to export code in a diff friendly format, but It maybe overkill. So I would like to see if STON can serve me here too.

[1] https://mutabit.com/repos.fossil/brea/ <https://mutabit.com/repos.fossil/brea/> [2] https://mutabit.com/repos.fossil/indieweb/ <https://mutabit.com/repos.fossil/indieweb/>

So far, I'm able to serialize a code block as a string using:

BreaQuery>>asStonModified    self codeBlock: self codeBlock asString    ^ STON toStringPretty: self

But I'm unable to populate a block from a string. There is any way to make a string, lets say 'a + b', to become the code contents of a block, ie: [a + b ] ?

Thanks,

Offray

-------------------------------------------- Stéphane Ducasse http://stephane.ducasse.free.fr <http://stephane.ducasse.free.fr/> / http://www.pharo.org <http://www.pharo.org/>  03 59 35 87 52 Assistant: Aurore Dalle  FAX 03 59 57 78 50 TEL 03 59 35 86 16 S. Ducasse - Inria 40, avenue Halley,  Parc Scientifique de la Haute Borne, Bât.A, Park Plaza Villeneuve d'Ascq 59650 France

-------------------------------------------- Stéphane Ducasse http://stephane.ducasse.free.fr <http://stephane.ducasse.free.fr> / http://www.pharo.org <http://www.pharo.org>  03 59 35 87 52 Assistant: Aurore Dalle  FAX 03 59 57 78 50 TEL 03 59 35 86 16 S. Ducasse - Inria 40, avenue Halley,  Parc Scientifique de la Haute Borne, Bât.A, Park Plaza Villeneuve d'Ascq 59650 France